</font><font color="blueclass=small">( Most home-made splitters are way overdesigned - which is to say they aren't really designed at all. They are an accumulation of available parts where the usual selection rule is "bigger is better".
But bigger is not always better. Bigger may be just heavier, hotter, and more trouble to move. A 4" cylinder runing at 2000 psi makes 25,000 pounds of force. If that isn't enough, your wedge is too blunt. A 5" cylinder is 50% more in every way - more output force, but needs more gpm to keep the speed up.
The main source of heat in a splitter is the viscous friction of shoving all that oil through all those fittings - even when there is no splitting going on. The answer is lower flow and using components better matched to the job. My 2 cents. )</font>
Although I do have a tendency to “over engineer” a few things, the size of the cylinder, pump, engine and H-beam I chose was taken directly from store bought splitter. Still, I ran hydraulic calculations (speed, force, HP required, oil capacity, etc) for just about every combination of ram/pump I could come up with before deciding what I wanted to use.
One thing to keep in mind with a larger cylinder is that it produces a higher splitting force when the pump is still running in it’s “high volume/low pressure” mode. As a result, I’m moving pretty fast for all but the really big/hard logs. This makes splitting quite a bit faster – especially if you are working with medium size/hardness wood that constantly causes smaller diameter cylinders to push the pump into high pressure/low volume mode. Run the numbers and you’ll see that a 5” diameter cylinder is faster in the high flow mode than a 4” diameter cylinder is at low flow. If you can stay under the high/low break over point of the pump for the majority of your splitting, a larger cylinder is actually more productive.
Even with a 2500PSI relief valve setting, 5” diameter cylinder and a splitting wedge in good shape, I’ve run across 20” hardwood logs that I had trouble splitting. You could see the H-beam flex!
