Hi everyone,

I'm new to this scene - just starting out speccing what I want to be an all-purpose CnC machine. My backround probably like quite a few people here is computing, with music (songwriting), speaker building, electronics, motorbiking (not any more), hobbyist robotics ad general invention.

My aim is to build a machine that is capable of:
- routing in 18mm ply / hardwood
- fine engraving / HDPV mould cutting
- aluminium sheet part cutting / drilling
- PCB etching / drilling
- soft part milling

I'm going to be looking for advice because this I know is ambitious - since this is a hobbyist machine I can happily sacrafice speed for accuracy, but I want a very rigid load bearing gantry, and from what I have seen so far I simply cannot afford supported precision profile linear bearing systems.

I might be ok, because the machine wll be at most 800 by 600 mm x/y.

So, for my first question:

I currently plan to build the X axis sliders as 2x 20mm round bar, supported at ends, such that the gantry will be supported by 4 ball sliders (two on each bar) on each side. I am hoping that this will more than half the sag/play if a single bar was used.

I will use a chinese preloaded ballscrew on each side of the X axis, between the two rails:

side view

============== <-- 20mm round bar

;;;;;;;;;;;;;;;;;;;;;;;;;; <-- ball screw

============== <-- 20mm round bar

The ballscrews will have toothed pulleys on, and will be driven by a single stepper via a toothed nylon/kevlar belt.

Any thoughts on this? I am thinking that this must be a quite standard train of thought for a rigid machine.

Best wishes all!

Also, I'm based near wimbledon. I will need to make some custom parts - anyone want to help me spec or give me a quote for some machining of custom parts?