Harbor Freight Chipper! (Open Source)

Ok went out and spent the money on this thing. Im glad I did!!

I think Im going to endorse this chipper as a fuel grade processor. I just got this and have more to learn yet, but I have ran the fuel it processed and it worked!! Not only that the fuel was green. Im learning that how you feed into it will determine chunk sizes. The faster you feed the heavier the chips. I have a ton of branches to run in this so I will have plenty to learn on. Again I am very impressed with the Predator engine, this has the 212 CC on it and it runs beautifully.I did have to screen the fuel, the branches have a lot of small limbs that the chipper just spits out. These small twigs are long and for sure would create some issues.

As is stock I believe this machine can make good fuel for our smaller scale systems. I also think we might be able to mod this thing to make it even better. Adding a flywheel for instance and upgrading the engine to the 13 horse. Even at the added cost of the 13 hp engine you are still getting a deal and then you get the 212 engine to do what you want with maybe a wood gas gocart or something lol.

I havent had much time to take pics or anything, been pretty busy with that CNC machine. But now that I have this machine I feel pretty liberated. Once I have the funds to get the splitter and a little larger generator to run that chain saw on woodgas. I will have full capability to fully process all fuels from 100% wood gas. Im going to have to start a topic on the chain saws too. The Poulan is indeed a good saw; however, you can get better saws. I have been getting into a lot of processing for the wood stoves as we are out of wood. So Ive been going out back and processing what we have on our 5 acre lot. We have quite a bit already cut down trees and Ive been doing all the processing with the electric powered by my little green genny. I actually like that electric a lot better then a gas saw. Its lighter has plenty of power, need messing around with two stroke oil, and I think its probably more efficient as well. Ive ran the green generator for at least a week one tank to run the saw. There is no way a gas saw could do that, its funny as when you run this on a generator its a lot like running a gas saw. The generator reacts to the load almost the same exact way. My only gripe is being tethered by the cord, but its not to big an issue.

As soon as I get some time Ill at least get some pictures going on this. I guess Im going to learn to compost now that I have this too :fire:


I’m excited to see a picture and know what model of chipper you have. Maybe also a picture of the fuel it makes in your hand?


I think he has this one:

Quickly reduce piles of leaves and small branches to useful mulch with this powerful 6.5 HP gas powered chipper shredder.

  • Chips limbs up to 3 in. diameter
  • Heavy duty steel leaf hopper
  • 20:1 waste reduction ratio
  • Includes garden waste bag
  • Shredding plate with four chipper blades
  • Smooth-rolling 12 in. wheels
  • Low oil shutdown
  • An additional lift-gate charge may apply.


I am pleasantly surprised that you can run your gasifiers on the chips that come from that machine. Have you chipped and sorted enough chips to get some “numbers” on the percentage of usable chips from a typical chipping session? A friend has a chipper of that size and the chips we got from it were really small.
Look at the wood chip measuring gauge here:
The largest chips we got would go through the 2 and 3 mm slots.
There are a couple of pix farther down that page that show small piles of chips that I measured.

I don’t have an Imbert style gasifier, but I thought that most of them (and the Wayne Keith type) use wood blocks. I don’t use chips that fall through a 1/2" X 1/2" screen in my stratified downdraft system. But I can’t use blocks, either…
What are the smallest size chips that work well for you? The largest?

Pete Stanaitis


Hey Pete, this is exactly why I put this in its own thread. I prolly should add “open source” to the title as I think we can make this machine better. This will come later.

Very cool on the measuring, I have cell phone internet and its a bit slow. Ill look at this in more detail soon, but very cool concept of measuring chips!!

The chips I first produced were a bit small, I was reservedly feeding the machine during break in but later just started shoving it in haha!!!

If your feed stock have a lot of little branches indeed you have to screen the fuel. I was getting a lot of long twigs mixed in and those need to be taken out.

Chip sizes vary a bit, I was getting small 1/4" size on up to 1" size chips. I think once I learn to feed it more consistently I can get it to make good large size chips. We have typically ran Cedar chips that we bought and this has been from the very beginning. Size of these chips range from 1 x 1 x 1/4" thick. Now the fuel this chipper is making is a bit smaller; however, I think the density of the chips is comparable to the cedar and because this fuel is slightly smaller physically; density pr hopper load is more than the cedar.

What I was hoping for with this chipper is that it made a thick chip and that it didn’t make mulch. It does just that, even though the length and height is not very big, the thickness is there. I couldn’t find one video or one picture or any info the chips this produced. I went off one video I saw that showed the chips bounce of the ground. I knew form watching that video those chips had to have some density for them to do that. So that is why I gave it a try.

Ok now running chips vs chunks vs pellets. Size does matter and you can not change physics. This is just my take on this and based on my experience; Ive built just about every size machine in diameter up to 18". The smaller the machine the less tolerant it is we know that one. If the machine is 10" diameter or less, this is basically a pellet machine. 8-10" you may be able to run chips but will need a lot of intervention and run times will be very short. Machines 12" to 14" I think this fuel will work fine and maybe the most appropriate to run. It will give a good hopper wieght density and flow well. Once we get over 14" then you have a lot more tolerance, and can run chunked fuels, larger sized chips, and I think this fuel will work just as well. The Italian machine ran on olive branch chips, these chips are comparable to what the HF chipper is producing.so Im hoping this fuel will work in our larger unit as well. This will make the auger feed system work a bit more efficient as well.

It sounds like you are a bit ahead of me in this, right now Im very optimistic maybe. :slight_smile:

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I’m interested here because I have a decent chipper. It gobbles up 3" branches with ease and I want to be able to gasify them.
This is the size chips I’m getting which seems adequate for a smaller gasifier. It worked in my first unit.
In my best ‘Donald voice’, “My hands are huuuge”. Sorry, I had to. :slight_smile:


Those are comparable to the HF machine. Yeah those are what we are looking for!!


I could run those all day long in my systems… 6 inch hearth


On the heaver duty electic chain saws there are the three differnt Stihl brand models.
Ihave the middle duty model. Works great ONCE I changed over from the narrow kerf bar and chain to a standard duty 3/8" chain and matching bar. We were winter inside of woodshed ripping down/accross split out knot chunks to fit into the woodstoves. The hard knots would break off the narrow kerf PICO chain teeth. We put so many hours on this saw over the years I’ve had to repace the motor brushes once already.
The electric chain saws start up with full torque and have no IC engine piston/gasses softening “give” to the chains.

Probably the heaviest duty AC electric saws out their is the highest line Husavarna. This one has a gear drive. All other are in-line direct drive.

These HD commercial grade electric saws cost as much as a commercial grade gasoline chainsaw.

Steve Unruh


Thanks Steve!

I’ve been eyeballing this Makita, but now I’ll go take a long look at both the Stihl and Husqvarna models.

Husqvarna seems to only have battery powered electric models now. I’ll look around for an older corded version.

Stihl has two good looking models, a 18"-20" version and a 12"-16" version


I have a cheap craftsman 3 hp 16" electric that I bought used just to see how I liked electrics (which I really do!) and I was waiting for it to break so I could buy a good one like you are talking about, but that thing just won’t break. I cut down and cut up 2 ft trees with it several times and though it is not as fast as my gas saw it gets the job done in peace and quiet. When I look at the price they want for the high end electrics I think I could buy several of these.


The cheap craftmans that I had would last for 10 cords of hardwood constantly.

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Yup exactly what Steve said. the electrics have instant torque. Ive always considered the electrics to be toys, not anymore. As soon as I break the Poulan Ill be getting a Still or Husky :slight_smile: The Poulan has been discontinued and its like the HF saw, once its broke; its broke no replacement parts to fix it. There is a planetary gear inside that drives it and it is plastic.

Yesterday, I went out and played around with the chipper. I tried a lot different methods chipping and shredding with it. You can see in the photos the branches Im working with have a lot of small branches. If you leave them, you have to screen these out later. as the machine will not fully process them. You will get all these long twigs mixed in with the fuel. I ran a batch with them left on and after that I pruned them all off. I think its better to just prune first its less work later and you get better chips with less dust in the product. So you got to de-limb your limbs!!! I then process those left overs in the chipper side of the machine and then rerun them in the mulcher feature and get a nice mulch from them. My chips vary a lot in size’ however, the branches I ran also varied a lot; smaller branches make small chips vise versa with larger branches. The larger 2- 3" branches do make a pretty heavy chip. This is why I want to get the splitter I want to try and split wood small enough to fit and then we should get a nice consistent large chip from this machine with no screening required. So Ive already started a compost pile, does anyone know if there is a thread here on composting. If so point me in the right direction, or maybe I will start one and hopefully Troy Martz will chime in on that one :slight_smile:

So another portion of this is going to be drying the fuel. I ran another batch in the gasifier and this time it didn’t go so well. I don’t believe sizing is the issue, the fuel is green and I think once its dried it will work fine. Not interested in extensive screening processes, The fuel that was pre pruned I would not even bother to screen in a gravity feed hopper. Our auger system on the other hand will need at least one screening to prevent any larger jamming pieces from getting in there. The first run I did was in blower mode and it also had a pre existing char bed from other fuels. Yesterday when I ran I tried running in engine mode and the char bed was well converted. The combustion zone kept voiding out and I made me some tars haha. So Im going to build some sort of dryer, Im thinking of building some sort of rocket stove or a barrel stove for the heating part and then a tumbler barrel in the exhaust stream.


Compost: Locate Pile (area and proximity to house & garden), measure ingredients (C:N ratio by dry weight 25:1 – 40:1), PH (add ashes if too acidic), shred ingredients (increase reactive surface), inoculate (add dirt or compost for microbes), moisture (feels like squeezed out sponge 40-60%), amass (minimum optimum volume 4’X4’X4’), aerate (vents through and under or turn when reaction temp drops)


Not here, but over there, there’s a whole sub-forum for composting: http://www.permies.com/forums/f-72/composting

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Sounds good Matt
Keep up the hard work
And thank you for all the input
Us new gassers espacially, need to hear from experienced
Knowedgable men
Thank you


Will the Honda generator run that saw?

Marvin if you were asking me if my wife’s Honda EU2000I would power my Stihl electric chainsaw? Yes. But under a long sawing power loading the Honda will overload indicate and turn off it’s AC output.
My newer, larger Yamaha EF2800i will power the Stihl corded saw continuously.

I’ve passed on the newer cordless saws. Some of these are even up to 42 vdc now. They get bulky with the battery pacs. I’ve hard worked used up 12vdc and 14.5 vdc cordless batt pacs. Not cheap to replace.
Laptop batts have ran me $80-100. to replace.


Wow, I’ve been screaming chips for months now,…glad it’s finally catching on!

Processing fuel into ANY other size is a monumental WASTE of time, it’s chips or bust - if you have to spend hours processing wood into fuel, you might as well spend them at work with an air conditioner and radio and just buy gas.

Chips keep driving on wood (or generating on wood) almost free because processing doesn’t consume 100% of your free time. Never mind that almost every tree outfit around will happily GIVE you truck loads of them for free.

Way to go Matt, I hope this continues to yield positive results for you. I’m working on a design for a wood chip drying oven to get them down to a moisture level that will permit storage in a silo so they can be easily accessed and used any time of year.

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You know that’s not true. Watch the hyperbole…

There are good reasons to use chunked fuel. Pound for pound, it takes less energy and time to cut up chunks than chips. Larger gasifiers require chunks, chips only work up to a certain size.

Bring your chipper to Argos, and I’ll bring my chunker. We’ll have a race cutting up 300 pounds of fuel from 2-3 inch sticks. The only way to win that is by bringing a giant commercial chipper (in which case I get to bring a Rojek.)

Granted, if you get the chips already made from a tree company, that’s time you don’t have to spend gathering and cutting fuel. But if you’re going to process the fuel yourself, I think chunks are a good way to go.