Problem with my Double bar 10 HP elect.

[Javillonian]

I have fun thinking out of the box, I get an idea and I tend to jump into the project just to see if it will work. So last winter I put together a mill, here's the basics- I put two 36" bars together with a spline pressed into their groves to hold them on the same plane, I did this because I wanted to use large (5+") sprockets and a 1750rpm motor. This would slow the sprocket rpm down and bend the chain less as it rounds the sprockets, also allowing me to use a slow rpm motor to achieve a high chain speed. I already had two 10 hp electric motors from another project and wanted to use them. It's a stationary setup and the log rolls thru it on a separate track. Large threaded rod on all four corners lifts the bar, motor and assembly up and down via a motor. An electric valve opens when the motor starts and gravity feeds the bar with oil. A hand crank pulls the log thru the cut. Using .404 chain, I've tried a full skip and a hyper skip 10 and 0 degrees.
So I finally got time to test it out. It cuts like crazy, but it wants to bind up, I made about 20 cuts on a couple 24' logs with almost no problem then the next log just wanted to bind every 10 inches, if I push the log back away from the cut it blows out a puff of sawdust and then cuts great again for another foot before binding again. It seems obvious that the pressurized sawdust behind the chain is being forced into the space between the bar and the slab of wood and eventually gets tight enough to stop it. The teeth on the chain stick out a good sixteenth of an inch above the bar so that leaves a pretty big space for the dust to get into, and then having a double wide bar complicates everything. If you've ever watched a snowplow going down the road at speed and saw the snow flying of the plow, well I think if you could look into the kerf while it's cutting, it would look just like that, throwing the dust right into that space above the bar. So I'm stumped, I'm thinking of trying to attach a thin strip of metal to the bar right behind the chain to reduce the size of that gap and hopefully minimizing the amount of dust in there to a point that it will be drug of the back and not pack. Anyone ever have a problem like this??? Thanks, 1st ever post

 

[BobL]

If it's binding on a 24" log the problem is only going to get worse with wider logs
Sounds way more complicated than is necessary.
The way I would handle this motor is to leave the motor at standard revs and use a standard bar and maybe a 10 or 11 pin sprocket
Then test cut using a 32" log repeated drop the rakers till the motor starts to stall and then shorten the cutters a touch..
This setup will utilise the torque of the 10HP motor and cut like crazy.

 

[Javillonian]

If it's binding on a 24" log the problem is only going to get worse with wider logs
Sounds way more complicated than is necessary.
The way I would handle this motor is to leave the motor at standard revs and use a standard bar and maybe a 10 or 11 pin sprocket
Then test cut using a 32" log repeated drop the rakers till the motor starts to stall and then shorten the cutters a touch..
This setup will utilise the torque of the 10HP motor and cut like crazy.

Hey thanks for commenting, what you suggest I'm going to use as a last resort, I really like the large (22 teeth) sprocket, It has to be much easier on the chain, and the nose sprocket is also a 22 tooth so also much easier on the bar. The bar is a hardnose because the chain never touches the nose. I like what you say about "utilizing the Torque" , I've actually been thinking about slowing the chain down, I'm thinking the pressure produced behind the cutter teeth may be contributing to my problem. But one thing at a time, I picked up some 20 gauge (.036) stainless today 3/4 wide and tomorrow I will spot weld them to the front of the bar and see how it effects it. Thanks

 

[BobL]

It has to be much easier on the chain, and the nose sprocket is also a 22 tooth so also much easier on the bar.

I don't believe it matters,
Lucas slabbers up to 30HP use conventional chain saw bars and nose sprockets - it makes no difference to the chain or bars.
An 880 Stihl is 8.5HP and runs at really high speed (10k rpm) on an 8 pin sprocket which would be the equivalent or running a 46 pin sprocket at 1750 rpm - I have seen not chain issues with conventional bars and sprockets on these saws at these chain speeds.

 

[Javillonian]

Thanks again Bobl, 1st my sprockets are on spindles, driven off 3 belt sheaves, I set the diameter of the sheaves to give me a chain speed a little above an 8 pin sprocket spinning at 12300 rpm. This is the maximum rpm of my 440 stihl, although when under load in the wood I'd guess the 440 runs closer to 8000, it's really clear when watching the two, the constant speed of the electric motor really explodes the chips. Keep in mind that if you were to replace a 10 hp electric with a gas engine you would need a 20-30 hp engine depending on where you read, I've read as high as a 4 to 1 ratio. So this thing would be 2-3 times what an 880 is. So I like my big sprockets, when I look at those little sprockets I just can't imagine putting that big HP thru them, I know they do, but it just looks wrong. My real problem I'm trying to solve is those damn chips clogging the kerf!

 

[BobL]

. . . . I look at those little sprockets I just can't imagine putting that big HP thru them, I know they do, but it just looks wrong. My real problem I'm trying to solve is those damn chips clogging the kerf!

Well that's what the big Lucas slabbers use on their bar noses and they run up to 72"+ bars and 30HP motors. They just drop their rakers and they cut like a knife though hot butter.. I've even heard of one bloke who almost completely removed the rakers off one of his chains and it cut like crazy without jamming..

The other way I'd look at this is if a mill is tied to an electric power cable with a connection big enough to run 10 horses I'd be doing it with a band mill rather than a chain, It wastes ar less wood and makes less sawdust. I also realize people often work with what they have on hand and sometimes it is the cheapest way to get to a target.

 

[Javillonian]

I actually have a large vertical band with 36" wheels and a 20 HP electric motor. It has two 20' rolling tables, one in front and one behind the blade on 40'of track. My plan is to break down the logs with the chain saw mill into cants and then run those thru the band to make boards. I want my boards to be straight and uniform. On large cuts this chainsaw setup cuts dead on, no wandering. And then when I transfer the cant over to the band it cuts the thinner cant into perfectly straight boards. Again I'm just playing here, repurposing some old stuff I have.

 

[blades]

Rakers- misnomer actually are depth of cut limiters on a chain. rakers are on flat saw blades and circle saws of combination types. and those do a clanout of the kerf.
Rather than using skip sequence a true milling chain ( more room between cutters) might be a better choice more room in those for sawdust. another option is to take a standard ( full comp?) chain and remove the top plate from every other cutter per side leaving just the side plate. leaves alot of room for swarth. Yes, they are slower cutting but not that much.

 

[TRTermite]

Cottonwood needs a sharper (circle) Blade than Oak because It has to be cut and carried out of the cut NOT CHIPPED and carried out of the cut .. To small of a blade without the proper RPM will plug the gullet and create a myriad of issues. Is your chain cutting large enough chips so it is carried out or dust that is sliding by the gullet Just FOOD for thought.

 

[chunky]

Cottonwood needs a sharper (circle) Blade than Oak because It has to be cut and carried out of the cut NOT CHIPPED and carried out of the cut .. To small of a blade without the proper RPM will plug the gullet and create a myriad of issues. Is your chain cutting large enough chips so it is carried out or dust that is sliding by the gullet Just FOOD for thought.

I guess i missed where it was type of wood. I did a cottonwood a couple months ago and it didn't matter wht chain I used, it was a pita. I went from my scrap chains, my good chain, to brand new chains and it didn't matter which I used. I got home back to my oak and those same chains cut it like butter compared to the cottonwood.

Sent from my SM-A526U using Tapatalk

 

[TRTermite]

I guess i missed where it was type of wood. I did a cottonwood a couple months ago and it didn't matter wht chain I used, it was a pita. I went from my scrap chains, my good chain, to brand new chains and it didn't matter which I used. I got home back to my oak and those same chains cut it like butter compared to the cottonwood.

Sent from my SM-A526U using Tapatalk

I was using cottonwood as an example for the chip.dust concept.

 

[blades]

you bet. op said dust but long strings are another problem they pack up quick , so you need lots of room between cutters an lots of room out of the saw. Cutting with linear growth of the wood will give long strings in just about anything. ( lots of people call that noodling) best choice for this oem ripping chain or homemade version I listed before.

 

[TRTermite]

you bet. op said dust but long strings are another problem they pack up quick , so you need lots of room between cutters an lots of room out of the saw. Cutting with linear growth of the wood will give long strings in just about anything. ( lots of people call that noodling) best choice for this oem ripping chain or homemade version I listed before.

I have yet to chainsaw mill a log but have freehanded a few boards to get some lumber for hickory handles and things There is day and dark difference between Band saw/circle/chainsaw milling and yet there is a lot of common concepts to apply I am still learning and forgetting.

 

[BobL]

I actually have a large vertical band with 36" wheels and a 20 HP electric motor. It has two 20' rolling tables, one in front and one behind the blade on 40'of track. My plan is to break down the logs with the chain saw mill into cants and then run those thru the band to make boards.

With such a big bandsaw mill available it sounds like it would be more capable of breaking down logs than a mill with a 36" bar. By the time bar holding is taken into account there will only be about 30" of cay available. Does it have something to do with the weight bearing capacity of your rolling tables?

I want my boards to be straight and uniform. On large cuts this chainsaw setup cuts dead on, no wandering. And then when I transfer the cant over to the band it cuts the thinner cant into perfectly straight boards. Again I'm just playing here, repurposing some old stuff I have.

Sure - I get this. I do this quite a bit myself but not so much on a large scale as yours
I'd be really interested in photos of your mills and also the finish of the cuts.

 

[Javillonian]

With such a big bandsaw mill available it sounds like it would be more capable of breaking down logs than a mill with a 36" bar.

It's big but kinda wimpy, after about 12" I run the risk of deflecting on hard spots, bought it from a meat packing company 30 years ago, they used it to split cows.

Does it have something to do with the weight bearing capacity of your rolling tables?

Not really, just not configured to do it

I'd be really interested in photos of your mills and also the finish of the cuts.

I don't have any of finish cuts but I think I have some of when I was moving it from one shop to another. I'll finish this post and then try in another post, not really sure how to do it but I'll give it a shot.
So yesterday I tried cutting with the bar that I added the stripes of metal to. I still had the same log chucked up so I started where I left off, if you remember it was jamming every 15" when I quit. Well this new bar cut four boards (11') without a problem, then tried to jam twice on the fifth board. It obviously is getting to many chips behind the chain and on top of the bar and causing the jam, which is aggravated by the two bar system. So I'm done, bad idea, learned a lot about the dynamics of chips and dust around the chain. So I ordered up two new sprockets , a 15 and an 11 tooth and started converting over to one bar, it's pretty easy really. I'll get about 3400 feet per minute out of the new setup but it'll have more torque, so I'm thinking I'll take the rakers down to get it cutting good. I'll update when I'm up and going.

 

[Javillonian]

Hope these come thru ok

 

[blades]

NIce rig

 

[TRTermite]

Brain Fog is clearing up fast. I saw the picture this morning and your 2 blade concept went un noticed , Had to be due to my morning coffee not kickin' in yet. You do have a lot of effort involved.
Now I gotta go back and scrutinize a bit Like post #16 says "NICE RIG"

 

[BobL]

Thanks for the photos.

The mill looks like it's not on wheels ? Still to come? or does this mean the logs are rolling under the bar instead of the bar rolling fast the logs? You much have a lot of space to be able to do this.
If you are worried about the lightweigtness of a regular CS B&S then you could consider a harvester bar/chain/sprockets. These things have enormous grunt. I realize you want to use up what you have but those bars look brand new to me?

 

[Javillonian]

Bobl, here's some new images that should help explain it.