Hi Tracy,

Two things.

20cm high is very low. specially if you want to put pnuematics in there. make it a little higher please, like 30cm or so.

Either your ram is very wide and very short (4 wide, 0.7 short), or very narrow and still a bit short (0.7 wide and 4 short). Either way not very suitable for an axe. Also at what pressure will you be operating the axe?

As a reference, this is my axe:
120mm bore (wide), 200mm stroke (long), running on CO2 at 16 bar. That gives me 1800kg of force on the ram when it pushes, and 1700kg on the return. That is because there is the rack that slides in and out the ram that takes up space where on the other side there is gas. So one end of the ram is less powerful than the other. On the other hand it fills more quickly since it needs less gas.

Hope this helps.