Home Made Saw Mill Motor

[walterjii]

Hello: I am in Las Lomas Peru, just south of Ecuador trying to help out poor farmers with logs which they can not afford to saw into posts and lumber. Am building a chainsaw sawmill just like the old circular carriage mills, but using a 20 in. saw bar and chain fixed vertical with log running past on carriage. I need help with powering the chain, what type of motor and how to drive chain. Maybe simply a motor, belt, pulley, shaft, chain sprocket system driving the chain. If you have any suggestions for me, these poor people would surely appreciate it. We do not have bundles of dollars to throw at this, otherwise we would simply purchase a portable band mill, but that is out of the question, so back to the drawing board with necessity being the mother of invention !!
Thahks Much, Walter J. Robb.

 

[MikeHalloran]

My first choice would be the engine assembly that normally comes with the bar and chain, because it already has the correct sprocket, sprocket bearings, a clutch, and an automatic oiler. That last is most important, because a saw chain will cut green wood for less than a minute without oil before it turns to junk.

Given that you want the bar vertical, I'd be inclined to set it up with the drive sprocket at the top, so gravity will help you keep it clear of chips ... of which there are a lot.

You are of course aware that there are simple chainsaw mills for sale for not much money. The ones of which I am aware comprise what may be a generic chainsaw, mounted with the bar horizontal, traveling on a carriage along a lightweight track held parallel to the top of the log. Wedges or shims are slipped in behind the sawbar as the cut progresses so the sawn board doesn't pinch the bar.

Moving the saw and carriage over a stationary log has to be easier than moving a heavy log past a stationary saw. It also distributes the chips, of which there are a lot, over the length of the log instead of piling them up in one place. Moving the saw also allows your chip- shoveler to work remote from the chain, reducing the number of people in the vicinity of the teeth.

;---

Quick course in chainsaw safety:
Q: What's the difference between a leg, and a log?
A: The saw ... doesn't know.






Mike Halloran
Pembroke Pines, FL, USA

 

[MikeHalloran]

If you insist on using an electric motor, then the stationary saw makes some sense. I'd still suggest putting the drive sprocket at the top.

You'll have to adapt the sprocket or a saw's sprocket shaft; the sprockets are specialized for saw chain.

I suggest you still include an automatic chain oiler, and a centrifugal clutch or a v-belt drive, so as to reduce the chance of fracturing the chain when it snags a knot or a nail.



Mike Halloran
Pembroke Pines, FL, USA

 

[waross]

A couple of points; The chain pulls the chips towards the sprocket.
The centrifugal clutch won't do much for an electric motor. It only disengages when the motor slows down. Great for the original motor with a throttle but not much good for an electric motor.
If the chain jams, the clutch will slow the motor down to almost stopped, the motor and the clutch will overheat rapidly.
You may be able to salvage the part of the chainsaw case where the bar bolts on, and have a new shaft machined to replace the original crankshaft. Then you can use the clutch. Not so much for a clutch but the drive sprocket and clutch drum are often one piece.
I have been involved with mills and cutting in Central America for a number of years. I hope that you are aware of the horrendous waste when cutting lumber with a chain saw. Even a circular saw is much better than a chain saw and it is easy to set up.
Consider an alaskan Mill Easy to copy.

http://www.granberg.com/

You will do better with ripping chain.

http://www.granberg.com/ripping_chain.htm

I have seen several large mills fold up. To be competitive with a chain saw you have to get the logs free, and stealing power would help a lot also.
And remember that the first time someone forgets to fill the resevoir on the chain oiler, the bar is done. It will still work for quite awhile as a cross cutting saw but its days as a ripping bar will be over.
Your energy consumption is almost directly proportional to the width of the cut. Your energy requirement for cutting with a chain saw may be 5 times or more the energy requirement for a band saw.
There are still some cutters making lumber here with chain saws. They square the log free hand with a chain saw and the mill that buys the timber for re-cutting also has to buy the side lumber. Most of these operations have been replaced with portable band mills. Some chain saw cutting is still done in remote areas where there are no roads. This is for high value hardwood which is brought out on mule back.
Years ago a friensd of mine was involved with an operation that was taking the mules 8 hours one way to deliver the mahogany to the nearest road.
Good luck.

 

[itsmoked]

I can't think of a worse way to cut wood!

All the points waross makes should be repeated.

1) No oil - one time.. Toast.
2) Massive waste of wood due to kerf width.
3) Excessive waste of energy.
4) Dangerous flying broken chains.
5) Hardest of all saw blades to sharpen.
6) Because of the unreasonable width of the kerf, running into odd parts of wood,(like knots), requires extremely large fast variations in cutting pressure.
7) Hundreds of moving parts involved instead of a number you can count on one or two hands.
8) Will be a maintenance nightmare of epic proportion.
9) Because of the large cutting pressure everything will need to be built with heavier more expensive material.
10) No inertial advantage as provided by a rotating blade or band saw wheels.

Start with a junker band-saw or make one from scratch they are superior in every respect. That's why all the portables are made in that style.

You could probably even drive a band-saw blade with a couple of car tires and some belts. Adjust the belt tension with a tire pump.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com