Lowcost capable CNC - Make vs Buy?

[Andrewg]

Your way way over thinking this.!! . . .

That is what I need - Keep me focused on the real issues


Yes this is what I aspire to:Neat, clean, capable looking machine!
From your previous posts I am assuming I am looking at
- 45x90 extrusions on Y axis with two for the L gantry.
- 12mm Plate for ends and gantry sides
- 20mm linear rails all axis
- 1610 ballscrew, 1605 on Z driven via belt and pulleys so steppers can be tucked out of sight, 1: 1 gearing? is it worth added parts?

A little worried about the X/Z carriage getting complicated. If rails on front face and ballscrew on top, then couldn't it be a single plate again?

I am assuming this design cannot cut beyond the table, but by removing the gantry sweep back and maybe mounting the rails on the face of the gantry (and removing the control panel) I could create sufficient over run.

The smaller closed-loop motors (<=3nm) all tend to be 3 phase

The ones I was looking at for price were like these appear to be just steppers with encoder and therefore not 3phase though these look similar but are described as 3phase and are £40 more so guess your advantages of 3phase closed loop will cost a little more. Know little about steppers besides frame size (NEMA) and torque (Nm) plus a vague idea that inductance needs to be worried about.

Don't use 15mm for the Z-axis as it makes more difficult to build regards clearances and they are fiddly. 20mm cost very little extra and make for a much stronger and easier to build Z-axis.

Again feedback from real experience appreciated. How much should I be worried about keeping Z axis weight down? I was assuming that on a small machine, I want to keep the weight being flung about to a minimum to ensure good acceleration and performance whilst allowing modest (lower cost) motors and drivers to be spec-ed.

Working on a Z axis, need to upgrade the rails to 20mm!