harvester sprocket

[bstall]

If i run a harvester sprocket do i need to run a harvester bar or will any bar work okay.

 

[redprospector]

Depends on the pitch of the harvestor sprocket, and it's diameter.
If it's .404 you should be able to run a chainsaw bar, if the tail of the bar is big enough to match the diameter of the sprocket. You may have to cut the tail of the bar to match the sprocket, like on a race saw.
Either way, you'd better have one heck of a saw to pull it.

Andy

 

[Brmorgan]

Either way, you'd better have one heck of a saw to pull it.

Andy

If I'm not mistaken he was asking in another thread about building a CSM using a 4-stroke B&S type engine, so that probably wouldn't be a big issue. It would sure suck if you DID have to use a harvester bar, as I'm pretty sure the smallest gauge of harvester chain is .085 or something like that.

But for my money, I would use pulley ratios to speed up the chain, and just use standard sprockets. Much cheaper and more versatile. With an 8-pin .404 it doesn't take much to get that chain moving pretty fast, and I'm pretty sure you can find 9-pin .404 though I couldn't tell you where. 9-pin .375 is easier to get though.

FWIW the 4-stroke CSM I built a couple years ago used a jackshaft system instead of lifting the whole powerhead up and down, and I could never get it to work well as far as being able to move the sprocket up and down the jackshaft easily and freely. I plan on rebuilding this summer and will most likely make the whole powerhead movable.

And yes, if you do use a harvester sprocket, grind the bar down to where it's the same width as the diameter of the sprocket or else the chain will want to derail a lot easier. That was one of the problems I had with the one I built - the sprocket was too far from the bar when tensioned and the chain would come off as soon as it bit in and started to stall out.

 

[bstall]

Thanks Brmorgan thats exactly what i was looking for,whether or not the bar had to be at least the same width as the diameter of the sprocket.The reason i want to use a harvester sprocket is because it gives me more mounting options.I also plan on leaving the motor stationary and with the design i have come up with it will be a lot easier to use this type of sprocket.oregon makes a harvester bar for .063 chain that isnt very expensive.

 

[redprospector]

I'm running a .063 Carlton harvestor bar on my bike saw.
Just make sure the tail of the bar matches the sprocket. It'll still take a pretty good sized 4 stroke to maintain chain speed in the cut.

Andy

 

[Brmorgan]

Thanks Brmorgan thats exactly what i was looking for,whether or not the bar had to be at least the same width as the diameter of the sprocket.The reason i want to use a harvester sprocket is because it gives me more mounting options.I also plan on leaving the motor stationary and with the design i have come up with it will be a lot easier to use this type of sprocket.oregon makes a harvester bar for .063 chain that isnt very expensive.

That's good to know. I just couldn't imagine a big processor running .063, but maybe there are smaller Bobcat-sized machines you can get a harvester head for? Hell, if a harvester can run .063 then I definitely won't worry about the .050 on my 660!

Just out of curiosity, what are the bar/sprocket/splined shaft worth anyway? I've never checked such things out. I tried keeping the engine stationary too as you plan on doing, but I just used a standard keyed shaft, and couldn't come up with a good way of mounting the sprocket to that shaft such that it would be both secure when cutting yet easy to move up and down. I never did get that figured out well, but I have some ideas for a different approach.