# Chainsaw Dyno bring saws to there knees. Build from start to end with video



## chadihman (May 11, 2013)

Got the dyno done for the most part. I have lots of pictures of the build and a video of a MS 460 begging for mercy.


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## RedneckChainsawRepair (May 11, 2013)

Wheres the video and does it show read outs etc.


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## chadihman (May 11, 2013)

I only ran this 460 so far and didn't do much testing yet. The coolest thing I seen so far is how much the air filter affects the saw. I was running the saw under load and recording my numbers when I thought I'll remove the air filter while its under load and see if it does anything. Wow I pulled the air filter off and the saw gained 400 rpms and the hydraulic pressure raised along with the torgue reading on the scales. I figured it out quick and the saw gained .3 hp with taking the air filter off. I'm so excited and cant wait to put all kinds of mods to the test. I ran a full tank of fuel through the 460 in five min. The hyd oil reached 150 deg in five min so I wont need a cooler. This is probably the most fun I've had desighning and building. Here's the video[video=youtube_share;VGpxVzkYU70]http://youtu.be/VGpxVzkYU70[/video]


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## mt.stalker (May 11, 2013)

Nice brainstorming and fab work . Kudos to ya


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## parrisw (May 11, 2013)

Very cool, did you get a HP reading close to stock?


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## B Harrison (May 11, 2013)

Looks like your adding leverage to the 1' bar the way you have it welded 2.5" off of the center of the axis. (on the square tube) An observation not a factual statement.

My opinion: You theoretically should have the bar tangent to the axis and 12" from the center of that axis for the true ft lbs.
That being said its the first one I have seen and I think your right on for measuring gains of real world saw performance.
Who cares about hp ratings, that thing looks to be as good a gadget as we need.

Its not as much fun as cutting cookies on a clock though.


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## chadihman (May 11, 2013)

parrisw said:


> Very cool, did you get a HP reading close to stock?



This 460 is one that I took the squish band way to far on and was very disapointed in the torque. My brothers 460 and my 461 kill this one so this saw is a bad one for testing. It came out to only 3.83 hp. It was easy to see an increase in power when I removed the air filter so I'm stoked about that. I'll test a stock 461 next to see how close the readings are. Don't worry there will be many more vids to show with numbers later.


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## ozflea (May 11, 2013)

I wouldn't mind making one of those do you have a material list at least you have a guide to seeing if your gaining or not


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## old-cat (May 11, 2013)

SUPER! SUPER! SUPER! I like it!:msp_thumbsup:


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## chadihman (May 11, 2013)

I have to give credit and another thank you to bigwhiteash for making the shaft for the 24 tooth sprocket to ride on. Thank to anyone who gave there ideas. Dynodave helped me with his knowledge from a bike dyno.


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## Rudolf73 (May 11, 2013)

Fantastic job Chad! 

There is a German testing site that has actual dyno numbers on stock saws (don't remember the site off the top of my head) Sawtroll? 

This would help you better corilate your test numbers because the advertised hp numbers on saws are not real accurate as you probably know.


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## chadihman (May 11, 2013)

Rudolf73 said:


> Fantastic job Chad!
> 
> There is a German testing site that has actual dyno numbers on stock saws (don't remember the site off the top of my head) Sawtroll?
> 
> This would help you better corilate your test numbers because the advertised hp numbers on saws are not real accurate as you probably know.



Good to know! Thanks


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## ozflea (May 11, 2013)

The most important thing is to get a base line number then see if theres a gain or lose your dyno would achieve that goal


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## old-cat (May 11, 2013)

May I suggest an experiment/test. How about doing engine mods step by step, one mod then test, then another. Such as muffler mod - test, then port the exhaust only - test, tighten up the squish clearance - test, etc. etc.


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## chadihman (May 11, 2013)

old-cat said:


> May I suggest an experiment/test. How about doing engine mods step by step, one mod then test, then another. Such as muffler mod - test, then port the exhaust only - test, tighten up the squish clearance - test, etc. etc.



That's the plan. I'm going to test my 461 stock and then with a dual port muffler shortly.


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## boxygen (May 11, 2013)

If I understood this Rep thing or if I had any to give. Id give it all to you. I suspect others will step in in that department. opcorn: Nice work.


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## PogoInTheWoods (May 11, 2013)

old-cat said:


> May I suggest an experiment/test. How about doing engine mods step by step, one mod then test, then another. Such as muffler mod - test, then port the exhaust only - test, tighten up the squish clearance - test, etc. etc.



Maybe it's just me, but wouldn't that sorta be the fundamental reason to go to the trouble of designing such a prototype in the first place?


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## locofrog (May 11, 2013)

You sir are a freakin rocket scientist. Excellent work bro...

Loco


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## Stihlman441 (May 11, 2013)

Rep sent
Very usefull tool for saw builders.


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## rocketnorton (May 11, 2013)

pretty cool... the hp numbers wont be as important as the changes in them w/mods, setup, tuning. you'll see the diff of 1/8 turn on mix screws... speakin from bike exp. is a printer 4 power curves next?


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## z71mike (May 11, 2013)

Excellent work man. Much kudos. I want one! How much do you think ya have sunk into it, if ya don't mind me askin? Just to see how unaffordable it would be for me


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## Venomvpr900 (May 11, 2013)

Rep sent. Very nice work. Can't wait to see some tests


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## chadihman (May 11, 2013)

z71mike said:


> Excellent work man. Much kudos. I want one! How much do you think ya have sunk into it, if ya don't mind me askin? Just to see how unaffordable it would be for me



Roughly $750 in supplies. I would have to have $1500 to let this one go. It would be much faster on the next one I build. I don't have the time now to build but come winter ill be into making a couple more to sell.


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## chadihman (May 11, 2013)

The 460 is next for a ported big bore. It will be time consuming but it will get the dyno test after every little mod.


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## LegDeLimber (May 11, 2013)

Congrats!
Glad to see it in real life.

Hmm, ad a bit of creative plumbing to feed the carb from multiple tanks 
for switching feed streams on the fly and run a mix oil tests.
hard to say about the residual lube altering on the fly testing though.

A bar oiler feed would take longer for the chain to clear and probly
not able give a complete oil changover without stopping and washing the chain.

this sort of (a more affordable) rig should open up some interesting things.


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## ozflea (May 11, 2013)

Since i'm no mastermind in hydralics what size pump did you use in your set up and i wonder if power steering pumps out of the heavier cars or lite trucks would be suitable for a test machine ?


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## MechanicMatt (May 11, 2013)

Very Cool! I like the "outside the box" thinking. Not many guys are left in this world that can build anything for themselves. Your Dyno is cool, I bet you had some smile on your face when you saw it working for the first time.


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## chadihman (May 11, 2013)

MechanicMatt said:


> Very Cool! I like the "outside the box" thinking. Not many guys are left in this world that can build anything for themselves. Your Dyno is cool, I bet you had some smile on your face when you saw it working for the first time.



Thanks! Yup still got that smile


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## ozflea (May 11, 2013)

Heres Ricks (sawking) dyno 

https://www.youtube.com/watch?v=7wYx7gKFZrI

https://www.youtube.com/watch?v=AAbvgUJ-_p4


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## chadihman (May 11, 2013)

I designed and built this electric power unit three years ago. It has a 10 hp electric motor running two hyd pumps. One pump supplys 12 gpm to a variable speed controlled hyd high torque motor that is connected to a pto shaft. The other pump supplys oil for a hyd valve for two remotes. Its used many times a day to run farm equipment in a shop for testing. I love to design and build. I have many more things I have built but I wont ramble on about those.


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## chadihman (May 12, 2013)

[video=youtube_share;HfaNjDBPLes]http://youtu.be/HfaNjDBPLes[/video]


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## ozflea (May 12, 2013)

Yes you've done a fine job i'd like to duplicate your dyno for my own use but have no clues on the pump size any help would really be appreciated 

Bob.


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## chadihman (May 12, 2013)

ozflea said:


> Yes you've done a fine job i'd like to duplicate your dyno for my own use but have no clues on the pump size any help would really be appreciated
> 
> Bob.



I used a 4 gpm pump. A 4 or 5 gpm will work. I used a 24 tooth sprocket to keep my pump rpms below 4000 rpms. Cavitation will destroy a pump fast if the rpms are to high.


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## ozflea (May 12, 2013)

chadihman said:


> I used a 4 gpm pump. A 4 or 5 gpm will work. I used a 24 tooth sprocket to keep my pump rpms below 4000 rpms. Cavitation will destroy a pump fast if the rpms are to high.



Thanks ol mate at least now i'll know where to start thank you

Is there a size for the oil tank as a minimium as i said i'm a bit nieve


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## chadihman (May 12, 2013)

ozflea said:


> Thanks ol mate at least now i'll know where to start thank you
> 
> Is there a size for the oil tank as a minimium as i said i'm a bit nieve



Mine is 3 gal. It will handle 5-7 min of heavy load till the oil gets to hot. A universal trany cooler could be used in the return line back to the tank.


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## ozflea (May 12, 2013)

chadihman said:


> Mine is 3 gal. It will handle 5-7 min of heavy load till the oil gets to hot. A universal trany cooler could be used in the return line back to the tank.



Thanks again ol mate i'll make a start in the next week or so then at least i'll know whether i'm improving it or buggering it .... stick to what you been doing you have been a great inspiration ... now go and have a little fun.

Bob.


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## 3000 FPS (May 12, 2013)

That is very impressive. I like the fact that you can pull the air filter off and see a rise in horse power in real time. It does not get any better than that.


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## T0RN4D0 (May 12, 2013)

Shouldn't you retune if you pop of the air filter? I have a feeling that the .3hp ain't just from better air flow. It's also from making the saw run leaner.


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## Moparmyway (May 12, 2013)

Fantastic work !!
Your torque arm on a floating mount is brilliant !!


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## tdi-rick (May 12, 2013)

Rudolf73 said:


> Fantastic job Chad!
> 
> There is a German testing site that has actual dyno numbers on stock saws (don't remember the site off the top of my head) Sawtroll?
> 
> This would help you better corilate your test numbers because the advertised hp numbers on saws are not real accurate as you probably know.



Home


Geprfte Motorsgen

Cool dyno mate, great build.


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## Rudolf73 (May 12, 2013)

tdi-rick said:


> Home
> 
> 
> Geprfte Motorsgen
> ...



Cheers Rick!


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## deezlfan (May 12, 2013)

When I saw the unit in your pictures, the first thing I thought of is: I could modify it to run a wood splitter... Guess i just can't leave anything as intended. Cool build by the way!


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## bplust (May 12, 2013)

Excellent work!


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## chadihman (May 12, 2013)

locofrog said:


> You sir are a freakin rocket scientist. Excellent work bro...
> 
> Loco



No sir I'm not a rocket scientist. Even though some of the homemade bombs my brothers and I made as kids turned into rockets. It really is a miracle that I still have all my fingers. Being a curious farm boy never left me. My little girl calls me tinker as she learned the meaning of a tinker on the movie tinker bell.


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## sachsmo (May 12, 2013)

chadihman said:


> Got the dyno done for the most part. I have lots of pictures of the build and a video of a MS 460 begging for mercy.



That is really kewl,

I have a not so scientific approach, strap a saw onto a Alaskan type mill and start ripping through an 18' 30" Oak.

Not much for bragging rights, but it WILL separate the men from the boyz!


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## parrisw (May 12, 2013)

How did you center the shafts on the box that the pump is in so it would run true?


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## nmurph (May 12, 2013)

T0RN4D0 said:


> Shouldn't you retune if you pop of the air filter? I have a feeling that the .3hp ain't just from better air flow. It's also from making the saw run leaner.



Yep, if you don't add more fuel adding more air makes it leaner.





.

If you can read this, thank a 346


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## 3000 FPS (May 12, 2013)

T0RN4D0 said:


> Shouldn't you retune if you pop of the air filter? I have a feeling that the .3hp ain't just from better air flow. It's also from making the saw run leaner.



I dis-agree. If the saw is sucking more air and has become leaner then if you richen it up with more air, will that not give more fuel air mixture and more horsepower. That is what this dyno will prove, no more speculation.


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## parrisw (May 12, 2013)

3000 FPS said:


> I dis-agree. If the saw is sucking more air and has become leaner then if you richen it up with more air, will that not give more fuel air mixture and more horsepower. That is what this dyno will prove, no more speculation.



If the saw is pulling more air, it will also pull more fuel.


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## PogoInTheWoods (May 12, 2013)

3000 FPS said:


> I dis-agree. If the saw is sucking more air and has become leaner then if you richen it up with more air, will that not give more fuel air mixture and more horsepower.



More air doesn't enrich an already lean air to fuel mixture. And while a saw may suck more fuel (to an extent) due to the removal of the air filter, it may not suck enough to compensate for the additional airflow into the system (depending on the tuning at the time), thereby most likely resulting in a lean condition....same as any additional source of air introduced to the system not compensated for by adjusting the mixture accordingly. And yeah, it may scream under those conditions...until the piston melts down.

Conversely, a completely funky air filter whose lack of airflow has been compensated for by leaner and leaner tuning over time will certainly create a severely lean condition if replaced by a new/clean air filter...and probably burn up the top end if the mix isn't re-enriched enough to compensate for all the "new" air.

Too much air is too much air if not compensated for regardless of the source.

But back to the dyno!!!


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## 3000 FPS (May 12, 2013)

parrisw said:


> If the saw is pulling more air, it will also pull more fuel.



I agree but how much of a gain, and we know there will be one, will no longer be speculated on.


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## Hddnis (May 12, 2013)

Cool build, good to see it working!




Mr. HE


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## RiverRocket (May 12, 2013)

That's really Awesome...You should Patent that thing...:msp_thumbup:


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## 3000 FPS (May 12, 2013)

PogoInTheWoods said:


> More air doesn't enrich an already lean air to fuel mixture. And while a saw may suck more fuel (to an extent) due to the removal of the air filter, it may not suck enough to compensate for the additional airflow into the system (depending on the tuning at the time), thereby most likely resulting in a lean condition....same as any additional source of air introduced to the system not compensated for by adjusting the mixture accordingly. And yeah, it may scream under those conditions...until the piston melts down.
> 
> Conversely, a completely funky air filter whose lack of airflow has been compensated for by leaner and leaner tuning over time will certainly create a severely lean condition if replaced by a new/clean air filter...and probably burn up the top end if the mix isn't re-enriched enough to compensate for all the "new" air.
> 
> ...




Except if you have more air through the venturi of a carb it will pass over the jets and pull more fuel. 

If there is an air leak after the carb it will not pull more fuel from the jets.


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## barneyrb (May 12, 2013)

Couple of questions 1) Are you taking into account the gear reduction on your sprockets? 2) By what I can see some of your fluid heat is coming from the way that exhaust outlet is pointing or so it appears from here


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## chadihman (May 12, 2013)

I know that the saw was not to lean because it had the four strokin still going on with no load. It probably made it a little more lean but not enough to hurt anything as I tend to tune em a little on the fat side now anyway. I'll get a video tommorow of the saw running with the air filtr on and off. 

I was just stunned to see the results in front of me when the air filter was pulled off while the saw was held at 9000 rpms. I found that the highest readings for the 460 were at 9000 rpms. It seemed like the saw was still pulling hard at 8000 rpms but the gain on torque was not great enough to raise the Hp because the rpm went down. The torque will continue to rise as the saw is pulled down harder but torque and rpm make hp not torque alone.


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## chadihman (May 12, 2013)

barneyrb said:


> Couple of questions 1) Are you taking into account the gear reduction on your sprockets? 2) By what I can see some of your fluid heat is coming from the way that exhaust outlet is pointing or so it appears from here



The saw has a 7 tooth sprocket and the driven sprocket is a 24 tooth. The the large sprocket is turned 0.29166 times for every turn of the saw sprocket or crank revolution. I have an rpm sensor on the driven shaft. My torque arm is 18" or 1.5' from the center of the pump shaft to the bolt where the arm dropping to the scales is. I watch the saw rpm with a tach on the saw. I crank the needle valve down to pull the saw to 9000 rpms or so then I record the shaft rpm and the weight on the scales. I multiply the weight on the scales by 1.5 for my longer torque arm then multiply the converted weight by the shaft rpms and divied by 5252 to get the hp. 
The exhaust does not make the oil temp rise much if any. Most dyno runs are 30 seconds or so and the oil barely gets warm. If the saw is run under load for 5-6 min then the oil temp is getting a little high but the saw will run out of gas before the oil gets to hot. The oil should cool enough in between the dyno runs enough for me not to worry about.


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## PogoInTheWoods (May 12, 2013)

3000 FPS said:


> Except if you have more air through the venturi of a carb it will pass over the jets and pull more fuel.



That would depend on the settings of the jets, now wouldn't it? And I didn't realize that's how mix was pumped into the carburetor, but that's another discussion for another thread.

The real issues are the gains relative to the adjustments required to optimize the results of any modifications which are designed to increase performance characteristics, whatever the modifications may be.

Seems like there is now a means by which such can be qualified and quantified given enough testing and repeatable results with this dyno. Once some baseline criteria and further refinement of an actual process are established with this thing, a whole new measurement world opens up.

Too much air is still too much air _if not appropriately compensated for_..., whether it comes from the intake, a too lean "H" setting, a bad crank seal, or a muffler mod.

Not wanting to stir anything up..., Just sayin'.

I'm diggin' the dyno.


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## T0RN4D0 (May 12, 2013)

chadihman said:


> I know that the saw was not to lean because it had the four strokin still going on with no load. *It probably made it a little more lean but not enough to hurt anything as I tend to tune em a little on the fat side now anyway.* I'll get a video tommorow of the saw running with the air filtr on and off.
> 
> I was just stunned to see the results in front of me when the air filter was pulled off while the saw was held at 9000 rpms.




This is exactly what i was trying to point out, and one thing the dyno can't help you with if you test it with a single tuning. Tune it fat once, lean the other time, just right the third you should get different results from the same saw. If you had the saw running fat, pulling off the filter maybe just made the perfect fuel/air mixture. If it wasn't too lean when you removed the filter then you were definitely running her way fat. Have you tried runing it with the filter and tuning it a bit leaner? You would probably get similair (altho probably a bit lesser) results.

Im thinking you should actually use the dyno to find the sweet spot while tuning at WOT for every change you make. Only then the data would be objective which is the purpose of dyno testing in the first place


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## PogoInTheWoods (May 12, 2013)

T0RN4D0 said:


> This is exactly what i was trying to point out, and one thing the dyno can't help you with if you test it with a single tuning. Tune it fat once, lean the other time, just right the third you should get different results from the same saw. If you had the saw running fat, pulling off the filter maybe just made the perfect fuel/air mixture. If it wasn't too lean when you removed the filter then you were definitely running her way fat. Have you tried runing it with the filter and tuning it a bit leaner? You would probably get similair (altho probably a bit lesser) results.
> 
> Im thinking you should actually use the dyno to find the sweet spot while tuning at WOT for every change you make. Only then the data would be objective which is the purpose of dyno testing in the first place



Agreed....more or less.

Until baseline criteria are established for any measurements, they will all just be ballpark numbers. Relative measurements of + or - changes are one thing, absolute measurements of specific performance characteristics on a repeatable basis is another story. With enough work on this thing, either one should be easily attainable under specifically controlled conditions, but each need to be viewed in their respective contexts to provide consistently meaningful results, either relative to specific variables, or absolute based on constant measurement conditions.

The possibilities for this project are pretty awesome to think about. Very, very cool.


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## chadihman (May 12, 2013)

parrisw said:


> How did you center the shafts on the box that the pump is in so it would run true?



Made one not good enough second one is the keeper. The sprocket shaft was made by a member on here that goes by bigwhiteash. A local machine shop helped me make the pivoting box that holds the pump. Lots of measuring and a mill was used. I'll try next time to make the shaft and housing by myself. I was thinking I could start with a 1 1/8" shaft and weld it in as good as possible. Then bolt the pump in and lock the 1 1/8" shaft in my four jaw lathe chuck. Adjust the jaws untill the pump shaft pointing toward the tail stock is nice and true then turn the 1 1/8" shaft down to 1" that should make it perfect. 
It took me a good bit of time to get it all welded so everything is in alignment and square.


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## wigglesworth (May 12, 2013)

Cool build man. 3.8hp seems really, really low for a 460....


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## Moparmyway (May 12, 2013)

chadihman said:


> Made one not good enough second one is the keeper. The sprocket shaft was made by a member on here that goes by bigwhiteash. A local machine shop helped me make the pivoting box that holds the pump. Lots of measuring and a mill was used. I'll try next time to make the shaft and housing by myself. I was thinking I could start with a 1 1/8" shaft and weld it in as good as possible. Then bolt the pump in and lock the 1 1/8" shaft in my four jaw lathe chuck. Adjust the jaws untill the pump shaft pointing toward the tail stock is nice and true then turn the 1 1/8" shaft down to 1" that should make it perfect.
> It took me a good bit of time to get it all welded so everything is in alignment and square.



Maybe next one, you use a single shaft, bolt it up and do all of the welding, then remove and cut the shaft and assemble it in pieces into the assembly.
Its easy to play Monday morning QB ..... your idea is brilliant and I might just try something like this in my downtime after the summer ....... stupid me will just be quiet now. 
AWESOME setup !!


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## chadihman (May 12, 2013)

wigglesworth said:


> Cool build man. 3.8hp seems really, really low for a 460....



Yeah I was not happy with 3.8 HP. I put my stock 461 on and it was right at 4 HP. I'm not sure why readings are so much lower than Stihls specs. Its very simple to see a change in HP with just removing the air filter so I think it will do well for testing mod gains. I just wish I could figure out why I'm reading low. Maybe the saws are tested without a bar and chain. I wish I could find other real world HP specs on saws.


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## Rudolf73 (May 12, 2013)

chadihman said:


> Yeah I was not happy with 3.8 HP. I put my stock 461 on and it was right at 4 HP. I'm not sure why readings are so much lower than Stihls specs. Its very simple to see a change in HP with just removing the air filter so I think it will do well for testing mod gains. I just wish I could figure out why I'm reading low. Maybe the saws are tested without a bar and chain. I wish I could find other real world HP specs on saws.



Have you had a look at this site Geprfte Motorsgen

For the 461 they got 4.4kW or 5.9hp @ 9750rpm and 5.0Nm @ 7500rpm 


I assume the difference in your readings are due to pump inefficiencies, bearing friction, etc. The only sure fire way to measure these losses is to have your setup tested by a hydraulic specialist. They will measure the difference in pressure over the pump and measure flow, etc. And then you can calculate numbers on efficiency. Or you can guesstimate you efficiency by using the above information as a guide.


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## ptjeep (May 12, 2013)




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## ozflea (May 12, 2013)

Just maybe horsepower figures aint as important as everyboby thinks your dyno will show if regardless of the saw performance gains or loses at time of testing and give an indication of gains that can be achieved some mods will prove to be worthless if not detremental to the saws performance, then you can see which way to go stick with it and create your own graph or mod curve i would.

Bob.


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## Hddnis (May 12, 2013)

I would guess that only 80% of the power the saw is making is getting to the scale, maybe even less, the rest being lost to friction in the whole setup.

This in no way negates the value of using it for testing modifications since those measurements are independant of the friction losses. The whole system could be tuned and tested to get actual hp measurements if needed.




Mr. HE


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## parrisw (May 12, 2013)

chadihman said:


> Yeah I was not happy with 3.8 HP. I put my stock 461 on and it was right at 4 HP. I'm not sure why readings are so much lower than Stihls specs. Its very simple to see a change in HP with just removing the air filter so I think it will do well for testing mod gains. I just wish I could figure out why I'm reading low. Maybe the saws are tested without a bar and chain. I wish I could find other real world HP specs on saws.



You can account in at least at a minimum of 15% loss on your setup.


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## PogoInTheWoods (May 12, 2013)

Rudolf73 said:


> Have you had a look at this site Geprfte Motorsgen
> 
> For the 461 they got 4.4kW or 5.9hp @ 9750rpm and 5.0Nm @ 7500rpm
> 
> ...



Great observation and supports the need for a baseline to establish more accurate absolute measurements. Until a calibration method is applied to the system, a simple "correction factor" based upon known saw specs could possibly be introduced into the system efficiency math for more realistic measurement results in the meantime.

Relative +/- modification gains can obviously still be determined since they are, well, relative on a percentage basis.


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## Naked Arborist (May 12, 2013)

Losses here losses there who cares. The numbers can be adjusted if you like to see big HP# readings. This high pressure juice box is the chit. I like it a lot. I think some junk could be used and the price could be knocked down to two three hundred. That's a sweet deal anyway you slice it. 1,500 done or back yard bits for 250 

Nice work!


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## chadihman (May 12, 2013)

Its really hard to believe that I'm loosing 20% but maybe thats it. The bearings on the unit spin free and the chain feels as if it pushes just as easy as when pushed on a real bar. The pump drag should have no effect at all on the the loss because the pump rotates. The extra pump drag should be put to the scales. 
Does anyone know how the saws are tested for hp. With or without a bar and chain. The bar and chain would make a big change. 
Well if its 20% off so be it. I could care less if it has 1 or 100 hp. It looks like so far the air filter removal made a jump in power that was easily picked up. I'm happy that I can get a % in power gain or loss with mods. This dyno is all about before and after.


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## parrisw (May 12, 2013)

chadihman said:


> Its really hard to believe that I'm loosing 20% but maybe thats it. The bearings on the unit spin free and the chain feels as if it pushes just as easy as when pushed on a real bar. The pump drag should have no effect at all on the the loss because the pump rotates. The extra pump drag should be put to the scales.
> Does anyone know how the saws are tested for hp. With or without a bar and chain. The bar and chain would make a big change.
> Well if its 20% off so be it. I could care less if it has 1 or 100 hp. It looks like so far the air filter removal made a jump in power that was easily picked up. I'm happy that I can get a % in power gain or loss with mods. This dyno is all about before and after.



Sounds good, in the end that's all that matters, is in knowing what kind of difference you made. You could just calibrate it to stock HP numbers and call it good.


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## wigglesworth (May 13, 2013)

Put a known HP electric motor on it so you can compare the known to the readout. Should get you alot closer to the correct percentage of loss. 

Just my .02....


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## Big_Wood (May 13, 2013)

repped


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## ttyR2 (May 13, 2013)

Dyno's are only good for relative measurements. That's why quality high perf shops don't like to quote HP/torque figures because the same engine wouldn't read that on a different dyno.


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## young (May 13, 2013)

ttyR2 said:


> Dyno's are only good for relative measurements. That's why quality high perf shops don't like to quote HP/torque figures because the same engine wouldn't read that on a different dyno.



right on, one dnyo jet to the next on cars have different figures. not to mention mustang dyno numbers. 

baseline compared to end result and the percentage gain on the same dyno is all that matters.


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## Yukon Stihl (May 13, 2013)

chadihman said:


> I know that the saw was not to lean because it had the four strokin still going on with no load. It probably made it a little more lean but not enough to hurt anything as I tend to tune em a little on the fat side now anyway. I'll get a video tommorow of the saw running with the air filtr on and off.
> 
> I was just stunned to see the results in front of me when the air filter was pulled off while the saw was held at 9000 rpms. I found that the highest readings for the 460 were at 9000 rpms. It seemed like the saw was still pulling hard at 8000 rpms but the gain on torque was not great enough to raise the Hp because the rpm went down. The torque will continue to rise as the saw is pulled down harder but torque and rpm make hp not torque alone.



Try a quick test and hook up some shop air from the compressor to the carb,like a mock turbo.Set a regulator for a few pounds,and increase i gradually and see what happens.
Thomas


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## mad murdock (May 13, 2013)

Mega cool dyno rep sent. You could come up with some custom K&N filter adapters for different saws, and have booked numbers on %increase in performance. Chads performance customs! Nice work professor!!


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## Justsaws (May 13, 2013)

Well done, well done indeed.


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## watsonr (May 13, 2013)

Yukon Stihl said:


> Try a quick test and hook up some shop air from the compressor to the carb,like a mock turbo.Set a regulator for a few pounds,and increase i gradually and see what happens.
> Thomas



Probably lean the motor out, we know what happens to lean engines. Could we use your saw first?


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## chadihman (May 13, 2013)

watsonr said:


> Probably lean the motor out, we know what happens to lean engines. Could we use your saw first?



Yeah if blowing charged air in the carb won't blow it up I could inject nitro


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## drkptt (May 13, 2013)

Why is the torque arm so long? Scale maxes out?


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## LegDeLimber (May 13, 2013)

a shorter torque bar would reduce (*usable?) sensitivity and make it harder
to "see" small changes in the power output.

* i believe the reasons are somewhere 
in the math of signal to noise & mechanical ratios,
But but pills for my knees are trowing my brain to pain ratios off for now.


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## drkptt (May 13, 2013)

LegDeLimber said:


> a shorter torque bar would reduce (*usable?) sensitivity and make it harder
> to "see" small changes in the power output.
> 
> ...



A shorter torque arm increases resolution and makes it easier to see small changes in torque.


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## half_full (May 13, 2013)

Very cool! can't wait to see more mod results. As stated, who cares about actual HP accuracy when you can measure gains/losses for each mod.


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## PogoInTheWoods (May 13, 2013)

half_full said:


> ....who cares about actual HP accuracy when you can measure gains/losses for each mod.



Uhhh..., compared to what?

I'd be sorta upset too if I built one of these and it told me my MS460 was only puttin' out 3.x HP, but it sure as hell woke up when I removed the air filter. So what? My Mantis does that.

Baselines are required for any of it to have much meaning. 

And I disagree with the statement that HP ratings aren't relevant to the process. That's sorta what dyno's do and how gains and losses are determined, again, given baselines and accurate calibration against known standards.

Otherwise, just grab a stopwatch and go cut some cookies for more "scientific" results.

This has serious possibilities if refined. Just being satisfied with relative averages seems like a wasted effort to me considering how much has already been put into the project. Ya can get the same "relative gain and loss averages" just using a tach if RPM's are all you care about.

But don't get me wrong... I'm not trying to be a dark cloud raining on the parade. Quite the opposite, and would strongly encourage more refinement of an already seriously awesome effort.


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## 7sleeper (May 13, 2013)

I also find this a fantastic project! :msp_thumbsup: I would like to rep all participents but this stupid rep system is kind of restrictive.:msp_thumbdn:

I have a question about the ¨power loss¨. We have often read by sawtroll that echo has horrible hp numbers compared to the others. Then again the myth has it that echo measures hp numbers at the bar tip compared to the others. Do we now see a similar ¨power loss¨?

7


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## lesorubcheek (May 13, 2013)

chadihman, you've done an incredible job! You  You're an inspiration showing what can be done if one wants to accomplish something. Sure all the details will come in time. Key is you now have a foundation to build upon with endless possibilities (data logging / recording, calibration, comparitive analysis, sensitivity refinement....) Door is now wide open for all kinds of things to answer questions with measurment instead of just guessing and speculating. Really wish I had the sense and time to make one. Gets my vote for one of the best saw related threads on AS in all time. Can't wait to see what follows.

Dan


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## LegDeLimber (May 13, 2013)

well crap, I'm thinking about the amount of movement at the end of a long bar
But seems I was still was reversed like using a wrench about the actual work.

Sorry for throwing in inaccurate thoughts and cluttering the thread guys,
Dang pain meds and broken up sleep make things get a bit fuzzy at times.


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## Moparmyway (May 13, 2013)

drkptt said:


> A shorter torque arm increases resolution and makes it easier to see small changes in torque.



I am gunna dis-agree with this ....... a longer arm will give higher numbers, allowing math to be more accurate. The question arises about max scale readings, but if the scale can handle it, a 10 foot bar would show the smallest change in torque, or a 100 foot bar for that matter (Molson XXX talking there) !!


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## Rudolf73 (May 13, 2013)

The way I see it, you are measuring "at the wheel" hp, which means results will always be lower than actual hp numbers. 

IMO it would be good to have some kind of idea on the loses and therefore an estimated engine hp value. You could then run any saw on the dyno and have an idea how close it is to stock numbers, especially if you don't plan on modding it etc.


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## Moparmyway (May 13, 2013)

PogoInTheWoods said:


> Uhhh..., compared to what?
> 
> I'd be sorta upset too if I built one of these and it told me my MS460 was only puttin' out 3.x HP, but it sure as hell woke up when I removed the air filter. So what? My Mantis does that.
> 
> Baselines are required for any of it to have much meaning.




His 460 was ported and admittantly not as good as at least one other stock saw. So his port job didnt produce the numbers he wished for, it aint the first time, and probably wont be the second time someone ported something without stellar results. The whole purpose of removing the AF was to see if the setup would show a difference, and it did !!! Someone should buy Chad a beer !! His baseline should have been at the RPM's that Stihl rated the saw at .......... any other RPM isnt a fair comparison. His invention will show what RPM has the most power ........ thats all we need !! Show me where my saw produces the most power, and I can aim for those RPM's in the cut ........ where is the downside ?? Show me how a MM improves usable torque (no matter if its calibrated or not, an increase is an increase!!)

Baseline for each saw, and then I agree ......... but baseline for "X" saw vs baseline for "Y" saw, whats the difference ??

I said it before and I will say it again ........ AWESOME invention and AWESOME results Chad !!!!


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## Motorsen (May 13, 2013)

Dynos is all about calibration and friction. What you are measuring on your scale is force created by friction in your pump. Next step is to determine losses in setup. Take a stock saw, tune to max performance and call that a benchmark on that given day. X weight on scale equals Y Kw. Then you have to look into airpressure, humidity, temperature to correct your measurements. You made a really great dyno now you have to fine tune it.
This is the best bet on an uncomplicated contruction to measure power I have seen for a very long time. Sharing this with us is priceless.

Regards 

Motorsen


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## drkptt (May 13, 2013)

Moparmyway said:


> I am gunna dis-agree with this ....... a longer arm will give higher numbers, allowing math to be more accurate. The question arises about max scale readings, but if the scale can handle it, a 10 foot bar would show the smallest change in torque, or a 100 foot bar for that matter (Molson XXX talking there) !!



Try again. If the saw is making 1 lb-ft of torque the scale would measure 1 lb if the torque arm is 1 ft long. It would display 0.1 lb if the arm was 10 ft, and 0.01 lb if the arm was 100 feet long.


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## LowVolt (May 13, 2013)

Not smart enough to comment but you did a hell of a job.


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## ozflea (May 13, 2013)

drkptt said:


> Try again. If the saw is making 1 lb-ft of torque the scale would measure 1 lb if the torque arm is 1 ft long. It would display 0.1 lb if the arm was 10 ft, and 0.01 lb if the arm was 100 feet long.



But wouldn't the weight of the 100' arm have to be allowed for ?


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## chadihman (May 13, 2013)

The torque arm was made 18" long because my scales had a limit. 
Every dyno ever built has some drag and had to be calibrated to make accurate. A chainsaw dyno looks bad because its really low torque numbers. This will for sure work for testing small gains or losses. I only used the air filter demonstration to prove a point on how it easily picked up on the gain.


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## Moparmyway (May 13, 2013)

drkptt said:


> Try again. If the saw is making 1 lb-ft of torque the scale would measure 1 lb if the torque arm is 1 ft long. It would display 0.1 lb if the arm was 10 ft, and 0.01 lb if the arm was 100 feet long.


Dude, I dont think you even realize it, but you just prooved my point !!
@ 100 feet, the resolution would be within +/- 0.01
@ 1 foot, the resolution is +/- 01.0

Its WAY more accurate with a longer arm, its just a pain in the rump to move around with a 100 foot arm if his scale can handle the load !!!!!!


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## Karl Robbers (May 13, 2013)

ozflea said:


> But wouldn't the weight of the 100' arm have to be allowed for ?


Sure would, but only in initial set up. IE. everything set up and at rest, press the tare or zero button on your scale and there you have it. Thereafter and reading on the scale is that produced by the saw. 
We could of course in theory place a 100' arm hanging in the opposite direction to counteract the weight and balance the assembly, but then we would definitely need a bigger shed to put our dyno in


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## lesorubcheek (May 13, 2013)

Moparmyway said:


> Dude, I dont think you even realize it, but you just prooved my point !!
> @ 100 feet, the resolution would be within +/- 0.01
> @ 1 foot, the resolution is +/- 01.0
> 
> Its WAY more accurate with a longer arm, its just a pain in the rump to move around with a 100 foot arm if his scale can handle the load !!!!!!



This one has been discussed alot already, and I'm trying to make sure to undertstand it right. Here's the way I wrapped around it (maybe right, maybe wrong, but for right now it seems to make sense) and thought maybe it'd help to throw this out. 

Okay, first, the scale is the measurement tool.... measuring in pounds, plain and simple. Torque is equal to the tangential force (pounds on the scale) multiplied by the lever arm (length of the arm). Next, keep in mind the torque is being produced by the twist from the pump (in turn turned by the saw of course). For simplicity, consider for this little discussion that the torque being produced by the saw and transferred through the pump is constant given the load and RPM.

So, play with what happens with a longer or shorter arm. Start with case of 1 foot arm..... 1 ft-lb torque will cause scale to show a 1 pound measurement... easy to see. Now assume a mod was made to the saw that resulted in a 0.1 ft-lb increase. The scale would be showing 1.1 pounds now, right? This means the scale needs to have an accuracy of 0.1 pounds to accurately show a 0.1 ft-lb increase in torque. If the scale's that accurate, you could see that much improvement and the world is a happy place.

Now figure what happens with a longer arm. Do the extreme case of the 100 ft long arm. Again, twist generated from the pump (originating from the saw of course) is still the same. Use the same torque as before with 1 ft-lb, then the scale will only show 0.01 pounds. Think about that one for a bit..... the scale *would need to be 100 times more accurate* to show the same granularity as the case of the 1 ft arm! The scale isn't changing here, its also constant. That same 0.1 ft-lb increase in the example above is only gonna equate to 0.001 pounds difference on teh scale! This case with the longer arm is gonna be pretty hard to get a scale sensitive enough to even see the change! 

So, figuring I have a scale that ranges say from 0 to 10 pounds or so, is it easier to get a more accurate measurement if I'm weighing a 1 pound weight or a 0.01 pound weight? Odds are I won't even be able to tell the 0.01 pound weight was put on the scale. 

So, maybe it's all screwed up in my head, but seems you'll see more resolution in the number read off a scale with the case of a shorter arm.

Dan


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## Klayton (May 13, 2013)

*who cares if the hp numbers are correct*

i like the idea of comparing one saw to another. lets start hooking some different saws to this thing and get some real life comparison. you know that just like ford does in there trucks stihl can say whatever they want. you know these ratings from factory are sqewed. so lets see what chads ratings are on different saws!!!!


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## Festus (May 13, 2013)

Work=forceXdistance. The thing that is confusing some guys is that the source of energy,in this case, is AT THE FULCRUM(pivot point). Therefore as distance from the fulcrum is increased, torque(rotating force), is decreased. If the force was being applied further away from the fulcrum, the force closer to the fulcrum would be increased, and the distance(how much the lever is moving), would be decreased.

One thought I had (just a theory), is if there were such a thing as a small hydraulic cylinder with exactly 1 sq in surface area, you could just install an accurate pressure gauge and use that for the force reading. It could all be hooked up with clevis' and pins.


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## LegDeLimber (May 13, 2013)

Since I stirred the mud already let me do it again.

I'm trying to think of an example that everyone can relate to.
I've got something in mind but it's an outdoor in the daylight sort of idea.

But try this for now.. look at the guy winding that door spring in this vid
http://www.youtube.com/watch?v=asYaG1-CcN0
(I don't know him, just plucked out a video)
To wind that spring will take the same amount of force
but the reason we use a 20" bar instead of a 6" bar 
is because of the ratio or mechanical advantage.

Just ask yourself this.. 
If your pal was rewinding his door springs and dropped the wrench needed
to tighten the set scew and asked you to keep the spring from turning 
while he retrieved the wrench 
(that probably bounced uphill, under the middle a nearby car)

which bar would be your choice to hold the spring while he chased the wrench? 
I'll bet you'd grab the 20 inch one instead of the 6 incher.


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## Festus (May 13, 2013)

LegDeLimber said:


> Since I stirred the mud already let me do it again.
> 
> I'm trying to think of an example that everyone can relate to.
> I've got something in mind but it's an outdoor in the daylight sort of idea.
> ...



There are two sources of energy here. So it depends which source of energy you are starting with.
In one case the source of energy would be your hand, and the fulcrum would be the other end of the wrench, therefore the longer the wrench, the more force applied on the other end of the wrench. Confusing, because the spring is also a source of energy, but you would be using a wrench, and power from your arm, to work against that energy. In comparison to the machine we are discussing, the door spring would be the base of the lever, or the source of energy, and your hand would be the scale. This makes apparent that the longer the lever on the dyno, the less the scale would read.


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## Arbonaut (May 13, 2013)

wigglesworth said:


> Put a known HP electric motor on it so you can compare the known to the readout. Should get you alot closer to the correct percentage of loss.
> 
> Just my .02....



I like this. You might find a way to use a motor of given size and measure the pressure (in Volts) at various RPM. Seems like it could be more straight forward and easier to dissipate heat. An electric motor might be engaged by a direct shaft bore aligned with the crank. Nice dynamometer BTW.


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## Moparmyway (May 14, 2013)

lesorubcheek said:


> This one has been discussed alot already, and I'm trying to make sure to undertstand it right. Here's the way I wrapped around it (maybe right, maybe wrong, but for right now it seems to make sense) and thought maybe it'd help to throw this out.
> 
> Okay, first, the scale is the measurement tool.... measuring in pounds, plain and simple. Torque is equal to the tangential force (pounds on the scale) multiplied by the lever arm (length of the arm). Next, keep in mind the torque is being produced by the twist from the pump (in turn turned by the saw of course). For simplicity, consider for this little discussion that the torque being produced by the saw and transferred through the pump is constant given the load and RPM.
> 
> ...



Think of it like this:
The pump is gunna twist the arm, no matter what length arm we see, the pump will twist with torque
Now which arm will move further - a 1 foot long arm, or a 10 foot long arm ?
The longer arm will want to move a greater distance - and the scale will show that as more pressure in pounds.
The scale doesnt need to be 100 times more accurate, but it would need to have 100 times the reading range


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## lesorubcheek (May 14, 2013)

Moparmyway said:


> Think of it like this:
> The pump is gunna twist the arm, no matter what length arm we see, the pump will twist with torque
> Now which arm will move further - a 1 foot long arm, or a 10 foot long arm ?
> The longer arm will want to move a greater distance - and the scale will show that as more pressure in pounds.
> The scale doesnt need to be 100 times more accurate, but it would need to have 100 times the reading range



There's a good reason I'm not a teacher :biggrin:. The previous garage door spring is a great example though, it shows very well the situation...

Try to imagine you are holding a tube. You have this round tube and you're holding it with both hands (oh I can see where this could go). On one end of the tube, a straight rod is welded on the tip, 90 degree angle and you're holding it so the welded on rod is pointing straight in front of you. I'm not an artist either, or I'd try to draw this. Let's say the arm is 1 ft long. A kid (your's or a neigborhood kid) has his hand on the end of the rod. Now, you twist downward as hard as you can. The kid try's to prevent you from twisting down by pulling up on the end of the rod. Might be a close call... depends on how muscled up the kid is and how strong you are... 

Now lets make that rod 100 ft. Go ahead and twist as hard as you can. I'll bet you that kid will be yawning and saying "I'm waiting, anytime you're ready". Making the rod longer is giving the kid the advantage, right? You're still applying the same torque. Just like with the garage door spring example.... longer lever gives the advantage to the guy holding the rod, not to the spring. 

So, in the example, you're the pump applying a twist. The kid is the scale. The scale is going to show alot less weight as the arm gets longer, just like the kid has to apply less lift to counter your twisting. Showing less weight equates to less total measurement granularity. The more desirable measurement would be so you're using a wider range of the scales measuring range. For instance, if its a 0 to 25 pound scale being used, you want to measure things in the 10 to 20 pound range... it'll be more accurate that way. 

Dan


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## drkptt (May 14, 2013)

Moparmyway said:


> ...
> The longer arm will want to move a greater distance - and the scale will show that as more pressure in pounds.
> ....



There's the problem--in my world scales measure force, not distance.


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## Moparmyway (May 14, 2013)

lesorubcheek said:


> There's a good reason I'm not a teacher :biggrin:. Dan




Maybe you should be .........
Lightbulb is now lit
Longer arm equates to less torque at the end of that arm, more distance, but less torque
Appreciate your patience and your example !!


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## chadihman (May 14, 2013)

Sorry I didn't get a video of the #'s yet. My tach sensor on the shaft isn't working. I ordered a new one and it will be a few days. I will have a video with a stock 461 then with a dual port muffler. I can't wait to see what gain a mm will do.


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## Rudolf73 (May 14, 2013)

chadihman said:


> Sorry I didn't get a video of the #'s yet. My tach sensor on the shaft isn't working. I ordered a new one and it will be a few days. I will have a video with a stock 461 then with a dual port muffler. I can't wait to see what gain a mm will do.



What kind of tach are you using on the shaft - laser?


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## spacemule (May 14, 2013)

Moparmyway said:


> Think of it like this:
> The pump is gunna twist the arm, no matter what length arm we see, the pump will twist with torque
> Now which arm will move further - a 1 foot long arm, or a 10 foot long arm ?
> The longer arm will want to move a greater distance - and the scale will show that as more pressure in pounds.
> The scale doesnt need to be 100 times more accurate, but it would need to have 100 times the reading range



You've got it backwards. I'll prove it with examples. The maximum rotational force the chainsaw applies will be a set number. For the sake of simplicity, let's call it 100 pounds. What is 100 foot pounds of torque? 100 foot pounds means that a 1 foot long lever will have 100 pounds of pressure applied at its end, or 100 pounds x 1 foot. A 10 foot long lever will have 10 pounds of pressure applied at it's end, or 10 pounds times 10 feet. In other words, a 10 foot bar with 10 pounds of pressure applied is the same rotational force as a 1 foot bar with 100 pounds of pressure applied. So, a 1 foot bar will have a pressure range from 0 to 100, but a 10 foot bar will have a pressure range from 0 to 10. Hence, the longer bar will require a much more accurate scale because the range of pressure is smaller.


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## chadihman (May 14, 2013)

Rudolf73 said:


> What kind of tach are you using on the shaft - laser?



It's a cheap inductive type with a sensor that picks up rotation of a magnet on the shaft. I found it on eBay. Andy tach. I wouldn't mind spending a little more for a better one. I don't want a hand held. I'd be open for suggestions


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## chadihman (May 14, 2013)

I really wouldn't mind setting this all up with a load cell and a tach attached to a laptop. Electronics get pricey though.


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## spacemule (May 14, 2013)

Moparmyway said:


> Dude, I dont think you even realize it, but you just prooved my point !!
> @ 100 feet, the resolution would be within +/- 0.01
> @ 1 foot, the resolution is +/- 01.0
> 
> Its WAY more accurate with a longer arm, its just a pain in the rump to move around with a 100 foot arm if his scale can handle the load !!!!!!



Not true. Again, you're getting it backwards. .01 pounds of force on a 100 foot bar is equal to 1 pound of force on a 1 foot bar. In other words, a 1 pound difference in force for a 1 foot bar is equal to .01 pounds of force in a 100 foot bar. Pick up 1 pound in your hand and then .01 pounds in your hand. Which is easier to feel? Which will register more accurately on your average scale?


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## Rudolf73 (May 14, 2013)

chadihman said:


> I really wouldn't mind setting this all up with a load cell and a tach attached to a laptop. Electronics get pricey though.



Yes that would be the ultimate setup. The load cells and tach aren't to bad but the software and data logger would push several hundred each. How good is your program writing? lol


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## Hedgerow (May 14, 2013)

Hat's off to you chadihman...
Big rep bomb sent your way...
Now...
Less egg head talk, and more vids...

Oh, and air filter off = more horsepower... Not necessarily from being too lean, just from easier flow. A two stroke motor is just a pump... Take the screen of and let it suck!!!

On to the 461!!!!!!


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## Moparmyway (May 15, 2013)

spacemule said:


> You've got it backwards. I'll prove it with examples. The maximum rotational force the chainsaw applies will be a set number. For the sake of simplicity, let's call it 100 pounds. What is 100 foot pounds of torque? 100 foot pounds means that a 1 foot long lever will have 100 pounds of pressure applied at its end, or 100 pounds x 1 foot. A 10 foot long lever will have 10 pounds of pressure applied at it's end, or 10 pounds times 10 feet. In other words, a 10 foot bar with 10 pounds of pressure applied is the same rotational force as a 1 foot bar with 100 pounds of pressure applied. So, a 1 foot bar will have a pressure range from 0 to 100, but a 10 foot bar will have a pressure range from 0 to 10. Hence, the longer bar will require a much more accurate scale because the range of pressure is smaller.





spacemule said:


> Not true. Again, you're getting it backwards. .01 pounds of force on a 100 foot bar is equal to 1 pound of force on a 1 foot bar. In other words, a 1 pound difference in force for a 1 foot bar is equal to .01 pounds of force in a 100 foot bar. Pick up 1 pound in your hand and then .01 pounds in your hand. Which is easier to feel? Which will register more accurately on your average scale?



See post # 110 ........... there was a loup "POP" when my head was pulled from my arse, and everything was clearer after the Molson XXX wore off. Nice examples !


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## bikesandcars (May 15, 2013)

Great job putting talk into reality, then publishing your reality for others! 

That's 2 steps more than most take and 1 more than many people do once they put the work in. I think it looks great

I read through this entire post and I can't find the answer to a simple question I had.. where on earth do you get a 24 tooth chainsaw sprocket? What did you use for chain? (grind the cutters off?)


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## spacemule (May 15, 2013)

Moparmyway said:


> See post # 110 ........... there was a loup "POP" when my head was pulled from my arse, and everything was clearer after the Molson XXX wore off. Nice examples !



lol. I missed that.


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## Team FAST (May 15, 2013)

*Interesting*

A couple of things:

1. Congrats on the build and the effort. It is really cool! 

I think its important for folks to realize that the horsepower numbers being reported from this are fairly meaningless, within the context of "that saw should be producing XX.X hp" This in no way is meant to disparage this most excellent device you made!

Your horsepower numbers are derived - calculated from a scale reading, a lever arm length, and an observed RPM value. The rotational assemly of the dyno is being driven indirectly from the MUT (motor under test) by a chain drive system. There are bearings on the shaft. Many factors lie between that little combustion chamber (the seed of the POWER) and the readout on your scale.

So you inherently (as all dynos do) have lots of error sources:

- scale inaccuracies (probably as much as 5%)
- torque arm length uncertainty (knowing *exactly* how long it is)
- rpm measurement uncertainty (the meter will have some error associated with it)
- frictional losses in shaft bearings (probably small)
- losses due to chaindrive system (high) <----interesting test.....try just messing with lube oils on your chain drive system as you are running the dyno and watch the toruqe readings change

Note that the hydraulics side as you implemented it is simply for load absorption. The pump efficiencies, performance, etc, have zero bearing on errors associated with the torque reading, only on the absolute capacity of the dyno, and the relationship between the load absorbtion input (your flow valve) and the torque reading. This would only become significant if you chose to automate your dyno with automatic load controls (like a modern Superflow setup). In order words the absorption side has nothing to do with accuracy of torque readings, as long as its stable.

That's just the mechanical parts. The other thing you have to be really aware of....even when trying to do relative measurements, are things like ambient conditions (air temp, humidity, density altitude, etc) as well as the temperature of the saw engine. On a two stroke engine, crankcase temperature has a HUGE impact on engine volumetric efficiency, and effective air fuel ratio....therefore horspower...

All of these factors have to be taken into account when reporting SAE Corrected horsepower numbers. SAE has test procedures and methodlogies to specifically address dyno testing. Not relevant for what you are doing here, of course.

Just some things to think about!

I'm slowly working on my own dyno....eddy current based system using an automotive alternator as the load control and a bank of resistors for load absorbtion.


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## PogoInTheWoods (May 15, 2013)

Excellent!!!


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## chadihman (May 15, 2013)

bikesandcars said:


> Great job putting talk into reality, then publishing your reality for others!
> 
> That's 2 steps more than most take and 1 more than many people do once they put the work in. I think it looks great
> 
> I read through this entire post and I can't find the answer to a simple question I had.. where on earth do you get a 24 tooth chainsaw sprocket? What did you use for chain? (grind the cutters off?)


I found the 24 tooth sprocket in a company from Washington state. I found a cutterless chain online


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## barneyrb (May 15, 2013)

chadihman said:


> I found the *24 tooth sprocket *in a company from Washington state. I found a cutterless chain online



Wonder if my wild thing would pull that....hhhmmmmmmmm


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## Scooterbum (May 15, 2013)

Ignoring all the naysayers, nitpickers and brainiacks. I love it when someone starts out to make something from scratch and finishes it and it works exactly as it's intended purpose. To measure gains and losses when modding a chainsaw.

You should maybe look into manufacturing it. Small niche market, but it's there.Could be differrent versions. Chainsaws aren't the only 2-smokes being modded.

Great work !!!


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## chadihman (May 15, 2013)

Here is the company I got the 24 tooth sprocket from Sprocket Applications


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## ozflea (May 15, 2013)

chadihman said:


> Here is the company I got the 24 tooth sprocket from Sprocket Applications



Thanks ol mate i'll go chase one up .............


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## chadihman (May 16, 2013)

This is the cutterless chain Bailey's - Oregon 72W Cutterless Chainsaw Chain


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## peacmar (May 17, 2013)

One thing I haven't noticed mentioned that would account for the inaccuracy of the reading, friction and inertia aside, is the increase in temperature of the hydraulic fluid. I've built a few small engine dyno in the past and the simplest is driving a positive displacement pump. Hydraulic pumps are simple and cheap to come by and can stop a very large load. I used have a 400 HP rig that used a 50 HP hydraulic pump out of an old combine. There was only one source of measurement in power and that was a pressure/temp gauge. As the pressure went up rolling resistance was placed on the engine and by calculating the temperature increase of the fluid at a given rpm one could determine work done and torque applied. I cannot for the life of me find the old files I had with the formulas in a spread sheet but know I found them online very easily.

So if you take the fluid temp increase, along with the friction of the chain, slippage in the clutch, resistance of a viscous fluid through the pump, and bearing friction all into account. You should have a very accurate setup. As someone who has spent the last ten years developing import race engines and countless hours of dyno work I must say nice work!


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## chadihman (May 17, 2013)

Not sure if I can ask this but here goes. Would anybody be interested in a dyno if the cost was $1500. Maybe I could make them cheaper on the next build. I'm just trying to figure out if this would be worth manufacturing.


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## 67L36Driver (May 17, 2013)

Excellent grass roots approach on your dyno build. Simple and made with readily available parts. Good job.



Only thing I can offer is to keep an eye on the length of run under full load. No telling what duty cycle (on/off) chainsaws are designed for. Fellas running mills could maybe give us a clue.

Watch out for powerhead melt down.

Carl.


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## Gologit (May 17, 2013)

chadihman said:


> Not sure if I can ask this but here goes. Would anybody be interested in a dyno if the cost was $1500. Maybe I could make them cheaper on the next build. I'm just trying to figure out if this would be worth manufacturing.



You're still in the development stage and you're not actually advertising anything for sale so we'll let you run with this a little. Call it market research or something.

If you start building them and you're advertising and selling them on AS you'll need to get a sponsorship.

Good job, by the way. And good luck.


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## booger1286 (May 18, 2013)

Awesome build! Somebody might have already said this but, looks like it could use another pivot point right above the base on the scales. Especially since the arm is off center.
That should make a difference in your readings for the better.


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## nelson727 (May 18, 2013)

First saw this dyno thread a few days ago. Man my hat is off to you chadihman that is some beautiful work. I just keep my saws running for the job so wouldn’t pay $1500 for a dyno. If I lived next door to you I’m sure I would be asking you to build this and that for me and soon be up to 15K. Amazing!


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## peacmar (May 18, 2013)

I've been thinking about this thing since I first read it and have an idea for a way to verify the readings.

Use an electric motor you have laying around, any motor of any size, and use a volt meter and amp meter to record the wattage used when loading the motor to its full potential. Wattage can be easily converted to HP with a simple calculation. Compare your wattage input to your dynos recorded power absorbtion and you will then know your correction factor. Try this when your fluid is cold and hot and you may be able to interpolate and graph a correction chart based in fluid temperature. I would think it would be a linear function. Then forget the rest and keep it simple. As most who have worked with a dyno know, it is about proving repeatable results and recording changes, not the final numbers. So if you start out with a baseline reading of a saw then record power improvements after each mod and can repeat the results you would therefore have a scientifically proven method of data acquisition.


An individual could also use a spare saw as a "mule engine" one that is never touch or changed. A mule engine is used to make the first couple of runs each time a dyni is used. Those runs are compared to the previous mule engine runs, and a correction factor is derived from the difference in results. Allowing an individual to compensate for changes in testing conditions that may have occurred over a couple weeks or months between tests.


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## chadihman (May 19, 2013)

peacmar said:


> I've been thinking about this thing since I first read it and have an idea for a way to verify the readings.
> 
> Use an electric motor you have laying around, any motor of any size, and use a volt meter and amp meter to record the wattage used when loading the motor to its full potential. Wattage can be easily converted to HP with a simple calculation. Compare your wattage input to your dynos recorded power absorbtion and you will then know your correction factor. Try this when your fluid is cold and hot and you may be able to interpolate and graph a correction chart based in fluid temperature. I would think it would be a linear function. Then forget the rest and keep it simple. As most who have worked with a dyno know, it is about proving repeatable results and recording changes, not the final numbers. So if you start out with a baseline reading of a saw then record power improvements after each mod and can repeat the results you would therefore have a scientifically proven method of data acquisition.
> 
> ...


Well I'm now working on getting it dialed in. I got some vibration dampening pads for the scales to sit on and a new scales on the way to compare the two. I'm reworking the hoses for less drag. I'm using my stock 461 as the mule.


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## LegDeLimber (May 19, 2013)

My gut take on this is...
It'll be a darn handy thing to have in the shop for all the reasons mentioned
around tuning motors and keeping notes on 'em.
hmmm, how many adapters can you rig for checking the [local ?] lawn mower racer's engines etc ??

2nd: I'd wager this thing will be a big hit at the first few GTG's 
*IF* you have the opportunity/time etc to carry it around...

I'd love to make my first trip to a GTG and see the first "dyno races"
...could make for some interesting "tuning clinics" and so on.

Ahh I have other ideas, 
but as always more ideas will lead to more new variables to have differing opinions on.


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## chadihman (May 19, 2013)

LegDeLimber said:


> My gut take on this is...
> It'll be a darn handy thing to have in the shop for all the reasons mentioned
> around tuning motors and keeping notes on 'em.
> hmmm, how many adapters can you rig for checking the [local ?] lawn mower racer's engines etc ??
> ...


I'd haul this to a gtg if one were close by. I would let anyone run and tune there saws on it.


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## LegDeLimber (May 19, 2013)

Chadiham, PM in your box if I didn't goof up sending it.
sorta bouncing from one task to others in prep for knee repairs


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## drkptt (May 19, 2013)

peacmar said:


> One thing I haven't noticed mentioned that would account for the inaccuracy of the reading, friction and inertia aside, is the increase in temperature of the hydraulic fluid. I've built a few small engine dyno in the past and the simplest is driving a positive displacement pump. Hydraulic pumps are simple and cheap to come by and can stop a very large load. I used have a 400 HP rig that used a 50 HP hydraulic pump out of an old combine. There was only one source of measurement in power and that was a pressure/temp gauge. As the pressure went up rolling resistance was placed on the engine and by calculating the temperature increase of the fluid at a given rpm one could determine work done and torque applied. I cannot for the life of me find the old files I had with the formulas in a spread sheet but know I found them online very easily.
> 
> So if you take the fluid temp increase, along with the friction of the chain, slippage in the clutch, resistance of a viscous fluid through the pump, and bearing friction all into account. You should have a very accurate setup. As someone who has spent the last ten years developing import race engines and countless hours of dyno work I must say nice work!



You must have missed the torque arm and scale on this dyno. Change in fluid temperature won't affect the accuracy of the measurement. It will cause difficulty in load control because the viscosity will change and the pressure drop across the regulating valve will drop as the oil heats. This will require adjustment of the valve to maintain constant speed.

I can't imagine using temperature change to calculate dyno load. Pressure and flowrate would do it more accurately.


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## peacmar (May 19, 2013)

drkptt said:


> You must have missed the torque arm and scale on this dyno. Change in fluid temperature won't affect the accuracy of the measurement. It will cause difficulty in load control because the viscosity will change and the pressure drop across the regulating valve will drop as the oil heats. This will require adjustment of the valve to maintain constant speed.
> 
> I can't imagine using temperature change to calculate dyno load. Pressure and flowrate would do it more accurately.




The temperature rise can be calculated as

dt = Ps (1 - μ) / cp q ρ (1)

where

dt = temperature rise in the pump (oC)

q = volume flow through the pump (m3/s)

Ps = brake power (kW)

cp = specific heat capacity of the fluid (kJ/kgoC)

μ = pump efficiency

ρ = fluid density (kg/m3)


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## Hddnis (May 19, 2013)

peacmar said:


> The temperature rise can be calculated as
> 
> dt = Ps (1 - μ) / cp q ρ (1)
> 
> ...





That is not how this dyno is designed to work and such a calculation is less than useless for this setup.



Mr. HE


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## drkptt (May 19, 2013)

That would be a silly way to calculate power for any dynamometer. Note the (1 - μ) term. Your dt is only due to pump inefficiency, not the amount of work put into the system from the engine. The higher the pump efficiency the smaller the temperature rise would be--if the pump was 100% efficient the dt would be zero. How would you go about determining the pump efficiency to use this method?

You do know the big temperature rise occurs across the valve when the pressure drops back to atmospheric, right?



peacmar said:


> The temperature rise can be calculated as
> 
> dt = Ps (1 - μ) / cp q ρ (1)
> 
> ...


----------



## Hddnis (May 19, 2013)

drkptt said:


> ...You do know the big temperature rise occurs across the valve when the pressure drops back to atmospheric, right?




The temp rise would only be from friction and not from the pressure drop.




Mr. HE


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## Naked Arborist (May 19, 2013)

Hedgerow said:


> Hat's off to you chadihman...
> Big rep bomb sent your way...
> Now...
> Less egg head talk, and more vids...
> ...



I thought we'd all be egg heads after reading all this fine technical information. On with the testing please.


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## peacmar (May 19, 2013)

OK before this gets out of hand I only posted the formula for information sake and I understand that this is a steady state resistance load type of dyno. The formula I posted is the basis of some of the oldest small engine dyno there have been. Basically a purposely inefficient hydraulic system that measures power by calculating the inefficiency. Direct drive, minimal loss, most accurate from an empirical stand point. Simply a matter of conversation and things for the OP to ponder in his creation as it grows.


Having worked with hydraulics I do still see one flaw that could hinder performance on large saws of high output. If the fluid heats quickly enough or one would want to do some heavy duty testing of a large displacement saw it could become hard to control such said saw once the fluid does heat up. As the fluid heats and viscosity decreases, so does the torque transmittance to the load cell through the torque arm. The pump may not be able to handle enough pressure to create enough resistance to take a reading.

An example with completely made up and meaningless numbers and values:

An imaginary saw can generate 30 lb/ft of torque at maximum power

A pump will transmit rotational torque to the body that is equal to the force applied on the shaft

Said pump requires 30 lb/ft torque to generate 2000 psi pressure if the fluid is at 80 degrees, pump will absorb power of the saw.

Fluid is now at 150 degrees, pump is able to generate 2000 psi with only 7 lb/ft torque. Doubling the pressure to 4000 psi will only require 20 lb/ft of torque. Pump maxed out and cannot hold back saw until fluid has cooled again.


Again these numbers are made up but the real life specifics are available from the pump manufactures and are something to consider for anybody planning to build one.


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## ozflea (May 20, 2013)

Keep going fellas this puppy will be worth a mint ............. be satisified .............. its not the space shuttle you know


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## Mastermind (May 20, 2013)

chadihman said:


> Not sure if I can ask this but here goes. Would anybody be interested in a dyno if the cost was $1500. Maybe I could make them cheaper on the next build. I'm just trying to figure out if this would be worth manufacturing.



I'm interested.......work out the bugs and it's a deal. :msp_thumbsup:


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## chadihman (May 20, 2013)

Mastermind said:


> I'm interested.......work out the bugs and it's a deal. :msp_thumbsup:



Holy crap I thought you were never leaving that boat. Welcome back! The bugs are getting worked out. My first problem was the drive pins in my 24 tooth sprocket were sliding out. I fixed that with a spot weld on every pin. Second problem was my shaft rpm sensor was not working. Got that working now. Now I'm wating on some vibration dampening pads for the scales to sit on. The vibration made the scales jump a bit. The pile of rags on the video helped a lot. I think I'm going to put a oil cooler on it because the oil got to max temp after I broke in a 460 for one tank of fuel. Wow the 460 bb drinks fuel when its under constant load. This thing sure is sweet for breaking in a saw.


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## tony56 (Jun 4, 2016)

chadihman said:


> Got the dyno done for the most part. I have lots of pictures of the build and a video of a MS 460 begging for mercy.


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## tony56 (Jun 4, 2016)

Would sure like to know where you got the driven sprocket... Is it 3/8", or .325 ?


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## Paragon Builder (Jun 10, 2016)

tony56 said:


> Would sure like to know where you got the driven sprocket... Is it 3/8", or .325 ?


I don't think chad has been around for quite some time. http://www.danzcoinc.com/html/chain_saw_sprockets.html
Has some, or can make them. I'm sure there are others...


Sent from my iPhone using Tapatalk


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## Firemoore98 (Jun 10, 2016)

Buying cool is one thing, making something cool is what impresses me the most. Solid work!!! Thanks for sharing

Jason


Sent from my iPhone using Tapatalk


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## rd35 (Jun 10, 2016)

Wow, I just found this thread. Been working up a design for a dyno (in my head mostly) and the OP dyno is EXACTLY what I was planning to build in terms of the concept. Hydraulic pump to absorb the power. Shaft sensor tach and a scale to read the floating pump torsion created against a lever arm pushing on a digital scale. This is, in my opinion the most simple, yet fully functional and accurate method available to determine power from a chainsaw. Only error is the loss in the pillowblock bearings. I was hoping to be able to measure torsion on the entire assembly to get a more accurate torque reading. HOWEVER, I have not lifted a finger yet. I have been all talk-no go! Awesome job Chad! You actually did it! That thing is just too cool!!!


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## sweepleader (Jun 10, 2016)

VERY NICE, excellent! Maybe in future models you might want to mount the pump sprocket outboard so it could be serviced easily and without messing with the pump shaft or bearings. It would be overhung but with the loads involved that would not seem to be a problem. The bearings themselves could be a source of friction losses, oil lubed bearings would have less drag than greased bearings. Shielded bearings have reduced drag compared to sealed bearings too. You might also want to reduce the chain contact with the bar to a minimum needed to guide the chain between the sprockets.

Maybe you have thought of these things already, in that case, never mind.

Love it, thanks for building it and sharing with all of us. Beautiful.


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## tomdcoker (Jun 11, 2016)

A hydraulic motor is very inefficient and thatis basically what you have. I learned this while running a 5 HP 220 3 phase motor to pull a hydraulic pump on a surface grinder with a phase converter. After 30 minutes the motor was smoking, but a 50 an 20 microfarad running capacitor connected in parallel stopped that. Tom


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## 67L36Driver (Jun 12, 2016)

The pump don't have to be efficient. Just provides the variable resistance so you can measure torque and speed.


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## BrettS (Feb 26, 2017)

*Chainsaw Dyno, bring saws to *THEIR* knees.*


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## sweepleader (Feb 27, 2017)

Just noticed the plate on the scale should have a pivot joint, to prevent binding when the arm from the hydraulic motor rotates. It will not be much but it could throw off the readings quite a bit. The arm will tend to tip the plate with a solid joint causing uneven loading.

This thing is GREAT! Have you run it?


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## chadihman (Feb 27, 2017)

sweepleader said:


> Just noticed the plate on the scale should have a pivot joint, to prevent binding when the arm from the hydraulic motor rotates. It will not be much but it could throw off the readings quite a bit. The arm will tend to tip the plate with a solid joint causing uneven loading.
> 
> This thing is GREAT! Have you run it?


Yes It does have a pivot point so the plate always sits level on the scale. It has a bolt that has two nuts jammed together keeping the bolt from clamping it.


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## chadihman (Feb 27, 2017)

I'd be interested in letting this dyno go.


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## blsnelling (Feb 27, 2017)

You're alive! Hello Chad.


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## anymanusa (Feb 27, 2017)

Soo are there any other dyno results besides the 1?


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## chadihman (Feb 27, 2017)

anymanusa said:


> Soo are there any other dyno results besides the 1?


Ohhh yes theres a bunch of free dyno results and graphs on here somewhere.


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## blsnelling (Feb 27, 2017)

anymanusa said:


> Soo are there any other dyno results besides the 1?


http://www.arboristsite.com/community/search/13307420/


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## grizz55chev (Feb 27, 2017)

blsnelling said:


> http://www.arboristsite.com/community/search/13307420/


This comes up as not available.


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## anymanusa (Feb 27, 2017)

blsnelling said:


> http://www.arboristsite.com/community/search/13307420/


Why does that pull up an error?


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## blsnelling (Feb 27, 2017)

It should pull up all of Chad's threads. Go to his Profile and then Postings. Go to the bottom of that page.


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## chadihman (Mar 12, 2017)

blsnelling said:


> You're alive! Hello Chad.


Hi Brad


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## pioneerguy600 (Mar 13, 2017)

I remember seeing a graph in this older thread, one of Brads saws IIRC,

http://www.arboristsite.com/community/threads/snellerized-ms461-on-the-dyno.272016/


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## Guru LLC (Mar 13, 2017)

I'm still alive too. 

Sorta...


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## pioneerguy600 (Mar 13, 2017)

Guru LLC said:


> I'm still alive too.
> 
> Sorta...


 Did you have any saws run up on the dyno? Can`t remember all the posts in muh small lil brain, just had that one bookmarked from years back.


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## Guru LLC (Mar 14, 2017)

http://www.arboristsite.com/communi...-stock-261cm-gotta-see-this-one.259228/page-5


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## pioneerguy600 (Mar 14, 2017)

Guru LLC said:


> http://www.arboristsite.com/communi...-stock-261cm-gotta-see-this-one.259228/page-5


 Thanks R.


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## Guru LLC (Mar 14, 2017)

Sure don't see many familiar folks here these days Jerry. Everything changes I reckon.


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## pioneerguy600 (Mar 15, 2017)

Lose some and gain some, very few of the members still here from when I joined up ten years ago.


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## Guru LLC (Mar 15, 2017)

I first joined in 2009. I thought this was the greatest forum on the web.


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## fwgsaw (Mar 16, 2017)

Guru LLC said:


> I first joined in 2009. I thought this was the greatest forum on the web.


It still has it moments. Still plenty of good people on here just a lot more PM's going on then threads sometimes. But lots have left some have passed and so goes life. For me I will stay here and look forward to watching the good and the bad come and go.


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## Walter Glover (Apr 4, 2018)

So whatever became of Chad?
Anyone pick up where he left off?


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## chadihman (Apr 4, 2018)

Hey guys. I don't get on here so much anymore. Still running saws and modding one every now and then. The dyno has not been touched for probably two years. I'd love for someone that had the spark I had to take over my dyno. I'd sell it cheap. Make me an offer.


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## Mac&Homelite (Apr 4, 2018)

chadihman said:


> Hey guys. I don't get on here so much anymore. Still running saws and modding one every now and then. The dyno has not been touched for probably two years. I'd love for someone that had the spark I had to take over my dyno. I'd sell it cheap. Make me an offer.


I just came across the thread, but am curious on the saw dyno. Always sorta wanted to get my hands on one since I live in town and dealing with cookies and saw chips gets annoying for testing my builds. Got any pics or link of it by chance?


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## Walter Glover (Apr 4, 2018)

Good to hear from you Chad
I am collecting parts to build a dyno. As I an in Canada purchasing yours is out of the question lol
Will try a disk brake first
Load cell will be a hydraulic cylinder with a dampener and gauge


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## chadihman (Apr 4, 2018)

Mac&Homelite said:


> I just came across the thread, but am curious on the saw dyno. Always sorta wanted to get my hands on one since I live in town and dealing with cookies and saw chips gets annoying for testing my builds. Got any pics or link of it by chance?[/QU





Mac&Homelite said:


> I just came across the thread, but am curious on the saw dyno. Always sorta wanted to get my hands on one since I live in town and dealing with cookies and saw chips gets annoying for testing my builds. Got any pics or link of it by chance?


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## Mac&Homelite (Apr 4, 2018)

Very nice! I would love to have something like that at some point to put a consistent load on a saw for tuning, but I would never use it enough to justify the space for it at the present time.


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## Walter Glover (Apr 6, 2018)

Made the load cell. Gauge will read 100psi with 20 pounds force so will be 10 ftlbs on a 6" lever.


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## chadihman (Apr 7, 2018)

Walter Glover said:


> Made the load cell. Gauge will read 100psi with 20 pounds force so will be 10 ftlbs on a 6" lever.


Don't forget that two stroke saws do not make much torque. You need to measure ft-lbs in at least the .01 lb to be able to see the tiniest increase in HP. My scales measured .001 lb.


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## Walter Glover (Apr 7, 2018)

Thanks Chad. This setup 1 psi is 0.1ftlb so will be worth trying. I do have an electronic scale as well so might do both.


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## chadihman (Apr 7, 2018)

I mod more than saws. This is my Kubota. Added a turbo and boosted the HP 76% Wait till the end of the video as I have some pictures of my fabrication work to fit the turbo under the hood. I'm looking into building a pulling tractor. If only I could get a turbo on a saw.


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## chadihman (Apr 8, 2018)




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## chadihman (Apr 8, 2018)




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## Walter Glover (Apr 8, 2018)

Awesome Chad!!
Beautiful work there


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## chadihman (Apr 8, 2018)

Oh and I mod bird feeders as well.


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## Walter Glover (Apr 9, 2018)

It appears that friction/stiction is the enemy of my hydraulic load sensor
It is repeatable but it takes extra force to overcome the oring stiction. Will try a different seal to see if that can be corrected


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## Walter Glover (Apr 11, 2018)

Stopped by local metal shop. He will plasma cut the parts for the sprocket so no pins! Price not bad either


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## chadihman (Apr 11, 2018)

Walter Glover said:


> Stopped by local metal shop. He will plasma cut the parts for the sprocket so no pins! Price not bad either


Make sure to take pictures along the way.


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## Walter Glover (Apr 11, 2018)

Absolutely
The internal sprocket will be 1/16" thick
Sandwiched berween two 1/4" thick rims.


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## Walter Glover (Apr 12, 2018)

Ordered a strain gauge and amplifier to mess with as well. Should get enhanced accuracy wrt force measurement that way. Will need to figure out a calibration lol
Will orient the torque arm vertical so no weight error. Cal will be a known weight at a precise distance.


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## sweepleader (Apr 12, 2018)

If the torque arm is vertical, cal will be tough as you will have to have a balanced fixture to hang your weight on or the arm holding the weight will screw up the cal. If the torque arm is horizontal, you can zero the sensor, then add your weight to it for cal.


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## Walter Glover (Apr 12, 2018)

Good point Sweep, will go horizontal then.


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## blsnelling (Apr 12, 2018)

Might be good to start a new thread for your build. I'm sure it'll get a lot of interest.


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## Walter Glover (Apr 12, 2018)

Once parts are gathered will do
Thanks


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## chadihman (Apr 12, 2018)

Walter Glover said:


> Ordered a strain gauge and amplifier to mess with as well. Should get enhanced accuracy wrt force measurement that way. Will need to figure out a calibration lol
> Will orient the torque arm vertical so no weight error. Cal will be a known weight at a precise distance.


Would you care to share the strain gauge you ordered?


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## Walter Glover (Apr 13, 2018)

Ebay bits


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## Walter Glover (Apr 14, 2018)

Chad, looking at your general arrangement sketch, it hit me that your tach is engine rpms? So do you reduce that in your formula by the 7:24 gearing? Iirc that is your sprocket setup?


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## chadihman (Apr 14, 2018)

Walter Glover said:


> Chad, looking at your general arrangement sketch, it hit me that your tach is engine rpms? So do you reduce that in your formula by the 7:24 gearing? Iirc that is your sprocket setup?


That was my first sketch and my final product was changed many ways. I read pump shaft rpms


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## chadihman (Apr 15, 2018)

The main reason my dyno sits is because I have failed to find a data acquisition system and software that fits my budget


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## Walter Glover (Apr 15, 2018)

Pad and pencil works lol


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## Walter Glover (Apr 16, 2018)

Thinking about Arduino daq into Excel...... hmmmm


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## chadihman (Apr 16, 2018)

Walter Glover said:


> Pad and pencil works lol


For a while. Pad and pencil take a time. Requires more run times to get the rpms exact and steady for recording the scale and rpms. To much time around a loaded smokey saw gave me headaches. Mostly because I was doing my testing indoors during winter months. 
I think a high tech data acquisition system would be a quick pull on the saw through rpms and done.


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## Walter Glover (Apr 16, 2018)

How about video recording?


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## chadihman (Apr 16, 2018)

Walter Glover said:


> How about video recording?


Yeah I've done that too and that made it better but the scale and rpms took time to stabilize. Then I'd record all the info from my video and put it in a spreadsheet


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## LegDeLimber (Apr 21, 2018)

chadihman said:


> I mod more than saws. This is my Kubota. Added a turbo and boosted the HP 76% Wait till the end of the video as I have some pictures of my fabrication work to fit the turbo under the hood. I'm looking into building a pulling tractor. If only I could get a turbo on a saw.



I'm still waiting for someone to hook a backpack blower to a saw.
That ought to make tuning the carburetor "fun".
Off-board Supercharger!!


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## LegDeLimber (Apr 21, 2018)

Walter Glover said:


> It appears that friction/stiction is the enemy of my hydraulic load sensor
> It is repeatable but it takes extra force to overcome the oring stiction. Will try a different seal to see if that can be corrected



I remember reading that motorcycle manufacturers were battling with stiction of fork seals, back in the late 1970's ~early 80's.
Cant recall what sort of material was deemed best for solving it.
Seemed to be a trade off of seal life vs drag.

Then we added pressurizing the air inside the forks.
..somewhere along here.....
I sorta drifted from worrying about those details and got focused more on the Female passengers, to be invited for a ride, on said motorcycles.


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## Walter Glover (Apr 21, 2018)

Spindle arrived for my dyno
Can get the sprocket made now


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## Walter Glover (Sep 25, 2019)

Sprocket blank mounted in lathe using spindle for the arbor. Made first truing cuts now to figure diameter. Looks like 6.445” diameter for 28 pins for .375” pitch chain.


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## Walter Glover (Oct 3, 2019)

Sprocket turned to diameter ready to drill for pins. Will be 28:7 for a four to one ratio. Tach on saw and torque numbers divided by four.


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## wcorey (Oct 3, 2019)

I went with 5:1 mostly for speed reduction.
Had a hell of a time trying to calculate the diameter/pin spacing, enlisted everyone I knew with any kind of math background including a calculus teacher and a nuclear physicist.
“Sure, no problem... Oh, well that’s turned into a tough one... uh, gee, I dunno...”

Ended up physically/manually laying it out, some trial and error with a chain and center punch the same dia as my pins. It’s just that last pin that’s the issue, lol.

Then after grinding down/neutering a drive chain, it wanted to walk up out of the sprocket, drove me crazy trying to figure why.
Ended up being some weirdness with that particular chain, a different one cured it.

After the all the work involved in making it, you may want to consider some type of heat treating like case hardening, plain hot rolled steel was wearing faster than I liked.


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## John Lyngdal (Oct 3, 2019)

$59 https://www.dataq.com/products/di-1100/ for data collection.

You'll still need an instrumentation amplifier with adjustable gain between your load sensor along with a voltage source to drive the load cell.
Let me see if I have an amplifier and voltage source for your project sitting on a shelf in the shop.

Even better, for $29 there is this option:
http://picom2.com/Phillips_Instruments.html
It runs on +/- 12V but a little DC-DC converter will take the +5V from the USB to +/- 12V
https://www.digikey.com/product-detail/en/xp-power/IHL0205D12/1470-3835-ND/6221040



John


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## Walter Glover (Oct 3, 2019)

Diameter that worked in the end was 6.285” iirc. Had a 28 dl chain madeup so was easy to know when diameter was right.


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## wcorey (Oct 4, 2019)

I don't remember the final numbers on mine but made a template to use as a reference and drill jig in case I ever want to make another. In practical terms an even pin count/ratio wasn't really important or necessary because you could just plug the ratio into the software and it got calculated in auto-magically.

To figure the diameter I just gave it a close estimate then turned a disk out of thin, like 14ga, steel and brought it down in .005" increments until things lined up for 35 pins.
Then went to 10ga for the jig and ultimately the two outside halves of the sprocket.

Made one for .325 and one for 3/8ths that also works for 3/8lp

Keep in mind for pin placement that your 28 pin sprocket is being driven by the chain rather than the 7 pin that's driving the chain (so opposite wear surfaces), unless maybe your going to use design specific (expensive) drive chain...


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## wcorey (Oct 4, 2019)

You might want to check out the 'saw dyno' thread on the 'other power equipment forum', goes back to 2016 or so.
Sorry I cant post links here...


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## Walter Glover (Oct 4, 2019)

Thank you Bill. Your sprocket is the way i figured to pin mine as well. Got disks nearly trued up to rotary table. Need to mount a suitable plate for the divisions then drill some holes. Have some very hard 0.156” rod here to cut up for pins. Hope that works


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## wcorey (Oct 4, 2019)

I used dowel pins, something like drill rod would likely be fine too, drilled stepped holes so the pins are captive when the halves are bolted together.
IIRC Chad had an issue with the pressed in pins wallowing out of the holes.
The pins weren't so much of a wear issue on mine but rather the edge of the sprocket plates where the chain side plates ride.


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## Walter Glover (Oct 4, 2019)

Had to make a 42 hole circle for the rotary table to allow 28 divisions. Had an aluminum casting that had issues so made a fixture to hold the sprocket disks. Worked great for indicating the disks in. Pilot hole through both plates together as they will be then seperated to drill the insides out to pin diameter. Went about 0.175” into the 1/4” plate. That will capture the pins for sure. Thanks for the tip, I like it and making the jig really made it easy.


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## Walter Glover (Oct 6, 2019)

Progress


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## Walter Glover (Oct 9, 2019)

Purchased some vintage instrumentation to see the results 
An 20 pound hanging scale and an analog phototach with multiple ranges.
The beauty of analog measurement is the ease of determining a good average or even peak value. Digital displays just don't work
for erratic values. So hope this works out eh


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## wcorey (Oct 10, 2019)

Averaging is key, whether digital or analog.
Peak doesn't mean much of anything unless it's averaged over a reasonable period of time.
Grab a handful of brake and you can see a torque spike for a fleeting moment ten times what a two second average would be and it's near impossible to nail down the rpm where it happened.


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## Walter Glover (Oct 10, 2019)

No intention of grabbing the brake as you say that proves nothing. Analog dials are perfect for determining quickly what an average value might be. 
As an electrician I never liked digital meters for moving values ie balancing a pumpjack based on motor current. Was so much easier with old school analog.


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## Walter Glover (Oct 14, 2019)

Received the scale. Big bold numbers on an eight inch dial. Commercial duty scale and accurate. Should work great for the dyno


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## Walter Glover (Oct 28, 2019)

Got the photo tach but not impressed for sustained readings so will use an engine tach with a mag pickup sensing the four sprocket bolt heads. This makes an eight cylinder tach read correctly. Had to make a little adapter circuit to amplify the small mag signal. Internet is great for finding stuff like that. Made the adapter and tach works great!
Making progress for sure


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## Walter Glover (Apr 4, 2021)

Progress today. Finished the mechanical bits and gave it a run. Many issues reared up that need fixing.


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## Walter Glover (Apr 5, 2021)

Worked on it some more this aft. 
went with a hydraulic force sensor
Made bushings to align saw in bar mount
Made a knob to fine adjust brake caliber lever
Will do some runs tomorrow if all goes well


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## Walter Glover (Apr 6, 2021)

Got it back together and did a couple runs with my 372xp kit saw. Could only get 2.85hp out of it. Best it did was 7.5 pounds torque on dyno at 2000 rpm thinking my force measurement needs help. Onwards.....,


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## Walter Glover (Apr 6, 2021)




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