I am starting a log splitter project and ran across a good deal on a hydraulic cylinder. The problem is its only 3.5" bore. I was planning on a 4.5" bore. Is the 3.5" going to be big enough? I split about 8 chords a year and a little bit of everything. Right now I am using a 4.5" cylinder and it splits anything I have put on it. As far as plumbing it up, is there anything I could to to make it as powerful as possible? Thanks for any info I recieve. This site is full of knowledge.

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Originally posted by duster:
I am starting a log splitter project and ran across a good deal on a hydraulic cylinder. The problem is its only 3.5" bore. I was planning on a 4.5" bore. Is the 3.5" going to be big enough? I split about 8 chords a year and a little bit of everything. Right now I am using a 4.5" cylinder and it splits anything I have put on it. As far as plumbing it up, is there anything I could to to make it as powerful as possible? Thanks for any info I recieve. This site is full of knowledge.

If you want a lot of experienced logsplitter advice, on your post, I advice you to try Arboristsite.comThere are hundreds of guys waiting to help you out!

Basically your splitting force (tonnage), depends on Cylinder bore diam and relief valve opening pressure (max system pressure).
for every 1000psi a 3 1/2" bore push 4.82 tons of force
for every 1000psi a 4 1/2" bore push 7.95 tons of force

Your cycle time will depend on pump displacement (cui per rev), pump speed (rpm), and cylinder bore diameter (inch).

You can not get BOTH maximum force and max theoretical cylinder speed at the same time. Valves, plumbing and cylinder backpressure will create pressure drop during flow, and that will create power losses (heat).

The only thing you can improve with your plumbing is to minimize these heat losses, by avoiding sharp elbows, long hoses, by choosing a little oversized hoses and valves, etc. Basically minimize everything that restricts the flow. You will allways get full splitting force when cylinder stalls, and RV open to by-pass flow.

Hi Duster.. the 3.5 will work just fine.. unless you are doing it for a living or into wood that is really stringy and full of knots.. just use a 2 stage pump and keep your hoses a good size and everything will be fine.. i get a kick out of people building splitters with 5 or 6 inch cylinders and using 28 gallon pumps, man what a waste.. the majority of the time we split we are rarely on the high pressure side of the pump, most of the time we are running about 650 to 900 psi of pressure.

Thanks for the replies. I will try the 3.5" cylinder. Would it have a faster cycle time than a bigger cylinder. Once I finally get started, I will post some pics. I am wanting to build a splitter that hooks on to the back of my woodhauling trailer (wich I don't have built yet!)so I can take everything to the woods in one trip.

Duster you would be correct, smaller cylinders require less oil to fill so the times would be faster than with a large cylinder, just try to keep your hoses short and try to stay away from a lot of short 90 degree fittings, if you can use 90 degree crimp fittings on your hoses it's better than using 90 degree adapters on the cylinder or valves. try to keep the return hoses one size larger than the pressure hose, this will help with reducing back pressure .. this is a unit we built last winter--http://www.tractorbynet.com/forums/build-yourself/157420-show-your-homemade-splitter-pics-4.html-- its under glastron23 ... http://www.youtube.com/watch?v=03vjSN6Zs7c the video was during the test of the unit, we were setting the pressures/repairing small glitches... Jim