# Wood Chunkers



## tom in maine (Feb 5, 2010)

I am wondering if anyone has seen any info on either wood chunkers that make fist sized chunks out of tree length wood or chippers like the Kopo from the early '80's that made hand sized
wood chips.
These would seem to be a very effective way to process firewood that eliminated bucking and splitting while allowing the processor to hand bulk material a little like pellets.
The pieces are big enough that they can dry similar to stickwood.

Just curious if anyone has seen equipment that does this.
I should've paid more attention at the Bangor Logger's show, but I was too busy looking at boilers to pay much attention to the big toys.

Might burn too fast for gasifier boilers, but I know it would be a perfect fuel for our installation.


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## sdrobertson (Feb 6, 2010)

I have no information on this but I purchased a 4 full cord load of Oak cut-offs last winter.  The pieces were mostly end pieces off log beams around 5" by 8" by 8"'s.  They burn really well once I got some dried but I had a hell of a time figuring out how to dry them.  No way to stack them and couldn't get enough air flow when piled.  I ended up putting some in 4 ft square parts containers that have wire sides so I could get some airflow through them but I had to rotate them quite abit.  It was a handling nightmare and even though they were really cheap, I'm not sure I'll purchase any more.  If there was a good way to dry them, I'd like to hear about it.


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## flyingcow (Feb 7, 2010)

Tom, 
   Heard you mentioning this on the radio show, but i had to leave the vehicle. Any responses?


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## tom in maine (Feb 7, 2010)

None yet.


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## flyingcow (Feb 7, 2010)

I googled it and there were some references, a little info


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## pybyr (Feb 7, 2010)

I'm interested in following this; from observations to date, I think such chunks would do very well in my Econoburn.  Re: Sdrobertson's experience about the oak cut-offs requiring a lot of time and effort to dry, in my experience, that's largely just the way oak is.  There's not a lot of oak near me, and previously, when I could find some, I always was glad, due to its weight/ BTU content-- but I've noticed that oak still hisses moisture more at 2-3 years seasoning than maple does after only 6 months.  Something about oak's grain structure must really retain water.


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## sgschwend (Feb 7, 2010)

Red Oak breaths white oak does not, I would think the white oak would season slowly (there are many kinds of oak).

I only found very old and obsolete references to chunkers.  Perhaps they used a hammer mill  on scrap stumps.  Then sorted the large parts out as chunks.

A hammer mill is not a chipper, it has a rotating hammer head that pounds the input into a mulch.  A chipper has a rotary planer that cuts the input into chips, some home owner models also have flailers that break up the small stuff.  Hammer heads are less sensitive to rocks, metal and none wood parts.


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## leaddog (Feb 8, 2010)

I bought an old corn chopper pto driven and took off the corn head and made a chipper out of it and chipped brush that was dry. It would chip 3in stuff ok but it was smaller chips than chunkers. I've thought about taking half of the knifes off to get bigger pieces. I thought it would be nice to get 3 to 6in pieces as they wouldn't pack and give better air flow and could still be handled like chips. On some of the larger chippers it might be able to remove some of the knifes and make bigger chips but I don't know. Has anyone tried?????????? I do think that it could be a very good fuel and could use more of the tree and trees that aren't now being used. Hope someone has more ideas on this.
leaddog


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## Duetech (Feb 8, 2010)

sdrobertson said:
			
		

> I have no information on this but I purchased a 4 full cord load of Oak cut-offs last winter.  The pieces were mostly end pieces off log beams around 5" by 8" by 8"'s.  They burn really well once I got some dried but I had a hell of a time figuring out how to dry them.  No way to stack them and couldn't get enough air flow when piled.  I ended up putting some in 4 ft square parts containers that have wire sides so I could get some airflow through them but I had to rotate them quite abit.  It was a handling nightmare and even though they were really cheap, I'm not sure I'll purchase any more.  If there was a good way to dry them, I'd like to hear about it.



Since I heat dhw with my boiler in the summer I made plans to build a drier for my splits. That's as far as I got as work and home improvement took precedent.  Simple overview was a cabinet built to hold about 2/3 of a face cord (which is 48" x 16" x 96" or 1/3 cord in my area/racking for piece separation would reduce the actual volume) using an automoblie heater core for the heating element. Plumb it from the boiler return line. Obviously proper venting would be needed for air circulation and a difuser to spread the heat evenly throughout the bottom. "Gravity" heat. An added bonus for me is the location of my boiler is in an unheated out building and in the winter the "drier" would become a firewood pre-heater. 
Seems something like this drier would work ideally for fist sized chunks by reducing the handling or eliminating the nightmare you mentioned. Some have mentioned that air flow is needed and admittedly this has a slow air flow but a cabinet heat of around 140 f (+) will force the wood to release its moisture more readily.
 Over all though I think I would prefer to handle splits as I have been getting my firewood custom cut/split and delivered for about equal to my time and effort. If I could get the chunks delivered at a cheap enough price I would go that route though. For non summer dhw set ups I think solar would be a great application for a drier.


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## Gooserider (Feb 12, 2010)

I'm going to move this over to the Wood Shed, as it seems like a more appropriate area, and might promote better discussion....  

I will say that I'd love to see something that would chop up brush / branches that are to small to turn into cordwood (and when I'm cutting a tree off my property, that includes anything down to 1-2" diameter) as it really bugs me that I don't really have a good way to use all the brush left over after taking down a tree.  If I could get it chopped up into 2-3" long chunks, that would make the branching of the small stuff non relevant, and be something that could presumably be stacked in a bin of some sort to dry fairly quickly, and be handled in trash cans or equivalent...  Probably wouldn't be good for long burns, but would be great to start fires, or those times when a lot of heat is needed quickly...

Gooserider


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## bogydave (Feb 12, 2010)

Yea Goose,
Every-time I burn a brush pile, I think how much heat energy is being wasted. If I could store that heat, Wow, weeks worth of it.
I cut limbs 2" to 1" or so & use them for cookout fires, sit around the campfire & drindk beer fires & evening smores fires. 
I guess I could even use it for shoulder wood but it would burn up pretty fast.
It is BTUs for sure.


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## Duetech (Feb 12, 2010)

I use a shortened "squared" split that I can lay cross grained to the  movement of the splitter head as a backstop of my splitter. That way the splitter wedge head can be used as a chopper for small stuff up to about 1.5". The wedge needs to be sharpened to cut better or it will shoot stuff out. The drier the branches the faster it will shoot out but greener branches make a sharp wedge head a must.


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## sgschwend (Feb 12, 2010)

I talked to my brother who runs a tree service.  He tells me their might be two ways to make chunks with machines that are readily available.  
One would be to use a harvester which has a crosscutting knife (not a saw) and parts off 3-4" chunks, stack and dry and assume they will break apart due to the stresses.  This machine can cut up to a 15" diameter log.

The other is to take a hammer mill and remove the smaller screens so that the material can be coarsely produced.


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## tom in maine (Feb 12, 2010)

There is some stuff that USDA did on this. The hardware has been described and it is simple.
Whether or not it stands up to the abuse that it is put through is another story.

There was also work done at the University of Maine. I think the guy who did it has passed away (his work was
done in the '70's).

I will try to post the USDA stuff. It is an interesting read.
There is also a guy out west who made one for feeding a gasifier that ran his tractor.


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## sgschwend (Feb 20, 2010)

Take a look at www.chomper.com  this is a firewood processor that shears the logs instead of cross cutting.

I am building a wood processor for my sawmill slabs and will be attempting the same shear process.  In my case the slab have a sawn flat bottom that can be pushed along a roller top table.  The slab will extend through a H frame style press that will have a shear blade driven by a hydraulic cylinder.  The trick is to develop enough pressure (large cylinder) and fairly good speed using a very large hydraulic pump.

I do not plan on short shearing, but don't see that as an excluded idea.


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## gyrfalcon (Feb 20, 2010)

sgschwend said:
			
		

> Red Oak breaths white oak does not, I would think the white oak would season slowly (there are many kinds of oak).



A-ha!  What makes you say this?  I got a small amount of red oak in late this summer, and after splitting it down quite far and stacking it criss-cross, it burned quite nicely by January-- still hissed a bit, but less than the rock maple I gave the same treatment to.  I have zero experience with white oak so no basis for comparison, but I was surprised at the red oak after all the moaning and groaning I've read here from experienced folks about how long "oak" takes to season.

So what is it that's different about the structure of red and white oak?


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## sgschwend (Feb 20, 2010)

Red Oak has capillaries that run the length of the tree.  You can take an 6 foot length of red oak and make bubbles in a bucket, just like a straw.   That is why I said it breaths, white oak does not have capillaries and so it can hold its moisture much longer.

There are studies done to measure the time necessary for water to transport through wood.  In softwood it takes about 60 days for the moisture to travel 1/2".  So if you had small splits you might have them ready quite quickly.

I could look up red oak for you to see what the transport speed is, would that be helpful?

Found http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr121.pdf 
If you lived in Burlington VT, August drying time for 1" thick boards to 30 percent MC is 35 days. by September 1, drying time is up to 48 days.

For 1.5" thick it goes up to 100 days, or August to November.


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## gyrfalcon (Feb 20, 2010)

sgschwend said:
			
		

> Red Oak has capillaries that run the length of the tree.  You can take an 6 foot length of red oak and make bubbles in a bucket, just like a straw.   That is why I said it breaths, white oak does not have capillaries and so it can hold its moisture much longer.
> 
> There are studies done to measure the time necessary for water to transport through wood.  In softwood it takes about 60 days for the moisture to travel 1/2".  So if you had small splits you might have them ready quite quickly.
> 
> ...



Wow, great chart, fascinating information.  Thank you very much.  It's so good to get actual data, since our anecdotal experiences are so very variable.


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## tiber (Feb 20, 2010)

sgschwend said:
			
		

> Take a look at www.chomper.com  this is a firewood processor that shears the logs instead of cross cutting.



http://www.chomper.NET

I don't have $17k.


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## leaddog (Feb 21, 2010)

tiber said:
			
		

> sgschwend said:
> 
> 
> 
> ...



I emailed them for more info. They have a pto unit that is only $14,500. I asked about a unit with out the pump and tank as it could be run with a skidsteer high flo. Might be they could sell to rental places and such. I wonder how it would run on oak, elm and hedge. It sure would work good on truck loads of logs if it could cut the tough stuff. I'll post if I get any info
leaddog


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