Quote Originally Posted by JAZZCNC View Post
CAN NOT STRESS ENOUGH. . . . . .DONT DO IT. . . . ABSOLUTLY DONT DO IT.

You will regret using unsupported rail and even more so on the Z Axis.!!
Simon, I'd really listen to this advice. I know you think you know what your letting yourself into here but honestly, you have no idea. I mean that in the nicest way possible.

I had to have my Z-axis rebuilt because it was using unsupported rails and was shit. About +/-1mm of flex at the bit and that means you'll get a crap finish even in MDF with anything like a decent DOC and feedrate. Your parts will be undersized, oversized and generally a mess. And you can forget it if your thinking of aluminium. Plus your using a heavy spindle with heavy 16mm alu plate. That's a bunch of weight right there before you've even got to the cutting forces.

Do your self a massive favour, ditch it and go with supported round rail. It'll add nothing to build complexity and hardly anything to the price. Cannot stress enough how shit round rail is, it should be banned on anything calling itself a decent CNC router.

Listen to the knowledgeable folks on here and save yourself from a world of pain, you'll get you a much better finish, more accurate parts and will let you move up to harder materials like alu, Corian and so on.

I'm trying to stress this because I fell in to the same trap your about to and its costs me a lot of money to put it right. Do it right the first time.