FATGUY
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this has the makings of one of the greatest build threads in AS history. 
Chainsaw dynometer build.
- Thread starter chadihman
- Start date
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Will you be able to graph the power curves or just show peak Tq and Hp figures?
Mastermind
Work Saw Specialist
srcarr52
We can't stop here, this is bat country.
Yes. I think you have the right idea. Since you'll probably be using a S-beam style load cell mount it with heim joints on both sides to keep it from getting any load other than in the principle direction.
chadihman
Addicted to ArboristSite
Well for right now I'll just pull the saw down to different rpms and record the torque. Note paper,pen and a calculator will be used to start. That is unless someone can lead me in the right direction to hooking this all into my lap top. I'm not very good with computers. If this all works as planned it will be high tech some day
chadihman
Addicted to ArboristSite
Yeah I'm still in the works for getting a load cell. There pretty pricey. The load cell is the most expensive part so far. This might sound cheap but I found an accurate mail scales that measures from .005 lbs to 7 lbs. I might just start with that untill I know for sure its gonna work. I'm almost positive it will work but this is a prototype and I'm sure there will have to be changes after the first test
Last edited:
LegDeLimber
Addicted to ArboristSite
My initial thinking was to drive the pump output through the variable restriction (needle valve)
put a press gauge T-ed off the line between pump and valve.
from valve go to proper type flow meter (ball type?)
{ think like your argon/Co2/ helium meters used for welding setup works. }
from flow meter to reservoir, T-in another press gauge in the line from meter to reservoir.
Would also put a temp gauge at inlet side of restriction and maybe one more somewhere.
( I just like lots of data)
the torque arm holding the pump, you could put it braced on some strain gauge
to feed Your recorder if wanted.
or you could load it against some sort of a scale (bathroom type , cheap!),
known weights balance type.
or pick out a fancy gauge from some electronics outfit.
of course you'll want a recording type tachometer in the mix.
wish i was back in a machine shop.
put a press gauge T-ed off the line between pump and valve.
from valve go to proper type flow meter (ball type?)
{ think like your argon/Co2/ helium meters used for welding setup works. }
from flow meter to reservoir, T-in another press gauge in the line from meter to reservoir.
Would also put a temp gauge at inlet side of restriction and maybe one more somewhere.
( I just like lots of data)
the torque arm holding the pump, you could put it braced on some strain gauge
to feed Your recorder if wanted.
or you could load it against some sort of a scale (bathroom type , cheap!),
known weights balance type.
or pick out a fancy gauge from some electronics outfit.
of course you'll want a recording type tachometer in the mix.
wish i was back in a machine shop.
srcarr52
We can't stop here, this is bat country.
I was going to convert mine to data acquisition soon. I'll let you know what I come up with. I know turn key software/hardware starts at about 2k for small engine dynos.
chadihman
Addicted to ArboristSite
I'm wandering if I could make a small business with this dyno. I could charge a small price for every saw that goes on the dyno. Send me your saw and I put it on the dyno and we compare everyone's saws. This would be awesome for a GTG with all the different saws. Then we could prove who has the strongest saw and who's full of bs. Alright Chad your getting ahead of yourself.
chadihman
Addicted to ArboristSite
this has the makings of one of the greatest build threads in AS history.
I don't know about that. There's some really nice log splitter builds on the firewood forum. I thought about building a log splitter but what the heck I can buy one for the price I'll get into making one. I make things I can't buy.
Mastermind
Work Saw Specialist
I want one......fancy ain't me so I'm yer man.
We already know who BS is.
I wish you luck on your dyno. Last year I experimented with making a hydraulic retarted load dyno with a simple beam scale for measurement.
I was not trying to get HP numbers. Just make a scale for a base line reading, then measure percent of gain or loss from any changes to the motor.
I machined a new driven gear for the hydro unit with the same pressure angles as the drive sprocket on my Poulan. I then ran into chain problems that had me scratching my head.
The problem is in the design of chainsaw chain. The drive links are designed to have only one drive side. Not a drive and a driven side. The chain is driven by the sprocket around the bar, the load is on the outside of the chain, not on the inside. The chain is not designed to transmit power to a driven sprocket. I had problems with the drive links. At times it would break the chain, kinda gives you a cheap thrill, it makes a lot of commotion real fast.
I had considered making a pin sprocket for the hydro unit. This would put the load closer to the links rather than down on the drive teeth. Or maybe adapting a roller chain with a new dedicated drive sprocket.
Just giving you something to think about. Breaking chains when the load came up got old. I got busy on other projects and shelved the dyno. After reading your thread I might drag it out of the back shed and tinker with it.
Good luck on your adventure.
I was not trying to get HP numbers. Just make a scale for a base line reading, then measure percent of gain or loss from any changes to the motor.
I machined a new driven gear for the hydro unit with the same pressure angles as the drive sprocket on my Poulan. I then ran into chain problems that had me scratching my head.
The problem is in the design of chainsaw chain. The drive links are designed to have only one drive side. Not a drive and a driven side. The chain is driven by the sprocket around the bar, the load is on the outside of the chain, not on the inside. The chain is not designed to transmit power to a driven sprocket. I had problems with the drive links. At times it would break the chain, kinda gives you a cheap thrill, it makes a lot of commotion real fast.
I had considered making a pin sprocket for the hydro unit. This would put the load closer to the links rather than down on the drive teeth. Or maybe adapting a roller chain with a new dedicated drive sprocket.
Just giving you something to think about. Breaking chains when the load came up got old. I got busy on other projects and shelved the dyno. After reading your thread I might drag it out of the back shed and tinker with it.
Good luck on your adventure.
chadihman
Addicted to ArboristSite
Yeah the chain crossed my mind. I got a 16 tooth 3/8 pin type for the driven end. I'm hoping that works if not I'll make a custom chain that does work. Maybe every other drive link could be put on backwards. There's something that will work. Baileys has special drive chains for saw atachments.
LegDeLimber
Addicted to ArboristSite
Yeah, once was trying to recall what chain etc was used with
the old weedbeater attachment for poulan saws.
been a while since I ran all tangents in the brain, so some (not so small) details fade.
keep it going guys, hopefully someone will pile it up and impress us!
the old weedbeater attachment for poulan saws.
been a while since I ran all tangents in the brain, so some (not so small) details fade.
keep it going guys, hopefully someone will pile it up and impress us!
srcarr52
We can't stop here, this is bat country.
You're going to need something more like a 25 tooth sprocket to keep the hydraulic pump in its recommended RPM range.
ozflea
Good ol' BP Zoom 25-1
You could use the sprocket and drive chain of an Atom borer they were available in 1/4", 3/8, 404 pitch
LegDeLimber
Addicted to ArboristSite
Hmmm, infrared thermometer & stop watch.
Rev'er up and slap the chain brake!
Then time the temp rise.
Rev'er up and slap the chain brake!
Then time the temp rise.
Dave,
There is saw chain available which is used to run a winch and this may work for your application. Take a look at a 'Lewis' winch.
chadihman
Addicted to ArboristSite
From a 6 tooth drive to a 16 tooth driven is a ratio of 2.67:1 so if the pre loaded engine rpm is 12000 the pump is 4500 rpm. Max rpm of my pump is 4000 rpm. I'll be pushing that a bit. Most saws get there max torque at 9600 rpms or lower. 9600 on the saw would be 3600 rpm on the pump. I'll just start the saw on a slight pre loaded setting. The 16 tooth sprocket I have is 3.5" so its perfect for matching the cut off bar I'm using.
