Video of my CNC milling circuit boards.

[MrBean]

I've made a small video of my machine milling Alans PICStep board. If you'd like to see it, you can download it from http://www.terry-is.f2s.com It's near the bottom of the "stepper drives" page.

Regards Terry.....
http://www.terry-is.f2s.com/

[HuFlungDung]

So Terry,

After having watched it, I'd say that if you have enough Z travel, I'd highly recommend that you shorten up your collet grip on that tool. It'll be a lot less buzzy if you do. Maybe get ahold of a ball end mill, without the hugely undercut shank, too, which will help with the stability of the tool's tip.

Whats the difficulty you're having with drilling the holes?

[MrBean]

Thanks for the tips on the cutting bits. I've been looking for some better one's. I've found someone who can possibly supply me with some in the new year.

The holes.....I've not been CNC'ing very long and don't have much experience to draw from. I'm not sure of any good ways to do them. For the PCB tracks I converted a GIF of the PCB artwork to a DXF, then imported into Mach2 to generate the G-code.

If you have any ideas on how to do the holes while keeping it all in "Register" with the tracks. I'd appreciate some help.

Cheers.

Regards Terry.....
http://www.terry-is.f2s.com/

[HuFlungDung]

Terry,
I'm not certain of what steps you'd take, but typically, all you need for hole drilling is a point to mark the center of the hole. Now, whether you can do this automatically with your software combo, I don't know. Worse case: load your drawing into your cad system, and manually plot points in the center of all the hole locations.

This can be done in the same dxf file as the milling toolpath, and that way, everything should stay in register. By using a different layer for the points, you can then blank everything but the points and you should be able to call up some kind of automated drilling cycle in Mach2. Someone else familiar with Mach2 may be able to chip in with comments on how to continue from there.

The typical gcode drilling cycle is simply a setup instruction (to the machine) to drill so and so deep, (such as G81 Z-.125 F2.0) followed by a list of XY points to move to. After each XY move, the drilling cycle is called and executed.

[MrBean]

Terry,
I'm not certain of what steps you'd take, but typically, all you need for hole drilling is a point to mark the center of the hole. Now, whether you can do this automatically with your software combo, I don't know. Worse case: load your drawing into your cad system, and manually plot points in the center of all the hole locations.

This can be done in the same dxf file as the milling toolpath, and that way, everything should stay in register. By using a different layer for the points, you can then blank everything but the points and you should be able to call up some kind of automated drilling cycle in Mach2. Someone else familiar with Mach2 may be able to chip in with comments on how to continue from there.

Thanks. Had my brain stuck. I couldn't stop thinking "raster to vector", and you can't vectorize a single pixel. Anything more than 1 pixel and you get a X or Y move and snap the drill bit. Your suggestion looks like it'll work well. I'll certainly give it a go. Cheers.

Regards Terry.....
http://www.terry-is.f2s.com

[fyffe555]

Terry,

Check the authors website again. I'm pretty sure he'd included a Gerber zip for the board layout which inclided the gcode for the hole drilling.. I remember being impressed with the detail effort the guy put into it.

[MrBean]

Terry,

Check the authors website again. I'm pretty sure he'd included a Gerber zip for the board layout which inclided the gcode for the hole drilling.. I remember being impressed with the detail effort the guy put into it.

Yes, he does have gerber files for download, which I downloaded. However I have no software that can use it. I know Kcam can do gerber to Gcode. I tried the demo but was not too impressed. I'll keep my money and find another way.
Hu's idea looks promising.

Thanks for the suggestion though. Keep 'em comming..

Regards Terry.....
http://www.terry-is.f2s.com

[santiniuk]

Great to see some video Terry, thats exactly what I aim to build in the short term. I noticed that Mach2 is popular on here. Would you recommend it ?

How long does it take to mill a complete board ?

Cheers

[MrBean]

Hi. I love Mach2, it's been great for me. It seemed overwhelming at first. So many buttons. The people here helped out when I needed it, and I've been getting on well with it ever since. Some people will no doubt dissagree with this view, but that's fine. We can't all like the same stuff. It's more than capable of doing anything I plan on doing with it.
I think I may be the weak link in the chain.

The boards took 13 min each. So 39 min for all three. (no drilling yet, working on it though). I don't know what kind of feedrates you can run for this type of stuff, or any other kind of stuff, come to that. I just used a speed where the motors don't vibrate the machine to bits due to the resonating steppers. Damn crappy drivers. Can't wait to get the PICStep's built and running.

Regards Terry.....
http://www.terry-is.f2s.com

[fyffe555]

Terry,

I think you may be able to do it without any more software - well apart from an editor maybe.. The gerber zip I've just downloaded does include two files with a .cnc extension. If you open them with notepad they are almost a gcode file that turbocnc or whatever could run directly.

The file 'micro_stepper.pcb.output_plated-drill.cnc' contains the t0xx statements and drill sizes and then the X Y statement for position of the holes with that drill size.

It doesn't include the G01 or whatever or a Z** but you could edit those in.

Also the standards used by gerber are different and so the expression X*****Y****** doesn't have a period (.) in there so that they read X016250Y026700 instead of X01.6250Y02.6700.

It's probably worth geting out a ruler and checking that some of those locations are where you'd expect them to be on the board and maybe a quick bit of editing or spreadsheeting might work out..

Another thought is that the gerber cnc format is the same as produced by eagle - if the designer used eagle then it's easy to produce a drill file that turbocnc or mach2 will run directly..

I've been working other pcbs from the opposite direction, I put them together using eagle and run the scripts and programs provided to put out the necessary Gcode for outline, drilling and isolation milling but the last i haven't got to work to my satisfaction, so now I etch that bit and cnc drill/mill the rest.

hope that helps

ttfn

[MrBean]

Nice work. That's definately another one to look into. Carry on like this and we'll have 15 ways to skin the same cat. At least you can never have too many options to choose from, the more the better.
I don't know what software the author used. I don't want to bug him for more files. If he has Eagle (.brd) files and wanted to share them, I'm sure they'd be available for download from his site.

Thanks for the suggestions. I'll CNC drill one of those boards if it kills me.

Regards Terry.....
http://www.terry-is.f2s.com

[MrBean]

here's a close up shot of the isolation channels.


Regards Terry.....
http://www.terry-is.f2s.com