a little over a year ago i built a 3ph splitter (i only had to buy the valve, cylinder, lines, fittings, and pins - the structural parts were pretty much all surplus collected over the last 10 years. i have two new regency wood burners - one medium and one large. by my opinions, neither of them are very big, but they do produce a lot of heat and don't use much wood. i have to cut all my wood 16" long to be able to fit both stoves. i also cut it to 4" or less diameter due to the door size.
i was planning on the same vertical approach because large pieces are too awkward to lift and balance, but an uncle basically told me to rethink because since it's a 3ph, i can drop it flat on the ground. i used a 4" beam when i built it, so it sits low enough that very large logs could be rolled on it. this eliminates the need for the vertical option. after using it, i find that i like the beam very high. it puts the work at a level where i'm not hunched over to operate it. if you have/add a small table then the wood will stay at level so you can break the large pieces down into smaller ones without bending.
i built my splitter very small (3-1/2x18 cylinder, 19" log opening), since the power source is also small (jd770-5.6gpm). i reasoned that i don't often split extremely large hardwoods, and i can't use over 18", so why wait for a 24" cylinder to take up the slack after it cycles back. if you buy it you generally get tops, and are 16" and under for good burning hardwoods. to date, i have only split logs that i have dropped around the property, and nothing over 12", but it went through those with ease. i'm sure i'll eventually have something it won't handle, so i may have to occasionally saw a log in half, but it hasn't happened yet. besides, in my mind it's criminal to turn large hardwoods into firewood. with the price of good cabinetmaking lumber, i'd turn large logs into lumber before i burned them.
