I keep seeing videos and photos of wood chunkers that have a rotating blade. Here’s one:

Are you guys making those blades or is that a particular machine that already exists? It seems like you could fab that blade from a tire rim or similar cylinder.

Hello Abe and welcome to the site .

In the upper left corner of the page you can type in chunker in the search box and a lot of chunkers will come up that folks on the site have built .

Below are a couple of videos of my chunker.


Thanks, Wayne. I’ve been lurking on here for a long time, and I was on the Yahoo group, as well.

I am familiar with your chunker, it’s one of the ones I was referring to. Did you fab that blade or did it come from existing machinery?

Hello Abe,

It is the wheel that was original on the axle, I just cut a section out of it to form the cutting action.


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ok, cool. yeah, that’s what it looks like. do you have to sharpen it periodically?

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Sharpen once or twice a year , about a five minute job if I have the hand held girder handy .

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yeah, it’s a really nice and simple design. I had contemplated a wood chipper, but after seeing that, I may just build one of those. I think I may have everything I need already laying around here!

Are there any alternatives to getting a big truck axle? I would like to build one but getting a truck axle is not cheap if you have to go and buy one.

Jonathon Collins made one out of a lighter car axle here

He shows his rack and pinion splitter first and at about 3:20 his chunker.

Good Morning Gary,

I pulled up "wood chunker " on you tube and there are several videos and I think most are on the DOW site but easy to find on YouTube.

First we need a LOT of shearing force , there is no way around that. Next it needs to cycle at a comfortable speed for chunking.

Tom Collins shows how he design a chunker on his farm tractor. Patrick Johnson shows how he built his from scratch with a big shaft and flywheel.

If one has enough flywheel you can get by with very little horse power ( 5-10 maybe less)

I think Tom Collins approach is the less expensive and quickest to build because he is using the tractor that he already has. On the same note is Perter Coronis . Easy to build but using the equipment he already has.

In my case the truck axle was the best approach ( should be able to buy at a scrap yard for the weight.) Included are the cutting knifes with three spars ( rims) Flywheel and a spare ( brake drums) . Also the gear reduction is about a 6 to 1 so the flywheel is spinning about 400 rpm to make the cycles work out good.

I think the axle wood chunker could be powered by an electric or small gasoline motor . It works out nice for a small tractor just above an idle with the high speed pto. The tractors with the 540 rpm pto will have to run much faster and I don’t think they would be as efficient .

Hi fellow wood gassers
here is my chuker in action.

it shows the latest blade profile, which works very well.
Thanks to all the guys for their input during construction.

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Thanks Patrick,

Looks good !!

Lookin good Patrick. Did you do anything with the motor that you thought might be under powered? Looks like it chunks right through just fine now. Is that your woodgas generator I hear in the background? Where did you find the dry wood?

Thanks Wayne,

I don’t have a tractor but I do have a large walk behind rotary hoe with a 14 HP Diesel motor that I would like to use. It has a heavy flywheel on it also and would probably work with out running it too fast. There is no PTO like a tractor just belt drive but the right size pulley on the truck axle would work, it has full power at 2200 RPM, at 1500 it still makes plenty of power.

Thanks for the scrap yard tip I will try that.

Hi Don
Same motor, just different blade profile.
No gasifier not running. Been chunking off cuts into boxes, and stacking them.
Not a single piece of dry wood any where, burnt it all!
I could defiantly use a bigger motor, but once you get the hang of it, as with every thing 75% operator, my girl can chunk 250 kg in an hour, with very few hang ups!

Howdy Patrick,
That thing is awesome! 250 Kg an hour!
I like it, How big green wood can it chunk?
Did you change the shape of the cutting edge as well as angle?

I’m cutting 27mm x 76mm slabs, the biggest is 50 mm x 76 mm but you have to give the chunker a breather after two cuts to get back up to speed. My mill produces a lot of small slabs, so instead of fighting the chunker it’s easier to select the right wood for chunking. Both the blade is only sharpened on the back of the blade and I cut the blade so the cutting time was less and the window was bigger, I also moved axle as close to the anvil as possible.


Thanks for the update, I may go that route on the next one… I like it.

Hi gang, I guess I’ll put my wood/fuel processing system up here, maybe it will help someone with ideas. It’s not a “chunker.” well maybe it is. I don’t know, It does make chunks, I’ll let you guys decide!!! herb

Pic 1 old bandsaw reworked to cut 3" long logs, cuts a 20" log in about 2 mins. Takes about another minute to move log forward 3" and “cinch” down
Pic 2 homemade “drop hammer” for splitting
Pic 3 lift wheel at bottom of stroke soon to hit lift lever hook
Pic 4 Lift wheel at top of stroke about ready to trip/drop
Pic 5 half hp motor
Pic 6 pile of chunks, drops about one time per second, if knotty takes more then one drop to go though
Pic 7 getting fuel out of “hotbox”
Pic 8 fueling up Caddy

This is more detailed on Wood Powered Caddy thread

Hi guys, I am new on hear and was apprehensive that everybody was rolling in dough when I saw some of the gasifiers. Then I saw Waynes chunker and was really impressed with the way he took old junk and converted it into something awesome and useful. Some people think recycling means turning in your beer cans, but it can be so much more, very good Wayne a little imagination goes a long way on the farm.