Building a Commercial Firewood Processor

[akwoodsman]

Hello! I am looking into building a firewood processor for my business. I would like to produce 3-4 cords per hour. I will be processing paper birch and White spruce. I am thinking of running a 80-100 hp diesel engine. I am wondering a couple things. what kind of cycle time would I need to produce that. average diameter being say 8 inches. also how do I figure out the size of hydraulic pumps I need?

I am going to build something almost completely automatic. the in feed rolls the log forward to a specified distance clicks a switch. then the chainsaw falls when the switch is tripped. the log falls into a v shaped basket. when the splitter is in the starting position the basket is allowed to tip. that hits a switch which tells the splitter to split. meantime the next round is being cut into the basket.

any thoughts, ideas?

[AnthonyW]

I have contemplated building a firewood processor myself. I haven't done the math, but it isn't hard.

If:
1 cord = 128 cu ft.
1 8" diameter log 16" log is 0.6 cu ft.
You would need about 216 cuts per cord.

For three cords per hour, that multiplies to 648 cuts per hour, or one cut and one split every 5.6 seconds.
For four cords per hour, 864 cuts, or one cut every 4.2 seconds.

I used a square log (opposed to round) because there is some air space between the firewood pieces when stacked. The difference is 0.465 cu ft round vs 0.6 cu ft square.

Four cords per hour is going to be hustling. That's for sure. Larger logs would of course reduce the cuts per hour.

To figure the pump size, we will need to know the GPM required for the chainsaw motor and the capacity of the splitter cylinder you have selected. Also what other hydraulic implements will you have?

So far you have the chainsaw GPM + cylinder capacity * 15 (number of splits per minute) * 2 (extend and retract) + extra just in case capacity (25-50%)

[akwoodsman]

yeah the 8 in is just for the birch. spruce averages more like 12 in but the demand for birch is much higher in alaska. so the chainsaw will be operated by hydraulics, the splitter, the basketand, and the splitting wedge will all be hydraulic. I am going to call multitek because they have some models that run that fast and see what they use.

[akwoodsman]

this is a handy tool!!

http://internationalhydraulicsus.com/logsplitter-speed-calculator/

it tells you the cycle time of a cylinder based on GPM and size of the cylinder

at 40 GPM im running a 5 second cycle time. '

I'm thinking 3 cords an hour is much more attainable than 4 now.

[cp881]

Another way to speed up cycle time of the splitter is to run a large dia. rod , but I think there is different valving that you need to use that type cyl.
  Big difference in 3-4 cord per hour on paper compaired to the real world.

[akwoodsman]

would a bigger rod be less tons of possible pressure? because of less fluid in the cylinder? or doesnt it matter? Sorry I dont know much about hydraulics. yeah a 4 second splitter time would be optimal. With that I should be able to do at least do 3 cords an hour I think. to do a 4.2 second splitter time I would need a 40 GPM pump 5 in bore and 4 in rod. that is with a 24 in stroke.

[AnthonyW]

How are you figuring 40GPM? I'm not saying my math is correct, but here are my figures.

5" diameter x 24" length = 471 cu in = 0.27 cu ft = 2 gallons

2g capacity * 15 stokes/min * 2 (in and out)= 60 GPM.

Plus you need some GPM for the chainsaw drive and some extra.

[Corley5]

Buy a machine and start processing.  If you've got the markets for firewood the money spent on a machine will be returned faster than the time, effort and dollars spent building one.  That's my two cents  ;D

[NWP]

Buy a machine and start processing.  If you've got the markets for firewood the money spent on a machine will be returned faster than the time, effort and dollars spent building one.  That's my two cents  ;D

X2 

[akwoodsman]

you are correct if you have no rod in the cylinder. 5*24 has a volume of 471.23 in^3 but you have to subtract the 4 in rod at 301.6 in^3 which equals 169.63 in^3 which translates to 0.73 gal, which is 22 gpm at 4 sec times but then you have to look at efficiency of pump which could be anywhere from 60 -85% efficiency so then you get somewhere between 37 GPM for 60% to 26 GPM at 85% efficiency. I didnt calculate it the first time the computer did. But you also have to account for frictional losses depending on temp of hydraulic oil and weight of oil. as well as frictional characteristics of your seals and hoses. the chainsaw will be on another pump, the splitter will have a dedicated pump all to itself to maximize the ability to split efficiently.

Buy a machine and start processing.  If you've got the markets for firewood the money spent on a machine will be returned faster than the time, effort and dollars spent building one.  That's my two cents  ;D

X2 

unfortunately I'm 19 and even though my credit score is around a 730, the banks feel that with no collateral they dont want to hand me 60 k to buy a processor that does 3-4 cord an hour, however i am working on a work trade with a friend who owns a welding shop so as to front me the steel until i can repay him next july.

[DDDfarmer]

[/quote]
unfortunately I'm 19 and even though my credit score is around a 730, the banks feel that with no collateral they dont want to hand me 60 k to buy a processor that does 3-4 cord an hour, however i am working on a work trade with a friend who owns a welding shop so as to front me the steel until i can repay him next july.
[/quote]

Warning bells going of in my head on this..  I don't like owing my friends anything more than a few bucks.  Knowing what steel costs and a idea that you will need a lot, you will be owing quite a bit.  If something were to go wrong could cost you your friendship and more.  Personally I would look into other options, but its your call.

[cp881]

would a bigger rod be less tons of possible pressure? because of less fluid in the cylinder? or doesnt it matter? Sorry I dont know much about hydraulics. yeah a 4 second splitter time would be optimal. With that I should be able to do at least do 3 cords an hour I think. to do a 4.2 second splitter time I would need a 40 GPM pump 5 in bore and 4 in rod. that is with a 24 in stroke.

The larger dia rod will only effect the power of your return stroke

[Corley5]

Buy a smaller processor first to test the waters and get a bigger one later if it works out. 

[akwoodsman]

The smallest processor I would go with would be like a HUD-son  wolverine. Capable of doing 1+ cord an hour would cost me close to 16,000 with out a conveyor. I should be able to build one that can do 3 cords an hour for around 20k and i think that's a generous figure.

[North River Energy]

AK,
Do you have a conveyor, and an effective means of loading the deck?

Are you planning on stockpiling, loading to your own truck, or loading to a hired truck?

What length block?
How many splits per block?
Do you have access to heavy machinery salvage, or do you have to source all components as new?
Do you actually have 20K to work with?

[Oliver1655]

As the wood you will be splitting splits easy, you might consider starting with building a dedicated horizontal splitter using a 4" cylinder & a 28 gpm 2 stage pump with a 4 way wedge.  This will give you a cycle time of 5 sec.

Have out feed tables attached to you splitter which will feed the wood to a conveyor.  A conveyor/elevator to carry the wood away from the splitter & either dump into a pile out of your way or into a delivery vehicle will be a big time saver!

Use a narrow knife edge for your wedge. 1/2" - 3/4" thick cold rolled flat steel will work fine for your 4 way.  3 of the 4 edges on mine are 1/2" & I split elm, hedge, ... and I have had no problems with it holding up.

Then build a staging table next to your splitter you can fill up so when you start splitting you are not wasting time gathering up rounds to split.  If you have a helper you could keep the splitter going all day no stop except for breaks with them keeping the staging table filled.  If you are working on your own, just run the engine on your splitter while splitting & turn it off while loading up the staging table.  This will save you a lot on fuel.  Another option to a staging area would be to have 2 or more smaller carts which are easy to move around.  You can fill it up with rounds to split then when one is empty exchange it for full one.  Your helper can stay busy cutting & supplying the splitter operator. Remember smaller carts which will be easy to unload from. 1-2 rows only, won't need sides, just ends, 1/4 to 1/3 cord max. 

If you do it this way there is no reason to waste money on an auto-cycle valve system.  A standard log splitter valve with a detente for the return stroke will work fine.

I would not spent the time or money building a log lift for your situation. It will not be needed if you incorporate the splitter into a processor down the road & is an unnecessary expense. 

Not counting steel you should be able to build it for < $1,500.

Then if business is going well, by the following year you should have the steel paid off & have money saved for future growth.  8)

You are young & full of energy.  You will find with a good chainsaw in the 60 cc range you can cut up a lot of wood in a day.

I believe you will be able to net a greater profit if you stick to a hand held saw & the above mentioned splitting setup working on your own or with one helper/partner versus buying a processor.  There have been many established fire wood producers on the various forums I visit who have discussed purchasing wood processors & most of the discussions end with them not getting a processor at this time.

Another thing to consider is what you will have to pay for having employees. Social security, workman's compensation, liability insurance, personal protective equipment (PPE), ... Instead of paying minimum wage, each employee will cost you close to $25/hr.

So while having 1 helper will greatly boost you production & is smart for safety in case of injury, additional full time employees may not be cost effective. 

Rather than spending a lot of time delivering, you might consider subcontracting it out while you are getting started. This will decrease you start up overhead especially if they will supply the truck/trailer & you will not be responsible for the extra employee costs.  Just let your customers know you have a person who is not your employee but does hauling & who would be willing to do the delivery for them.  Have and established charge list for delivery and/or stacking. 

Delivery:  Using a dump trailer or dump truck will save time.  Determine how much wood it can hold by:  1 - Filling it up with tossed wood then dumping it out, stacking, & measuring.  2 - Stack up a cord (4'x4'x8') & toss it in the dump bed to find how full it needs to be.  THEN - I would toss in another 10-12 pieces to insure you never deliver a short cord.  Delivering a short cord is a big no-no & the word that it happened will fly through the gossip grapevine so fast your head will spin. 

Good luck on your endeavor. 

[akwoodsman]

AK,
Do you have a conveyor, and an effective means of loading the deck?

Are you planning on stockpiling, loading to your own truck, or loading to a hired truck?

What length block?
How many splits per block?
Do you have access to heavy machinery salvage, or do you have to source all components as new?
Do you actually have 20K to work with?

I would be building a conveyor and have access to a loader with forks. loading to my own truck and dump trailer as well as stockpiling. 16 in blocks 4 splits for most birch, 6 splits for most spruce.

I have access to some salvage. 20k not yet i dont.


Oliver1655,

I think your idea is what I will go with for now. I have a 17.5 hp motor off of a lawn mower that I believe should be adequate for the splitter. then I can use a smaller engine for the conveyor. the 28 GPM pump, the  4x24 3000 psi cylinder and the valve on international hydraulics will run me about $600 I hope that I could build it for under $2500. what do you guys think? oh and I run a Stihl ms361 with a 16" bar and a skip tooth chain. which works pretty well for me.

[AnthonyW]

That was my thought today. Now that we know the GPM, how does one determine the required HP especially if there are multiple pumps?

The 4 second cycle time is only for the stroke and does not include the reload time (ie., the time to set the next log in place and then trigger the splitter). Conservatively, I think that would 1 second per log therefore the cycle time of the splitter needs to be 3 seconds or a 25% increase in required GPM.

[akwoodsman]

yes, so at 40 GPM and a 4" bore and 2" rod 24" stroke you run a 3.5 second cycle time. if the 4 in cylinder holds up, its rated at 20 ton then i will reuse it if i build a processor. my fathers splitter is 22 ton and we have no problems with any of the wood we split. I'm not sure how fast I need it to be. it might be that a 5 second cycle time is fast enough for me after all. If its not, i will upgrade the pump and/or the cylinder when I go to build a processor.

as for hp the 28 GPM pump from international hydraulics has a minimum hp of 16, it said that on their website.

[dave_dj1]

One thing you have to keep in mind is valves, few valves can handle 28 gpm. Size them to take full advantage of your other components, another thing is the ports in the cylinder won't be able to handle 28 gpm. I'm not saying you cant't run one but I run 22 gpm and no problems, I have 30" stroke and a 4" cyl, with a fast enough cycle time to suit me. Heat is hydraulics enemy. Every restriction creates friction creating heat. Large capacity reservoir and maybe even a cooler.
good luck and keep us posted.
dave

[blackfoot griz]

One thing you have to keep in mind is valves, few valves can handle 28 gpm. Size them to take full advantage of your other components, another thing is the ports in the cylinder won't be able to handle 28 gpm. I'm not saying you cant't run one but I run 22 gpm and no problems, I have 30" stroke and a 4" cyl, with a fast enough cycle time to suit me. Heat is hydraulics enemy. Every restriction creates friction creating heat. Large capacity reservoir and maybe even a cooler.
good luck and keep us posted.
dave

Good point. Remember when ordering your cylinder to check the port sizes. You may have to have the cylinder made or modify the ports to allow that flow. I run a 28 gpm 2 stage on my processor, but, I only run the engine @ 2400 rpm. This is still pushing it with 1/2 inch hydro lines.

[GF]

my fathers splitter is 22 ton and we have no problems with any of the wood we split. I'm not sure how fast I need it to be.

Does your fathers 22 ton splitter split 6 or 8 ways, its simple for a splitter to split in half, splitting 6 ways is going to change the splitting force requirements, add a few knots and the requirements for splitting will go up even more.  Blackfoot griz has some great background knowledge on building a firewood processor.  When I built mine I had the cylinder ports modified to accomodate more GPM, 1/2" ports is not going to allow for a fast cycle time.   Also if you have access to a metal lathe and milling machine it will be very helpfull.

This link http://www.cylinderservices.net/store.asp?pid=10726&catid=19717 provides some good information on the maximum flows through different size hydraulic hoses and hydraulic tubing.

GF

[AnthonyW]

Very useful link, GF. Why do you say the lathe and milling machine will be useful? (especially the lathe)

[GF]

I used the lathe to true up round stock to attach the chain sprockets to, I also used the milling machine to cut the keyways in the round stock for the sprockets, milling the six way splitter edges, and also for creating elongated holes for bolts to slide in when adjusted the bearing blocks to increase tension on the conveyor chains, etc.  Below are some images of the one I completed in 2011.  The thread of the build is located in the "Drying and Processing" board or this link https://forestryforum.com/board/index.php/topic,40190.0.html .  Thanks to alot of other forum members for the advice and ideas they shared when I was going through the build process.



 



  



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 



 

[beenthere]

Have an action video of the processor? Looks great, and presume it is as good splitting wood as it looks.
Nice build and finish.