hydraulics question re: building splitter

[Engineer]

I am going to start gathering parts in preparation for building a custom log splitter for myself.  One of the things that has been bugging me is the proper size of the different components relative to each other.  I don't want the splitter to get stuck all the time, yet I don't need it to blow through an elm log sideways either.  Cycle time is important (less is better) but I don't know which components of the system govern the cycle time. 

I guess what I need is some pointers, maybe a primer on hydraulic systems, so that I know the proper size for the cylinder, pump, hoses, fluid tank, and anything else critical to the main system.  I have not decided yet if I want to run it on a separate engine or off a PTO pump on my tractor, but I think that I will probably use the tractor.  Not the tractor hydraulics, but a spline-drive pto pump. 

Most of what I'll split will be pretty gnarly stuff.  The easy stuff, the straight-grained ash, oak, maple, etc.  I'll split by hand.  It's the 30" maple rounds, the wet pine with knots, the crotch pieces, the locust, hornbeam and other fun stuff that needs the muscle.  Also need a minimum 24" capacity, but more would be better, even up to 36".  That's obviously going to make a difference in my system as the little stuff can be done with a very small splitter or by hand.  I need some beef.  It also doesn't make sense to me to chunk it all up with my chain saw.

[Wallys World]

For a start you can go to Surplus Center web site and they have a hydraulic tech area that has a calculator for GPM, PSI, and all that stuff. Also Timber Wolf builds a tractor PTO pump model, you may want to look at it to get some ideas. I have been working on a re-design of mine and here is what I came up with. I am currently running a 8hp motor driving a 3000 psi 3gpm pump, plenty of split power but not a lot of speed. It is also belt driven. The fix - 13gpm pump direct drive off the 8 hp, 15 gallon hydraulic tank, auto return valve (I don't really like the idea of auto on the out stroke), and a "engine crane" to lift up the big ones. From what I've been reading the hrdaulic tank should at least egual the pump gpm to help keep the oil cool. Cool oil makes seals much more happier. northern toolhttps://forestryforum.com/board/index.php?action=position"> Note:Please read the Forestry Forum's postion on this company has a bunch of hydraulic parts as does Surplus Center.

[Woodchuck53]

Morning all, I built one from what was then Northern Hyd. and bought the 6 hp. Tecumseh with the direct coupled 11 gpm pump. Found a used 5" cylinder with a 2.750 rod 30" long. Installed a 2 spool valve, 1 with a return detent and the other for a cylinder assist side ramp for the really big ones. At the time they also sold a 12" and a 6" heavy gauge wedge. Bought both and welded the shorter one at an angle to the tall one to contact the block first. Have all this mounted on a beam long enough to mount a home made oil tank 30"x 8x8 sqaure tube stock and tongue for pull behind the tractor or trailer when I go to the woods. It has never refused me. I have since removed the top wedge and welded two wings of 3/8" plate a little back from the edge of the wedge to help the spreading of the block. All works great and when the kids where little would argue over who pulled the lever. Now that I'm older smarter and slower I let it take it's time. We figure with this combo we have 30 tons plus power avaiable. It has never found one it couldn't whip. Have a good one Chuck

[thecfarm]

Can't help you out on the the smart stuff,but the common sense I can help on.Make sure you get it a good working height.Mine is 31 inches high to where to put the wood on to the I beam.This is a store built one.I think they are all just about the same.Make it sure it will spilt vertical too.Or have some arms on the side to pick up those big pieces.I have to spilt vertical to get them down to size first.I hace spilt pieces up to 3 feet through before.I would not want them that big up in the air.If they went the wrong way it would break something.Vertical might be better.But since you're building it,you could have it both ways.I would also build a small table on the side you do not work on from.This way you have a place to put a half of split wood on to.

[DanG]

Unless you already have that PTO pump for the tractor, I wouldn't advise going that route.  You could get a seperate engine and a 2 stage pump to go on it for less money.  The 2 stage pump will speed up your cycle time.  Cheapest way is probably to buy the pump and drive it with a shaft from the PTO.  You could gear it up with a roller chain, if needed.

I've thought about building one that rotates, instead of standing up for those biggies.  If you could rotate it so that the wedge is on the side, you could just roll the log up to it instead of having to stand it up.

[GAV64]

I built one years ago, still runs fine and still is a project being refined. From what you have said it seams that power is more of what you need than speed. Mine is an 8hp kohler, 16gpm stage pump, 4 by 24 cyllinder, slip on 4 way wedge, auto cycle valve. The modifications i have the parts for is to add loglift and adjustable height wedge. I believe the cycle speed is about 11 secs, i have thought about adding more speed, easy, go to 13hp with 22gpm pump and leave the cylinder alone. Need more  power keep the 8/16gpm setup and switch to the 5 Inch cylinder & lose a good amount of speed. if you are going to split the toughstuff, crotchity stuff the i would go with 13hp22gpm with the 5 Inch cylinder, lot of power and decent speed. Northern use to sell a book on building you own splitter, i think it had a video too, well worth the dollars, lots of basic info. I bought the clevis anchors, wedge, logsplitter valve from them. The two mods that helped with speed the most was the autocycle valve and the 4 way, and they were easy to add after the fact.
With the current setup it will split as fast as i can load but i split mostly forest wood 6 - 12 inches.
when you build it keep these things in mind, as others have posted big tank to keep the oil cool (mine is not big enough and i will be changing it), filtration in the tank and down stream. You have to be able to adjust the center pivot (balance point) before you do the final weld up or it will be a beast to hitch up or when you un hook to the tow vehicle the hitch will come flying up. Remember when you add oil to the tank your balance point just shifted (very experienced with this point). every time you add or remove things the balance changes. Add lots of reinforcement to the beam, the forces are incredible, there are times when it gets into a tough log that i walk away because it looks like it is going to explode. good luck

[mike_van]

Jon, I have to agree with DanG on the pump - I looked at pto pumps for a little while, 400.00 +  gets you a small one.  Then, you have no second stage for the really knotty snotty ones. I don't know what size tractor you have, but in my case it's a 55 hp one, not something I want sitting there running at 2000 rpm [to get 540 pto speed] just to split wood. Not at todays gas prices, not for wear & tear either. I'd much rather rebuild a Briggs than  an IH 4 cyl.  I bought a Didier in '78 or so, 5 hp Briggs, 11 gpm pump, about 700.00 then. Still going, same engine, minimum 10 cord [full ones] a year, sometimes 20.  There's pics of it now in my gallery, I built a log lift, raised it up higher, added a 'woodcatcher' & even made it self propelled.   The vertical split thing is a like/dislike deal - Myself, I can't see bending, kneeling, whatever to get 3 ft diameter chunks onto that baseplate.  I've loaded 2 ft dia. oak with my lift I built, any bigger, I just use wedges first. Really snotty, a sharp chisel chain will make them manageable too. 

[ksu_chainsaw]

I built this splitter about 8 years ago now.  I used a 4x24" cylinder and a 16GPM pump on it.  I wish I would of spent the money on an auto detent valve, but the valves I used were free.





The two valves are mounted above the splitter cylinder.
The one on the left works the log lift- very handy for the big pieces.
I also set the hitch height and length so that when it is hooked behind the pickup, the tailgate will open and the split pieces will fall onto it.
I also welded on a chain hook to the back of the wedge, so I could run a chain from the loader bucket down to it and move the splitter around easier.





This shows the old lawnmower engine powering the pump.  With the pump below the tank, it will never starve for oil, causing pump failure, unless it is out completely  ;)

I have not found anything that it won't split, including forks from the hedgelines I was taking out.

the cycle time is fairly fast, I have to work to keep up with it most of the time.

Charles

[sawmilllawyer]

Engineer, I think this site will help you out, check out this link:

http://science.howstuffworks.com/hydraulic3.htm

[little Bark]

You can look at commercial splitter web sites and they spell out exactly what gpm and cylinder size to use.  That is what I did.  I picked out the exact splitter I wanted and used there specks to guide me.  I never did build one I ended up buying a used rental unit from a local hardware store. That had everything I wanted and was about 400.00 cheaper then what I could build one for.