JO´s Rebak Chunker

Finally found some time finishing my rebak chunker. Wouldn´t call her gorgeous but she´s made almost only out of junk I had lying around. The electric motor had been sitting in my neighbour´s barn for 30+ years. He was on his way dumping it. One mans trash…

It seems to handle up to 2" limbs. Cunks get 2,5" long. A little longer when thinner.

As soon as I get my slabs, stripes and “stickers” home from my milling site I´ll do a vid of it running. Might take a while though. It´s been pouring down for weeks and only a few degrees above freezing. Have had a few hours of sun - I was at work.


Nice looking unit Jan. Looks like it is working good too. We would like to see a video for sure. I guess your motors are rated in kw, but I’m wondering what it takes to bite those limbs?? I hate to ask you to unbolt the guards, but am curious what’s “under the hood”? Good job.


Very nice Jan. I too would like to to see the gears. What HP and rpms does it run at?

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Good morning,

Carl, Bill - it´s a 6 pole motor. Gives only 950 rpm at 50HZ, which is good.
It´s old and actually rated 2hp at 500V (industrial voltage - it´s probably from nearby papermill). Since my domestic is 400V I´ll get only 1,6hp out of it, which is not so good, but still sufficient. On the other hand gearing ratio decides biting force.

Pullies: 1:2,4 ratio (100mm:240mm). Big pully is from an old lawn mower tractor.

Chain drive: 1:4 ratio (11:44 teeth). Double bicycle chains. Gears from two slaughtered bicycles. They are worn out, but to this application I had the opportunity to turn them around (brand new on that side) :smile:
Maths says end result is close to 100 rpm = 6,6 snaps/s. Slower than most youtube rebaks, but fast enough.

Cutting shaft gears: I don´t have any machining equipment. These gears are commercial shop made. One of their customers rejected them and they were occupying shelf space. They are sturdy hardened steel. I couldn´t get hold of a smaller one to drive them. That´s why I went the chain drive route.
Reason for gearing inside frame is that the hardened gears came with bearings pressed in to them, which means that my 20mm bolt shafts are at a stand still. Cutting blades are 6mm ss plates bolted to 50mm square pipes. I pressed bearings into the pipes.

EDIT: Wayne should have one of these. Bites look like beavers did it. I understand they are one of his favorite animals. :smile:


JO; You are becoming one of my favorite “posters”. Your original engineering is amazing. I realize that the basic idea of the saw mill and the rebak are not original, but you "get her done’ attitude of using materials available is amazing. What dimension on your rebak determines the length of the chunks? And also what dimension determines the max diameter you can chunk. Thanks for the great pictures and description.TomC

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Thanks for the pictures Jan. I imagine at 100 rpm those chunks will fly out of there.
Is the single belt pulley sufficient or will it slip if too big of piece goes through there?
I really appreciate your construction on this. A video would be nice to see it in operation.
Thanks again.

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Looking good Jan :wink:

I have a beaver dam that needs busting out right now but hate to wade through the snakes to tackle it :grimacing:


WOW great stuff Jan. I love it when odd parts come together to make a very useful function.

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I´ve learned this is the time to admit my helmet size will have to be adjusted at work tomorrow. I´ve already put my head out the window to get a cold shower. Thank you all for nice comments.

Length of chunks will only be determined by number of cutting blades and dia of gears/blades. Varies a little with limb dia though since the limb travels a bit further until next couple of blades bites when thinner. Max limb dia is determined by blade depth and power or gear ratio.

Single belt is more than sufficient for my 1,6hp. The belt doesn´t slip. The motor stalls. It seems to handle up to 2" limbs. I don´t think a fly wheel will help any since the motor won´t have time to catch up between cuts.

Carl and Wayne,
Carl wrote: “I love it when odd parts come together to make a very useful function.”
I think that´s what the beavers are thinking when they build their dam. :smile:


Working OT and rain. When finally a day off and sunshine, wife asks me join her go shopping ??? Told her I had to relax:

My “fancy” bucket guard is no good.
I know you prefer a closer look at her private parts anyway - so here you go:

She seams to stall when biting more than one chunk at the time. Chunks sometimes get stuck between the blade bolts and go for another round. I think I will change the bolts out - do some countersinking.


That thing is awesome!!!


I’m with Matt, that thing is awesome! Do you think if the motor was a little stronger it would keep it from stopping? That has to be the fastest chunker on this site. Great job Jan!


I have to echo the group, “that thing just eats up the wood”! Nice job, JO.

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very cool. Those fuel chunks look delicious. perfect size and shape. You know something is wrong when you see chunked up roundies and call them delicious!


great looking machine

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It looks like you have a “cord wood” house behind of you.

The Rebak chunker really does make nice chunks. Can I order about a 1000 pounds shipped to my door.TomC


Hello Jan

Nice , I like it !

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Thank you all for your nice comments.

Bill: Yes, it could use a bit more power, but I think `ll start with:
“She seams to stall when biting more than one chunk at the time. Chunks sometimes get stuck between the blade bolts and go for another round. I think I will change the bolts out - do some countersinking.” (how do I make those nice marked quotes?)

Joseph: My wife would agree :wink:

Tom: That wall will get naked fast (September - Christmas) and your order is confirmed - address please (shipping will be added to your bill)


Select the text and click the grey “quote reply” button.


Nice machine. I think rebaks are ideal for processing branchwood and very small logs. I don’t know anyone in my area who doesn’t burn piles of brush as a waste because of potential processing time. These machine make the smaller wood a viable option for anyone.

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