Coarse Cutting Wood Chippers

Yes Brian, I understand its function is like Wayne’s, just thinking about what Steve U said about shear blades and if it could be possibly scaled down and more compact to run from a small-ish engine if you didn’t have a PTO.

Matt. I agree with the triangle design. I would suggest designing in a ledge for the cutting blade to butt up against so the ledge takes the cutting force instead of the fasteners that hold it in place. All the big hydraulic metal shears I worked on use this principal. With the triangle design you would have more room to put reinforcement for a removable blade. Think along the idea of big sicsors with replaceable blades. Another thought if you used a v notched blade wouldn’t it cut down on the forces required to cut the material because you aren’t trying to blast thru the whole thing at once?
For what it’s worth

Here’s another one that’s pretty neat.

Steve G, I think Wayne’s chunker could be run from a small engine. A centrifugal clutch and jack shaft with some weight on it should work.

Hello Marvin,

I agree , I don’t think my chunker is using more than 5 hp. The little tractor that powers it is rated at 20 but it just idles along.

That’s really encouraging, Wayne. I have a spare 14hp Changfa-clone diesel engine as well as a couple of gasoline horizontal shaft engines. I also have the dually rear end out of a Class C motorhome. Adding some flywheel weight to the driveshaft, do you think this would work? I can see a belt drive arrangement so I could play with rotation speeds.

As soon as I get time I’ll put together a CAD model of the WK and the other that was posted above. I have sourced some parts to build this pretty cheap I think.

What is the my target RPM so I can source the gearing to make this work?

I’m not sure of the speed, you may need to watch a few videos to get an idea. I got a response back from Tech Mark/ Rojek.

Here it is:


Thanks for your call yesterday, and for your patience while we got our server back up and running.

Attached is a product brochure for the Rojek Wood Crusher. We stock the DH10S gas operated model in our Little Rock, AR warehouse. The price on this unit is $6150 less 15%. (We’re running this sale on all in-stock Rojek equipment.)

Please let us know if you have any questions or need additional information.


Jillian Jackson-Reeves
Tech Mark, Inc.
7901 Industry Drive
North Little Rock, AR 72117-5317
Tel. 501-945-9393

I posted the brochure here:

Matt, I think these are worth taking a look at. Pretty simple and seems like it could handle large or small stock. About 10-20 rpm judging by the videos.

I think Wayne said his run at 60-90 rpm

I just took a peak at the spec sheet that Derek had posted under “member files”. One big thing to note is that their self-powered gas engine is only a 5.5Hp Honda engine. Good to know for those building their own.

Hey Steve,
I’m right there with ya on that one.

This would be my first choice for a build.
The adjustable auto feed is what I like about it.
Once it gets hold of wood, you can back away and let it take the pounding… Much less possibility of injury and less operator fatigue.
I would like see some ideas for the in-feed section adapted to Wayne/Jussie’s Chunker.
While slower than the Reback style, I believe it would need less maintenance and more reliable. And… Deal with larger wood.

Yeah I like it:)

Hi all,
I liked the feeder shut off feature on the linkage bar in front of the shoot at 1:50 he shuts the feed down and then pulls a lever to eject it. Pretty fancy but great for those narly nasty pieces or emergency.

I was also thinking instead of a conveyor have it despense into a “fishnet type of bag” that would let the wood air dry - in the bag. Some roundbalers have this type of plastic netting that they use to bale instead of string but I don’t know if it would be strong enough for jagged edged wood. Just me brainstorming again I hate moving wood anymore than I need to. LOL

Well I started on a drum spiral blade system like the WK and similar. VEK has given me an idea how to construct this. I know from this gasifier that the 8" wheel will fit very snugly into the 5 gal. Job Smart air tanks. So you could weld this wheel into the cut apart tank and then cut the spiral edge in it. The only thing is this tanks wall thickness is 14 ga. This drum spiral cut will be small 9" diameter and the spiral pitch is 6". This should give it a higher integrity and will not require a lot of torque. I wish I could find something with a thicker wall. The inside diameter needs to be 9.25" so if any one knows of an existing drum or tank with this dimension let me know.

I going to source more parts for this thing and give it go. If the thin walls fails then Ill have our fab shop make a thiker one for me. Our roller will only roll 14 ga. 12 ga aint gonna happen.

Matt: Would an air tank be strong enough grade of steel for such a use? I know the brake drums that Wayne uses aren’t “tool grade” by any means, but I’m fairly sure they are significantly harder steel than the air tanks I’ve seen. My guess is that the air tank metal just won’t cut it (full pun intended).

The wheel I used is a trailer wheel from Tractor supply, It is an 8 x 3.75 wheel, you can get them in 4 or 5 lug. I was thinking of modding a trailer axial and gearing it down with a belt drive system from a 5 or 8 hp engine.

If I were to use a transaxial from a tractor I would couple it to a shaft that would take the actual load. I don’t know if the transaxial would hold up, but I don’t know never tried it. I happen to have an old Honda tractor here with an intact trans on it. The rest of is junk, I was going to make a go cart out of it, but im thinking wood chunker now. lol

Are those diameters the ID or OD? if the 10" pipe is the OD the wheel will fit perfect in with the 3/8 wall. I could also just reinforce the tank with some 1" flat bar and rap it around at the edge to give it more integrity.

Hey Guys
I do not think a riding lawn mower system rear axle will take the Grunt needed for a very high torque spiral cutting system. I think it would take a minimum of a full floating bearing 3/4 ton rear axle differential. Anyhow both of these are still too high of gear ratioed at 3 to 1 and at best 4 to 1.
Mr Wayne is using a 6 to1 HD truck axle direct 640 RPM? 1000 RPM? PTO driven.
Finn Jussie, TerryL refered to, used a slow speed trasit bus HD axle then with a pinoin shaft mounted transit wheel and rubber tire friction wheel driven by an AC electric motor. More down speed torque multiplication here.
These are your know works systems.
Now in the manufactueres video TerryL put up this is speed gearing down, torque multiplied by the very heavy chain drive to the cutter drum pictured.
This is your solution to try on downsizing. Thanks TerryL for this. I just happen to have an old Ford 3/4 ton axles I have been saving back looking for this solution for my Doug Fir limb wood.
Steve Unruh

A potential source of wood in the northwet if you don’t have a sawmill.

Regards, Tim J

Yeah I think Im going to stick to my plan with the trailer axial. I can reinforce the tank steel to take the abuse and the axial will go though the spiral cutter so there is a heavy duty bearing on each side. I can reduce the engine down to a low RPM with gearing. I was thinking belt drive would be better than a chain system if things get bound up the belts could then slip. May need multiple belts though.

Is there anyway to use the rear axle of our own rigs? That way we would not have to get another motor. anyway could just bolt it to our axles I read some other post before mine and sounds like it might not work.

been lurking on this thread for a bit and eagerly watching the brainstorming process and the last post finally made me decide to add my inexperience to the mix.

I’ve been in the process of fabricating a chunker driven off my back wheel of my wood powered truck. I just got the shaft keyed last week and hopefully will be able to bolt it all together, get the sprockets and chain on this week and see if it works. I may be able to post video of the event.

a little more information found here:

I will hopefully also be updating the blog with some video as well.