Hi all,

I'm thinking about investing lots of time in reading up and learning about home-brew CNC, but before I got all excited and invested in it, wanted a reality check so figured the best place was to join up on here, start some reading and start some question asking :)

The intention is to build a 3-axis CNC machine, the intention being to do the following :-
  • Aluminium parts (mainly automotive, miscellaneous bracketry, etc)
  • Plastic/acryllic (mainly project boxes for the below, but also potentially just fun stuff)
  • PCB boards (as an alternative to acid etch)


I suppose if I had to ditch one of those then the PCB board fab can go because in reality I can always continue to acid etch them and send them off for fab on big runs.

The main thing is I want it functional, useable, it's not just as a learning exercise, it's got to do a personal hobby work that's of a decent level of quality and repeatable. I don't need to do it fast and I don't want it to end up costing the earth, but likewise there's no point cutting corners if it's just going to cost me in the long term. Once built, I'd like it to remain a tool in the stable for years to come!

From what I can gather from basic skim-reading... please tell me true/false where you see fit!

1) Linear *supported* rails are really the only way to go without getting frustrated in the long term.
2) I'm torn between frame. MDF is clearly out, but it's whether to go alu frame or steel? I can weld, I have plenty of tubular steel, but I'm concerned about accuracy of construction. I've seen plenty of commercial offerings and all seem to use alu frame; if I can go that route I'd be more confident in the construction I think, but will I get the accuracy of build I need, or does it make no difference? I understand the pressures the machining will put on the chassis; if I mimic an existing design that uses alu extrusion I presume there's nothing that says I won't be able to machine the bits I'm looking at above?
3) Go proper balls screws, avoid the temptation to use cheap threaded rod, belts, chains

The electronics I'm not really worried about, likewise everything computer-related (I'm in IT myself). Was thinking linuxCNC at first, in terms of controller board I've yet to look into anything. Something USB-based would be good rather than parallel port. Was planning on getting the basics understood first before I invest too much time in the finer details...

In terms of CNC itself, no previous experience whatsoever. At all. Most of it swooooosh, straight over my head :) but I still stare in fascination at the 5-axis machines at Autosports every year :D

Anyway, thanks in advance and apologies for the plethora of dumb questions that will undoubtedly follow :)

Cheers,
Dan