firewood processor

[cascades]

Hi all, long time lurker first time poster!

I'm going to build a firewood processor, or start hoarding components for one at least. This is intending to be a very high output machine, Higher production rates take precedent over higher cost. Im in Australia, North American built processors are imported, however they struggle with our wood. Before someone suggests I buy one instead of build it, I am confident I can build a machine with better output and usability then whats available on the market, for a fifth of the price, my time included. 

General design features are .404 saw bar. Ill get a proper bent axis motor and suited pump. Row of d7/8 bottom rollers bolted in  row and chained together as in feed, teeth welded to their outsides for grip, with hydraulic motor attached to provide rotation. I have the splitting chamber already, it's an 8" cylinder. Im wanting to use air pressure for split return, clamp and saw downfeed. Use either air or electric solenoid valves for split pressure and saw on/ off. Im doing this for a couple reasons. First its easier to set up, route and use air/ electric, it should lead to quicker cycle times, and air components are a whole lot cheaper than complicated hydraulic systems. And it doesn't matter if they leak a bit! Im intending to make it all semi automated, like one touch of a button for full split cycle, hold another button for saw drop, and a lever for infeed and clamp, maybe in one joystick


Now, a few q's/ discussion.

In Australia, its a pretty regular setup to have an 066 with a 20" bar, .404. I'm a commercial wood cutter, this is what I run. I'm struggling to figure out an adequate bent axis motor size to give maximum chop times. Im sure i could put some 100hp thing on there and it will go just fine, but thats burning diesel for no reason. Im intending to cut 35"+ wood with it. Is there some formula for hp required/ wood removal rate? 

Pumps: So dedicated pump for saw. Now, there is only the split, infeed, and outfeed conveyor hydraulic functions left. Is there such thing as say a 90/10 flow divider? it would kind of annoy me to need a pump just for those two motors. Ive got a big pump for the split ram, like 60+ gpm, and would be really handy if i could just bleed off a bit of flow for a couple skimpy motors.

Does anyone have schematics for commercial units they'd be happy to share? would love to have a stickybeak how the pros go about all this!

Thanks guys, also open for any suggestions, would love a good discussion!

[stavebuyer]

I owned a processor with a .404 chain saw. It cut well when sharp and would continue to cut small diameter logs just fine even when dull but would struggle with larger knotty logs pretty quickly. If you are going to process large tough cutting material the .404 saw will be your bottleneck. 

[cascades]

Yes i've wondered about that, in a perfect world i'd put a big chop saw on it, however that would be a huge expense (contradicting myself I know). Id probably need to import a whole unit from America. Ive got a 100ft roll of semi chisel harvester chain already, kinda like the idea of using what i've got. 

Would there be much difference in sharpening intervals between a processor and a chainsaw?

[mike_belben]

You are not going to get 30" rock hard aussie wood to go through an 8 or 12way knife fast without 200+ hp, 4000psi and dual -16 hoses in and out of an 8" ram.  Not to mention all 1" plate and serious danger standing next to it.   Horrible big wood like that is much much better suited to a box knife design with a dragback and more normal sized components.

Toss the air concept out.  No one uses it and its just extra complexity for no reason.  Fast splitters are using big hp turbo diesels that can bring on gobs of extra torque in seconds... Powering not so big [aka fast] cylinders at high pressure that have very large rods to speed retraction.  They probably also use a single stage pump or design their own 2 stage pumps and dial in the unloader valve crossover so that it splits most wood in high flow and only kicks down to low flow/high pressure on bad knots as rarely as possible.  The reason a 6 or 9hp 37t splitter is so slow is because A, theyve got a 5" ram to fill and B, they kick down at like 900 psi to a 2gpm pump so that tiny motor can do it.  Its like building a briggs and stratton log truck with 90:1 gearing.

Other speed increasing options are regenerative extend and pilot operated return directly to tank instead of through the valve.  

Youre going to want to build this machine with -12 hoses minumum, preferably -16 with a 30gpm valve on the splitter ram.  Use a big motor and a multisection pump instead of flow dividers and priority valves.  

I would advance the log with the splitter ram instead of all the trouble of building rollers.  Make the top log trough a tray that is slaved to the splitter ram.  

There is nothing fast about an 8" piston with half inch ports.  To make it so youll need to tear it down and put in 1 inch ports.  If you want really fast put 4 ports and run it from 2 slaved valves.  Then youll be slammin wood and breaking welds :D

[mike_belben]

If you had access to the motor and hydraulics of a large skidsteer to cannibalize, it wouldnt be a terrible start.  Youd have two infinitely variable, bidirectional hydrostatic pumps with relief valving, charge pumps, cooling and repleneshing valves already worked out, and a fixed dispacement loader pump with 2 or 3 valves of the back all in one tandem rig.  Plus maybe even local dealer support.  Skid steers have very global supply chains compared wood splitters with one location and maybe one dealer in your country.


The hydrostatic trans sections could run your ram and your live deck while the loader valve could do any clamping, wedge adjust and saw.  


A hydrostatic pump is closed center and uses a swash to vary the piston displacement.  Maximum torque comes at minimum displacement so when retracting you just stroke for full speed.  When splitting you can ram it forward full tilt and as the motor lugs just back off the stick.  This reduces the demand for hp to achieve the same pressure at reduced flow.  It would be a very elegant wood splitter.


Chain drives, reduction gears, drive motors and axle shafts could all become part of your conveyor and live deck giblets.

[cascades]

Im not worried about the knife design, i've built big splitters before, using old dozer track pads and lots of welding. I like the air as ill be using a big diesel out of a truck, likely with a compressor already attached. 

I can save literally thousands running an air system in tandem as the more hydraulic functions the more exponentially more complex the hydraulic system gets, and more hydraulic complexity is way more cash. Granted its an additional system to fail, but I can picture in my head how to automate stuff a lot easier using air plus immense cost savings which I can spend on stuff that matters like the pumps and motors etc. i.e $30 for an air valve vs $300 for a hydraulic with the exact same function. 

Air return on the splitter is the one thing im not super sure about yet, mainly about internal leakage and how to not waste that oil. Will take big air volume too. Might scrap that part, i just liked it cos i had it all planned out how to cycle it with one button!

[cascades]

I am keeping my eye out for hydraulic components, a skid steer or ditch witch or something would be ideal. Unfortunately in Australia stuff like that is generally kept in use for its entire existence, its not the spare parts heaven of America which I envy!. 

Was thinking of trying to pick up a saw drive system out of a processor head. 

Won't have any moving wedge component, would get pulverised within about 3 cycles. 

[mike_belben]

Okay im seeing a clearer picture.  Im not too onboard with it but will try to help you sound it out anyway.  Please take this as me helping you identify the issues beforehand and not picking on you in any way.

i can say from being a truck driver and mechanic that the 2 piston bendix type air pumps on trucks are not gonna produce tons of air volume.  The clamp and saw downfeed i think will be okay... Maybe.. theyll run a bit low in small wood because of the cycle frequency...but piston retract on the splitter no way.  Just no way unless you have a 200g air tank and 3 hours for it to charge up every morning. I mean its 10 minutes at 900rpm for the 15 or 20gal on a truck to hit 90psi, and one torn 1/4" line in the dash will park a truck in 40 seconds.  Its so common to run out of air doing pullups for a tight dock or gate.. They just dont make the volume.  


Using air retract directly inside the 8" ram you may then have the issue of no lubricity to the rod bushing.  


ive built air compressors from york piston pumps and truck piston pumps.. Theyre again great as belt drive high pressure for cheap, but volume isnt there.


This is my self propelled charger, compressor jump starter, small stick welder etc.  Puts out 150 psi thru an unchecked half inch line.. Its fantastic for the big gun busting ancient junkyard lugnuts but duty cycle is naturally short.






I made a lot of air actuator stuff for ranges at smith and wesson too.  We used SMD speed controls, mufflers, valving and so forth. Clippard air switches and SMD valves.  Id look for ebay lots using those terms.  Im not against air trust me.  



You could use air to pneumatic cylinders that control the hydraulic valving for the splitter.  You could also use air cylinders to change swash plate angle for pump displacement, or to vary the pressure on poppet valves to dump fluid back to tank.  A one ended piston can only retract as fast as it can exhaust the blind end to tank so a big direct return line that bypasses the valve and filter will be the biggest speed increaser you can find.  Build a poppet that has a spring plus air applied to keep it shut while splitting, then dump that air to atmosphere to retract, while simultaneously shift your air over hydraulic spool or solenoid control valve. Please realize that 150psi of air is not gonna force that blind end fluid back to tank faster than 3000psi of hydraulic fluid.. Especially not through a -8 fitting.  Nothing is gonna retraxt faster than a poppet controlled bypass dump.  


 

That is all pretty straight forward to control by PLC for full automation if thats what u want.  The truck pump will do control quantities of air.  But sorely lacking for actual strokes.  Youd want a tow behind compressor head for that much volume.


Also keep an eye out for industrial sweepers, whether ride on or truck.  They have a lot of boutique hydraulics.   My bobcat engine had less than 400 hours from a tennant 265.  Everyone wants to cannibilize a trencher but no one sees a rusty half crushed sweeper and says thats sexy.


The fastest home made splitter i ever saw is the dibbles machine, built from a combine, on youtube.  Next up is the guy in maine with the chain drive roulette wheel wedge.  Maybe contact them direct for a vid on the specs.

[mike_belben]

Maybe it would be helpful to define fast.  I think anything faster that a 5 second extend while splitting is very fast.  Now theres a lot of bragging about fastest this and fastest that among MFRs and dont be fooled into a 5 second cycle on a 10 inch stroke where the wood is only half way through the wedge and needs the next piece to push it thru.  Short strokes are an easy way to cheat your way up the "fast" ladder.  


Anyways an 8 inch cylinder will need 36gpm to do a 14" extend stroke in 5 seconds and 52 GPM to do a 20" stroke.  

52gpm @3000psi takes all of 101 HP.  

[Hilltop366]

When I look at processor videos I tend to count out cycle times (complete cycle times from the start of a cut to the next start of a cut and taking into account the wood size) and have come to the conclusion that splitter cycle time isn't everything. Some small cheap DIY machines seem to have as good or better cycle times than large expensive ones, the biggest hangups seem to be the  clamping and the cutoff falling into the splitter crooked causing delays.

Some of the better ones seem to have less of these problems which helps good work flow as well as enough power and dedicated pumps or pump sections so they can saw at the same time as splitting so the splitter does not need to be much faster than the saw to be ready for the next block.

The expressions "Hurry slowly" or "smooth is fast" come to mind.

[mike_belben]

Yeah id say youre right about that.  Ive seen plenty of overpriced rube goldberg home made jobs that arent much better than hand cutting after you walk around the machine or lean out of the cab for every third drop that lands eye to the sky. 

 Or they got a mountain of processor and support equipment but it takes 5 friends to run wood.   If you got 5 guys who wanna hang out and drink beer just give em all wedges and sledges and save your money.

[mike_belben]

This is what i mean by slaving the feed table to the splitter.  He has low power and/or some feed rate and stroke length issues preventing it from being fast but overall i feel its a very affordable design.  Even more so if one mounted a chainsaw and manual log drag.  Would only need one valve. 

Dan's homemade wood processor - YouTube



 Halverson loader mounted processors use the same trough feeder principle.  

[moodnacreek]

Block buster does or did air return. Had an on board compressor .  An eight in stroke is alot and a 60 gallon flow, probably need that much. How much pressure?  That cylinder needs a real fat rod to get any return speed. I would love to see the multi knife splitter that will take what an 8" will do.

[OH logger]

Blockbuster does use air return on the splitter clamp and saw. Not sure how it all works. That's why I bought a processor and didn't build one  :D

[mike_belben]

Well i stand corrected.  Blockbuster still does use air.  I guess there could be considerable money saved using nylon lines, pushlocks and dc solenoid controls for the saw, clamp and tipper. 

[cascades]

Wow thats a crazy setup with the slide feed system. I wonder how it would go with less than ideal wood.

Im going to research all that hydraulic/ pneumatic stuff you mentioned Mike. Im not too good with more complicated hydraulic stuff, trying to learn as I go.

the cylinder i'm using is a 8" x20", 2.5" rod diameter. Ive got a big vane pump i'll use to drive it, I think its about 50 gpm, not super sure until I check it out. That would give cycle time of about 10 seconds. Ill confirm pump size when I have a look at it. Im going to run independent circuit for the saw, so I can split and saw simultaneously. Probably run at 2500 odd PSI. 

Makes me want to pull my hair out looking at the Parker, Vickers etc websites, so technical, so much information! Maybe I need to read a book on hydraulic systems. 

Gotta figure out what sorta power I need for the saw, so I know how big a diesel I need. 

That video of the dibble processor is the type machine i'm going for. 

[mike_belben]

A friend of mine ran a multitek with the suspended grapple that grabs and advances the log.  Hed run numerous others and said it was the best in twizzler stick wood that conveyors and powered rollers would get hung up on.  


Initially i wanted to replicate that and could, but then realized no piece of wood refuses to lay still on a platform thats moving.  Nor does any refuse to do what its told when in a choke hold as the carriage retracts out from under it.  My clamp will differ from the one i linked and the halverson setup but i think its a brilliant feed solution.  Have you priced out conveyor chain or rubber belting or a dozen bearings, shafts, sprockets, chains drive motor hoses valve?   It can all be eliminated with a slide table run off the splitter ram that u need no matter what.



One good thing about your monster ram is that it doesnt need the high psi to make the same force as a 4 or 5" ram.  So you can run a larger displacement pump to speed flow up.  


50gpm @ 2000 psi takes 65hp

50 gpm @ 2500 is 81

50 gpm @ 3000 is 97

97hp is good for 75gpm if you only need 2000 psi.  But the flip side is 75 gpm is huge components. Excavator valves.

[Nathan4104]

Lots of great advice here, i wish ya luck in your build!!
For what it's worth and it was mentioned earlier... the splitter speed is not always the bottleneck in speed it seems.  Sure the faster cycle time is great and is noticeable as you cut.  But, getting wood onto the table and getting the splits away from you can rob your production time.  Having a good work flow will save as much time as that fast splitter.  A conveyor that takes the splits away without any fuss is worth a huge amount of time.  
I'd build your machine to cut the 90% of the wood you normally see. Deal with the large 10% with a saw. 
As for speed, I recently tried out a new Hakki.  It's cycle time was fast. apparently it uses high pressure,(5000psi?) I don't understand it but the sales guy thought they used 2 cylinders... as one retracts it's return flow is used to beef up the extend of the other? 
Also, my processor does not have a log clamp. I cut wood in the 3"-16" range.  (.325 chain).  it does not need a clamp.  it can easily be held by hand or not at all.  a manual clamp would be faster than a hydraulic one as well. watching different machines that clamp always adds an extra second or 3 in the cycle time. 

[moodnacreek]

If I was to build a firewood processer, this is how it would start; [I am in the northeastern U.S.] Watch the flyers for sawmill sales and attend ones that had log troughs and or L&M cut off saws and log infeed decks. From actual experience I can tell you it is cheaper and heavier to buy this stuff at auction. Now for a few thousand bucks we have 2/3rd. of the machine built.  For power I would look for a 401 ford diesel, F 700 school buses especially had this bullet proof, very long lasting engine. This would drive a triple pump as big as the 100 + diesel would take. The hard part here is to adapt the pump to the flywheel. Worst case is short truck style drive shaft. Should you come up with an s.a.e. flywheel it is just $.  I have no recipe for the splitter except I will say the ram should be 4 1/2" + , custom made with the largest rod possible.

[mike_belben]

@Nathan4104 that sounds like a regenerative stroke circuit where you direct the exhaust flow of one side to the infill of the other side in order to speed a linear hydraulic motion, instead of exhausting from cylinder to valve to filter to tank and drawing fresh oil from the same distance.  You utilize the syringe effect and take fluid thats already nearby.  Theres some funky pressures and valving but its a technology that works. 




I have been a junk man my entire life.  And from my own experience i can say that very few people will get every single right fitting part for a good working machine, from their scrounging adventures alone.  You can get most of it -especially if you have been collecting for years or dont mind starting the project in a few years to keep hunting- But at some point youve got to go to the store and buy. 


 There is no glory in working 6 months to build something that isnt good.. But oh it was cheap.  If youve got the right ram, the right valve and the big engine, dont settle for the random i think itll work pump, or build a hotrod system then try to put 3 lawnmower engines on it.  Buy the EXACT right pump or engine or valve to fit your other ingredients perfectly.  Dont rube goldberg it to save a buck or the whole project is for naught.  Ya dont grow cukes then put chilli powder or curry in your pickles as a substitue for dill and then say lets eat em anyway the curry was free and dill was too expensive. 


Its not weakness to compromise if it gets you the best outcome... Its wisdom. 

That was the long way of me saying dont worry about the cycle time.  If you dont have 2 extra seconds for a split, then you dont have time to build, fix, redesign, rebuild, maintain and run a machine.  Choose one.  Fast, or 8" ram.  

[Corley5]

The K.I.S.S. Principle applies to firewood machines 😉🙂😎. You need to ask yourself if you want to build a firewood processor or process firewood.  I bought a machine and went to work 🙂. 

[cascades]

Thanks for all the great advice guys.

I guess half the fun/ point is the project haha. I can build a machine with 20k worth of parts and my nouse. Wouldnt get much change out of 100k to buy a machine ready to go where i'm from. Nothing comes close to the buzz when all your hard work pays off and you see those bits of wood start piling up, without having to touch em. The time I spent building it will soon pay off because it all of a sudden takes 10x less time to produce a ton of wood. Adds up quick when i'm doing a a few hundred ton a year.

So Im thinking ill have to run 3 pumps. 1 for split, 1 for saw, and 1 for all the auxiliary functions. i'm thinking ill need around a 150 horse diesel, hopefully i can find a tri drive setup for the pumps sometime in the next few months. 

Open vs close centre i'm not sure about. I cant get my head around it yet, unsure if the extra cost is worth it either. Ill do a bit of research. Why i'm hoping to find a schematic for a professional one, help me visualise how it all works. 

[mike_belben]

In open center you have a constant circular flow at almost zero pressure,from the tank to the pump to the valve and back to the tank.  When you move the valve you are blocking the path back to tank and simultaneously revealing the path to the cylinder or hydraulic motor.  The blockage creates resistance to the pumps flow and pressure rises until the load moves or the relief valve pops to prevent explosion.  



In closed center you have a pump with a swash plate that tilts to vary how much volume comes out of the pump, and in the case of hydrostatics they can also change flow direction on the fly too. So the engine can be at WOT but the pump can put out zero.


Open center is a lot cheaper and simpler for the casual user.  The hydraulic schematic on a skid steer will boggle most people. 

I understand the desire to DIY. Nothing wrong with that.

[moodnacreek]

Mike, every do any business with Chuck Lupinsky aka lps.  machinery? It's in your state.

[mike_belben]

No sir.  Friend of yours?