Bought a cnc machine, need a lot of help

[Doddy]

Ah, I saw that on eBay when yo first posted, there's a couple of warning signs that you might want to address, see bottom.

Some very quick replies to the more basic questions:

"Stepper 23", I think you mean NEMA23 Stepper motors. I'm curious as to why the seller removed these from the machine.

Port can be parallel, can be USB. You'll need a Break-Out Board (BOB) that matches this. You ask which is best, there's many views, mine is that the UC300ETH is a good interface to the PC, using ethernet which would improve the comms robustness (vs. USB) and the PC processor loading (vs parallel), but adds £100 to the budget. You'd still need a parallel BOB (£5-10) as well.

The use of an old PC and the PC PSU?, a standard PC PSU offers +5/+12 supplies (maybe a dollop of low-power -ve supplies as well) - these would be of limited use - perhaps for the BOB logic supplies, but you're looking at somewhere between 24V-100V for the stepper drivers (depending on model used) - you could get a separate switched-mode PSU and mount this inside the PSU case, or make your own linear supply but this is moving further away from a standard "as-is" mechanical fit to a PC case. It's a cheap option, especially if you have a case lying around but go into this with eyes open.

About that machine - it looks like an awful lot of this is 3d-printed, including the spindle mount. This will likely compromise the rigidity of the machine - you should be mindful of this and understand if this is impacting your work - you can start to replace piecemeal.

I'd also start thinking about replacing the cabling with shielded CY cable to avoid problems with electrical noise from either steppers or spindle.

Hmmm, what is the drive system on the axis?, from that image it looks like this could be simple threaded bar - if so you might encounter problems with backlash and general accuracy, you could start to look to replace with trapezoidal screws (cheap) or ball-screws (not so cheap). But I'd get the basic machine up and running first.