Newbie- First CNC ever

[Zatar]

Hi all,

I'm new here so I don't really know if this is the right subforum. Sorry if it isn't.

Electronics is one of my hobby's and for this I need to make PCB's (and drill them ), front panels and lots of other stuff.
Because getting started with the chemicals isn't very healthy and the cleanup takes a lot of time I would like to make some CNC equipement.

I would like to be able to make pcb's and drill them, work with MDF, plexi and thin aluminum.

I've already seen lots of DIY CNC machines using stepper motors from printers etc. etc. But I've been told that Servo motors would be of better use since they have higher speed and accuracy.

My first couple of questions are:
- Which do you think is best? Stepper motors or servo motors?
- Is a working space of 300mm x 200mm possible for a home machine?
- Any other starter tips?

Thanks a lot!

P.S. I'm still a electromechanics student so I'm kind of on a low budget

[Gir]

My first couple of questions are: - Which do you think is best? Stepper motors or servo motors?

Servos are "best", but steppers are far cheaper and far more practical for what it sounds like you want to do. If you have the spare money, however, servos would be better for PCB's. But be prepared to spend a few hundred extra.

- Is a working space of 300mm x 200mm possible for a home machine?

Well, considering that a lot of us have tables exceeding 1 meter, I'm pretty sure your's is possible

[Zatar]

Thanks Gir.
For the moment I'll start of with stepper motors. If I get that working I can always get a new servo driver and replace the steppers by servo motors.

I don't know anything about this project yet so maybe I'll start with the stepper driver circuit? Is this one a good one? -> Link

If so... Can I make it more safe by adding some optocouplers between the parallel port and the driver circuit? (still have to find out how but I guess it would be 'healthier')

[Gir]

These boards are very simple and not very good. You're probably better off going with a gecko, but if you're trying to save on money and feel like assembling your board, hobbyCNC makes pretty good boards a good price, and their motors are very hard to beat in price (for their size).

How much money are you looking to spend on this project? Money can make quite a difference

[Zatar]

Well at the moment my budget is very small (actually I have no budget yet ). I do have a lot of electronic components at home and I can make single sided PCB's myself. -The chemical way, never tried double sided before-

I'm willing to spend some money on it while the project continues. Since I get €25/week I'd say every month about $150? So a total of ... about 800 - 1000 dollars I guess.

Would like to do most of the electronics myself though since I want to learn electronics and be able to repair what I build myself

[jans123]

On a tight budget? As a first project I tried the combination of steppers from old floppy drives (5 1/4 “) some ULN drivers and an old PC with a parallel port. Software from www.dakeng.com was the glue between man and machine. The ULN circuits were soldered on some Veroboard, power came from the PC and that’s just about everything. As lead screws I first used simple M3 threaded axles and as guides some cheap stuff from a hardware shop, probably intended for light drawers. Yeah, the lead screws probably won’t last long, but they have some 50hours effective and that is actually a lot of experimenting and cost was near zero. Nuts was at first threaded holes in aluminum bars (I didn’t have any brass at hand and it was a quick and dirty weekend project). When the lead screws and he nuts are worn out it’s no big deal replacing them. The traverse forces are amazingly strong (it is a fine thread…). The working hardware was a cheap DREMEL copy and the whole framework is plywood.
For the simple electronics the motors had to be unipolar and care was taken to keep the current acceptable and the voltage as high as possible to get the speed up. I.e. resistors was used to burn excessive energy.
/ jan
p.s. If you put something on fire, kill a computer, cut a limb in the machine or whatever mishap would occur don’t blame me. I’m an engineer and usually know my limits, but I don’t know anything about whoever read what I write.