YEA Dustin
That’s what I’m talking about have a large base plate or something to keep it from flopping around or something to drive up on to elevate the wheels, like a dyno could drive the drum?
Yeah I think what Dustin is doing will work and will be good example to follow. The system I want to design is something Im considering adding to our product line. So everything I use will need to be new and readily available to build over and over. I will do what can to keep it inexpensive but I want to be able to use a 5 hp engine or most likely a 10 hp to run on wood gas. Then I will also make it available for those that want to build there own versions.
Hi MattR if you want to pursue this idea think on your primary hub something with as big of opposing tapered roller bearing as possible. The side thrust forces needed to restain are in the range of many tons. This will easily bend a 2" straight shaft. Destroyed a lot of shearing ideas with my 34 ton woodsplitter working up the the infamous Chevy V-8 powered spiral shear “DeathChipper” project.
Doing it this the rotating side shear way I’d suggest a double hub arraignment. Cutter head 6 to 1 industrial drive chained to the first parallel hub. That hub then 6 to 1 down by belt(s) drive or IC engine friction wheel drive an actual primary hub mounted trailer wheel and tire (cheapest, best flywheel). This double up 6 to 1 would drop an easy woodgassed 2000 engine RPM down to a cutting head 55 RPM. For safety you do need to have either slippable belt(s) or the friction wheel in line somewhere. Find Jussie’s video for how to do the wheel tire and friction drive set up. Those commercial multi-spring slip clutches cost much to purchase and then repair. They sacrifice themselves to save equipment - once, twice, thirce, then it will be burntout toast. For the amount of stall loading protection for the actual heavy knotty woods I use only hydraulic “slippage” is affordable to maintain. Learned. Destroyed too much tractor driven farm equipment.
After reviewing the Rojek, ROBAK opposing clipper videos here is an easy idea to try that I do not know why it never ocurred to me until now:
Take a standard engine driven hydralic ram woodsplitter and make a drop-in opposing shear to fit over the flat foot. Only using a 6 inch stroke I could cycle my wood splitter for ~10-12 “Snips” a minute. Think of it like big powered fingernail clippers. Snip. Snip.
I hope Dave Orrell read this for his O frame shear he was building. This will cut the shearing forces need over in half.
Regards
Steve Unruh
When in doubt design it stout
After looking at the WK chunker in action it looks like it is running at 75~ rpm. Assuming the tractor is at low speed/ hp I would estimate that the circular rim with the progressive wedge is producing 8,000 -10,000 in/lb of axle torque. Divide that by the rim radius and you would have the torque applied at the wedge. The thrust load and axial load on that truck frame is a walk in the park and would prob last forever because it is operating at a service factor of 5 or better. I agree with Steve in that what ever is built to clip wood will have to be built stout. Use type E bearings which are designed for thrust loads. It wouldn’t surprise me if the the chunker produces several tons of force. My 2c worth.
Wes
Hi Wes,
I always thought the saying goes: “When in doubt, drink a stout!”
Best regards,
Sam
Hi All
Just finished loading up a bunch is woodstoving pictures and added these at my 34 ton woodsplitter.
You can see the 1 7/8" - 47mm thick steel foot plate has now been bent from the force of shearing Doug Fir knots straight accross. Next pictures show the 4" - 100mm knots. This stalls the two speed hydraulic system into a crawl at full 10.5 hp engine scream.
The straight on sharpened pusher edge has to compress the right angled wood fibers around itself and streach them taunt until it can cut through them progressively compressed layer by layer.
This takes all of the 68,000 pounds of pressure to do this brute straight on. (Sorry metric guys I do not do metric forces well)
A rotating shearing edge might reduce the system side compressive force needed by 3/4. That will still be 17,000 pounds = 8.5 tons of side force applied to have to oppose. Easy for a HD bus or truck with full floating opposed tapered bearing axle ends. Anything less . . . ? ? ?
A conventional saw blade tooth actually scoops and lifts up a short band/stack of woodfibers streching them and then cuts/tears them loose. Very very little compresive densifing of the fibers at all - mostly pulling and streaching. Even an old style back and forth crosscut saw blade only has the left and right cutter teeth compressing a short stack of wood fibers in the cutting actions and then has the raker teeth center tear loose and sweep out the freed up cut wood chunks and strands.
One reason sawing takes so much less applied power and force.
The other major reason is a good sawing blade or saw chain has the teeth cutter tips angle out to clear a wider “kerf” than it’s body and so has NO or little side dragging.
Shear cutting straight on or with even with a tangential motion accross the fibers has to be forcing a wedge shape cutter into the side woods to get the actual sharp cutting edge in, compressing densifing even more wood fibers than just at the front edge. Compressing/crushing wood fibers and cells takes a lot of force and energy. This is the whole principal behind modern energy absorbing structures like car bumpers, composite tank armor and bullet proof vests.
Ma’ Nature knew this all along. Old wooden stucture builders knew this well too. We metals moderns are just having to relearn forgotton/abandoned knowleges.
Regards
Steve Unruh
that bent foot plate is the reason i have always made log splitters with a flat plate on the ram and the splitting plate as the fixed end…you can make the blade deeper giving it more strength without reducing the length of wood you can fit in the splitter…
a good splitter design should NOT be capable of bending any part of itself irrespective of what its being used to split…i alway work out what size “i beam” and steel size/thickness i need for the load then double them
Hey CallumH
You are correct. I have used both styles of splitters. Both ways have there pro’s and cons. Fixed splitting plate style the plate can be much thinner greatly reducing the splitting force needed. On the other hand I’ve had to hand beat loose, or worse, chainsaw cut loose stuck knarely compressed twisted grained butt wood chunks that these machines failed to split all of the way through. Splitting wedge on the the ram and then it is easy to set up stripping Rams horns to strip off stuck chunks on hydraulic ram retact. And as an old man I can stand in one spot and roll, turn and fine split down large up to 40 kg chunks without having to chase down out of arms length receiving bed halves. Also my current splitter can single pin tip up for vertical use to roll-on breaking down of the really big stuff. the foot bent because I was accross the grain forcing up to 6" 150mm knots - MY BAD. I along the grain center halve these now and save the funny shapes for the bigger stove.
On the woodgas slicing chunking topic:
New member Vesa Makinen just put up a topic with links to Finnish woodgas vehicles.
On the ekoautoilijat.fi link are 3 different “pilkekone” = chopping machine picture sets.
Two by Jussi Aystom of his heavy transit bus axle based 3kw electric motor driven system. Neat conveyor chute off loader on his system.
Another by Paavo Saaskilahden built around what looks to be a much lighter, smaller 3/4 ton truck rear axle.
Both of these have screw wedge splitters on the opposing axle ends.
http://driveonwood.com/forum/967
Also some AG tractor woodgassed converted picture sets there CallumH.
Regards
Steve Unruh
Hello everyone!
It’s good to hear that kind words about us, people from central Europe.
If you are interested in complete CAD drawings for the wood chipper, let me know via PM and I’ll upload them on a server.
In Poland we usually use disc chippers. Chippers with 2 shaft are commonly used in Czech Republic.
They call them drtic vetvi or stepkovac.
Now I’m gathering material for such chipper, but the goal is to find as much as I can o a scrapyard.
Chipper from my plans (ones that i can upload) will cost circa 800$ including material and machining.
Plans are free of charge, let’s say they are open source.
Best regards
A. Stelmach
p.s.
People in Czech make 3 kids of chippers:
- round shafts:
- triangle shafts
- square shafts
Ones with square shafts are easy to make, round shaft need a lot of machining and are expensive.
http://jamclasses.drbanjo.com/static/dimages/3kat.jpeg
i’d love to see your plans
Hello Aleksander,
I am really interested in this chopper design. I would greatly appreciate any plans to start with.
Thanks and Happy Easter (Wielkanoc)!
Sam
I love this wood chunker, but do not have the smarts to design a working one. I too would like to see a set of plans to build this meself. If I have the plans I could build one.
Hi everyone, time to add my two cents reference axle chunkers. Steve U. is correct that these chunkers use extreme forces to do the job. Using anything but a heavy truck axle in my opinion just won’t work. I have built http://www.youtube.com/watch?v=WlWMter1y04a W.K. axle chunker driven by a rubber vehicle tire on the pinion driven by a 2" pipe to spin the wheel from a 13 H.P. Honda engine. Tried wheels like w.k. that came with axle and because I cut oak I kept bending wheel. Finally made cutting wheel from 12’ x 3/8’ thick steel pipe(no more bending). I added 150 # of weight to the actual cutting wheel and later after all videos added solid rubber filler to drive tire that made it weigh 180# to act as a flywheel. I actually added a 1/4’ steel cable above the unit to counter the bending torque of the axle under pressure of the wood being chunked. You can hear and see the brute force being applied to the axle. I actually worry about the possibility of this heavy axle breaking. It is a two speed International axle used on low gear only.
Good Morning Danny,
Yes you are right about chunking the wood. It takes a lot of brute force and heavy flywheel action.
Danny, great job on the chunker! You’ve got some serious flywheel weight going there…
One difference I noticed between your unit and Waynes, he’s got the spiders welded solid, while you’re holding one wheel stationary. So his input is spinning twice as fast as yours. You could double your torque/halve your output speed by going the other route.
Another thing is, Wayne will usually chunk green stuff, whereas that big piece you were using was pretty dry (I think). If you get a chance try a 2-3" fresh green branch and see if it’s any less shock on the unit when it cuts.
Hi Chris; That piece was green, just hacked it down for test.(now on some folks s t list). Are you sure about the torque/speed thing before I attempt it. Thank you for imput.You too Wayne. Dan
Not sure the results are useable but it is impressive.
Hello Danny,
What is your approximate speed of the input shaft ( drive shaft ) ?
I like to run my input shaft 400-500 rpm and end up with good chunking speed
If your spider gears are allowed to function by locking one wheel and the other turning you are losing half your torque .
Hi wayne; Not sure of the r.p.m.'s of the pinion. All I know is thst the 13 h.p. Honda engine is running at idle now that I have made the drive wheel/tire weight 180lbs… The wheel weight was added after my last video. Having trouble wrapping my head around how welding the spiders will double the torque. I will trust yours and Chris’s experience on this one as I don’t have experience on axles to any great extent. Thank you for your time to help out. Dan
Good Morning Danny,
Hold on just a little before you start any welding on my account. I want to make sure I’m not leading anyone down the wrong path.
I have watched some of your videos but probably not all and I’m not sure I understand your setup.
On the wheel or axle opposite the chunker are you having to lock it still to cause the cunker to operate?
There are many types of differentials and I don’t know what you are using except you said is is a two speed.
Many have the capability to lock the spider gears with just the moving of a lever and some have a limited slip ( farm tractors , log skidders etc)
Just a broad and general statement is if you are having to lock one axle to cause the other to rotate , the speed is doubled but the force is reduced to half.
When I first built my chunker I first tried to use the opposing brake to lock the axle. To work correctly I needed a slower rpm input but twice the torque . That meant a big tractor running at slow rpm.
The chunker is much more efficient working with a very little motor at higher rpm’s letting the flywheel action do the work.