Planning my first CNC machine

[pippin88]

Have you found a commercial machine that uses your structure / axis setup? If you can't, that should tell you something.

I've never seen one (and I've spent a lot of time looking at machine frames / designs).

There are large machines with a Y axis at the bottom, a lifting Z beam, and X axis travelling across the Z beam

Axis naming convention for a vertical machining centre:
Standing facing machine
Z goes up and down
X goes left and right
Y goes forward and back

[routerdriver]

My concern is mainly that the movement on the designated X axis may not be accurate.It is analogous to a wide drawer and they are prone to jamming or going out of square quite easily because the short runners aren't long enough to provide directional stability and I suspect that the same situation will pertain here.I strongly suspect that a moving table on the Y axis only will be better for stability and a Z axis with bracing,that traverses the gantry would be better.I would probably go for some external diagonal bracing on the X axis too.What family of steppers are under consideration?

[JohnHaine]

By the time you have bought all the materials it might be as cheap to but an off the shelf XY table and convert it. To build a machine you probably need a mill anyway,

https://www.arceurotrade.co.uk/Catal...able-400x145mm

Or buy a complete mill and convert that. You will learn nearly as much and have a higher probability of success and of achieving the accuracy level you want.