Hi all.

Apologies if these questions have been asked (individually) before but I thought I'd post this as I'm having trouble deciding on a few aspects of my forthcoming CNC build.

The intended purposes of the machine are:

- Cutting plywood/MDF and acrylic
- Occasional cutting of sheet aluminium (making cases for electronic projects) and
- PCB milling, cutting and drilling - through hole stuff so not massively fine work

I am primarily an electronics hobbyist (so electronics won't be a problem) but I don't have a huge amount of experience with the other required skills - I can do rough carpentry (to the point of having built a small timber framed building and several workbenches) but I'm not so experienced with finer work; I have a bit of metalwork experience such as drilling and tapping aluminium and some welding but again, not much.

I only have a limited range of tools - jigsaw, circular saw, drill and drill stand.

Thought it was worth mentioning these things as I know they all have a bearing on the decisions I make. So...

I am trying to build a small (maybe 30x30cm work area, bigger is better but I only have a tiny workshop) CNC router on a budget (I bet that's what they all say, but seriously, I don't want to spend too much money on it).

I already have five NEMA 17 stepper motors from an old 3D printer project, so I want to re-use those. I think these motors should have enough torque to run a relatively small machine like mine. Is this correct?

There appear to be a few options for the framework of the machine. Quite a few people seem to have gone with MDF. Will this be rigid enough for my purposes?

The other popular options for DIY appear to be aluminium extrusion (expensive) or even welded steel frames (I'm concerned I won't be able to do this with the required accuracy, so I might as well write that off right now, and also it may be overkill for a relatively tiny machine). Are there any other options I should consider?

Linear slides. Again, there appear to be a few options here:

- Hardened steel round rails and linear bearings. These are attractive to me as they are relatively cheap and you can get linear bearings contained within a mounting bracket (SCxUU). What are the disadvantages of this? If I do go this way, should I choose 8mm rails or would it be prudent to go bigger (and, although I've not looked into the cost, presumably more expensive)?

- Hardened steel rails with bronze bushings. The bronze bushings are slightly cheaper than the ball bearings and presumably more accurate.

- Rotary bearings (i.e 608 bearings or similar) arranged at an angle. This seems to be quite a popular option for DIY machines but I have concerns about being able to drill the brackets accurately enough to get everything to line up.


Can anyone advise?

Thanks. :)