firewood processor

[GAV64]

Has anyone out there built their own firewood processor, I am looking to build my own small (8 foot logs) processor. I try to use low impact practices, 8 foot logs are easy to get out of the forest with an arch causing minimal damage.I have most of the componants but I do not know how to handle the chainsaw end, where to get componants, ect... I would like it to run off a hydraulic motor bu how do you get the speed up to 10k rpm. any hel or pictures woul be appreciated. glenn

[Ianab]

Dont know anything about firewood processors... but I'd look to put a belt drive between the hydraulic motor and chain sprocket shaft to get the speed right.
My 8000 rpm chainsaw drives a 1500 rpm circle blade thru a belt and appropiate pulleys.. just reverse the idea. 1500 rpm engine and 8000 rpm chain drive?

Ian

[EdK]

I'd like to build a small one as well. I don't know how to run the saw from a hydraulic motor and I would like to learn.

My neighbor has a firewood business and his processor is home-made. I noticed that even though he made use of hydraulics for splitting and elsewhere, his cut-off chainsaw is electric. I asked him about it when I observed the chain running on the slow side. He said it is a 3-phase 7.5hp motor. It seemed to cut like the proverbial "hot knife through butter" even though it was probably turning 1750 rpm. Thinking about that afterwards I began to wonder whether there is really any need to run the chain as fast as it does on a typical chainsaw. We know those small 2-strokes make their power at 10K+ rpm. Is that perhaps the only reason why?

Maybe your hydraulic motor doesn't need to spin the sprocket at 10K rpm making up for rpm with torque.

OK - now I've revealed I really don't know what I'm talking about  :-[

[Minnesota_boy]

I think you do know what you are talking about.  When chainsaws were new to the woods, they were all geared down, lots of torque but not much speed on the chain and they worked fine.  Just had to watch for a chain to get pinched in the cut while bucking as it could set you on your butt.  All the saws had big felling spikes so you could force them into the cut while felling or bucking and your rakers could be cut way down.

[Murf]

I've helped in building a few, and I'm building one of my own now.

I wouldn't, however, based on speaking to owners of all kinds of processors, and doing lots of research, recommend using a chainsaw type of cutting operation.

The chain is the down & dirty method, but it also has lots of problems, debris, dirt and wear all take their toll, and rather quickly too.

The big circle blade is the best all-round, but is more $$$$ and is more complicated.

I'm going with a shear style of cutter, it cuts and splits in one operation and never really needs sharpening. Basically a hydraulically powered guillotine, all hydraulic and very portable.

[EdK]

The big circle blade is the best all-round...
...I'm going with a shear style of cutter

Care to explain a little further?

Thanks, Ed

[Murf]

Well, I can try, poetic license aside let's see if I can do it in less than 10,000 words since I don't have a picture yet except in my mind.

-two vertical tracks, a couple feet apart.
-heavy steel blade slids up & down in the tracks, pushed & pulled by hydraulic cylinder(s).
-infeed track, like apron chain on politician, rolls log in between vertical tracks leaving it under blade.
-blade comes down and the log 'parts company' with itself.
-block falls into a V-shaped chute which has a splitting wedge at one end and a pusher block of the splitter at the other end.
-While the block is being split down below the blade is going back up & the apron chain is feeding the log ahead to make the next block of firewood.

All controlled from an operator's station via hydraulics, or automated, in theory, all powered by a hydraulic system. Gas, diesel, electric or PTO is as easy as the rest.

[EdK]

Thank Murf. I appreciate the processor design overview. I'm sorry if I wasn't overly clear in my question: If big circle is best then why is Murf going hydraulic?

Wouldn't the big circle implementation somewhat resemble the pto firewood saws I occaisionally see?

[Murf]

Best over-all is still a compromise in some situations.

I want something smaller and more portable, I also want to be able fabricate it myself and have it very 'field service' friendly.

[beenthere]

Murf
I have heard that the forces required to slice through wood across the grain are very high. Any idea what forces will be required so size of cylinders and hyd. pressures can be calculated?  Of course it will depend on the max diam of the system, the edge on the knife, and the species of wood too.

People used to (maybe still do) evaluate wood splitters by cutting across a log of white oak to 'show' how powerful (or not) their wood splitter was. That test would slow a few of them down a bit.

[Ron Wenrich]

I worked on a Morbark processor that used a circle blade.  Your discription is fine, but you need a clamp to hold down the log or you'll be having it for breakfast.

The way the Morbark worked (if memory serves me) the firewood logs were placed on a log deck.  They were brought in to a flat belt conveyor.  You advanced them ahead to the desired length, clamped and cut it.  The saw was on a pivot, much like a swing saw and was brought up and down with a cylinder.  I believe it used a hydraulic motor with belts.  Simple operation.

We now are running a processor with a chain.  It doesn't get that dull.  We can do a couple of trailerloads on a sharpening.  It depends how much mud you want to bring into the mill.

Logs are put onto a log deck, and brought to the infeed deck.  There, a grapple grabs the log and advances it forward.  Takes a pretty long cylinder, but is pretty quick.  That eliminates the clamp, since the grapple is pretty sturdy.

You can get hydraulic motors in all types of speeds.  We changed the speed on the mill headblocks by changing the motor.  Speed can also be changed by pressure.  You could always buy a motor off of a company that makes processors.  

Most of the units I've seen run with a small diesel motor as a power unit.  

[Ed_K]

 I built a small one, made of an old truck frame. I bolted 6x6's to each side then screwed 2x4's across with slots wide enough to saw down thru at 16" which is most of my orders. On the tail end, I mounted a 3pt type of splitter, does up to 24".
 Build up some bunks even with 2x4 frame, load up some logs, roll one on and run down thru cutting to lenght. Then stack on opposite side and roll another on. When the frame is full, roll a chunk down to the splitter, and split. I also built a metal table around the splitter so the chunk won't fall to the ground. And throw on to truck.
 This saves my back, as I don't lift the big chunks. The splitter is run by an 8 hp w/barnes two stage pump. It uses about 1 gal of gas to do a cord, including tractor to load bunk, chainsaw and hydro motor.
 I also made an elevator out of a hay evevator. It works but needs hydros to run. The electric motor burned up as I ran extention cords to far and didn't have enough amps to run.

 My alternitive method is cut to 4' and split with american 4' 3pt splitter. Do up a few cords, then put into sawbuck and cut to lenght and throw on truck.

[ScottAR]

Chomper

Shear style firewood processor.  If one has a highspeed connection, the videos are impressive and show the machine quite well.  HTH

[karl]

Made a processor a few years ago- have since "upgraded"

It was a heavy duty set of roller conveyors from the off side of circle mill mounted on longer legs, used regular ole chainsaw mounted on a pivot with an adjustable stop that turned with the saw so it did'nt bind when the block fell. The block dropped into a 3 pt splitter that I activated using two detent valves so that it would split then return while I was cutting the next block.

Worked really well on the veneer mill cores that we were processing and on 12' or less straight logs.

[Murf]

BT, as you mentioned, required forces vary wildly depending on size and type of log being processed.

I have done some experimenting using a quick prototype hooked to my backhoe, a 6" cylinder with 2500 psi behind it goes through a 16" green maple without any visible effort or slowing down. BTW Ron, as long as the log is supported on both sides of the shear blade it barely moves at all, the trick is in the shape of the blade.

The chomper is of a similar design, there are several companies making the same type of thing, they are all, like a lot of other things, disproportionately expensive. They are all in the $25k range.

As a comparison, I took a drawing I made based on my research and experimenting to a friend who owns an eng. & fab. shop and asked him what he would charge for it as a 'one off' and being the first one they ever made, learning curve plus custom job, he said he would charge about $10k but only about half of that would be for the materials at retail prices. I priced what I need to make it at about $1800, not including a motor.