Eagle and Laser cutter

Very interesting approach.

I would like to see an example picture of a finished pcb to see how it compares to mechanical machining/engraving methods.

What kind of trace width and spacing can you achieve?

How fast does it vaporize (mm / minute)?

Maybe a needle-point center-punch would improve drilling accuracy....

Well I haven't really messed with trace thickness since throughout my PCB making I've purposely made the traces as long as I could because I was using the toner transfer method...

But here's some pictures of the first board I have done and messed up

Looks good.

It also looks like you have enough laser accuracy to make the pads a bit bigger and easier to drill. A smaller drill bit might help as well.

I would try to go through the copper with a center punch to provide a drill guide, but might also try a secondary punch to break the copper circles so the drill doesn't tear up the copper.

You could make the second punch with a broken drill bit shaft (with the correct hole diameter) - grind it flat or concave if you can and use it as a punch just to break through the copper layer, or at least define where the copper will get cut.

Another trick is to stick a piece of clear tape on the copper side (or both sides) before drilling - this reinforces the copper you don't want removed and minimizes burrs.

I guess it is too much to ask the laser to burn all the way through the copper so you could skip the etching step?

40W just doesn't seem like it will... Now I am scared to put it at full power though

after a night of poorly reading their code and the better part of this morning hacking together some code, I have managed to modify pcb-gcode to do what i want... It's currently being tested but at least I can go from Eagle to my laser cutter without manually editing the output now

Ill post results a bit later

You said here you are using the Toner transfer method I assume you haven't tried the laser yet then . If that is the Laser then I'm pretty impressed. I would also say stay with vector formats and avoid raster like the plague as although you have enough accuracy you do cannot switch off the beam fast enough for a clean edge as it takes several ms to stop lasing and just messes up the etch resist.

Most of the laser software don't take GCode at least the Chinese variety if you can create a DXF then you can import that into almost all the Software. BTW eagle provided a load of tools to do this but I've not tried as it was windows only..

Good luck ....Do you have a link to the pcb-gcode thing BTW?????

Previously I was using toner transfers to do PCBs. The images posted here are from my first attempt at lasered PCB's (which still need to be etched afterwards anyway )

The original place for the pcb-gcode plugin is pcbgcode.org, which is meant for milling the board using a mechanical cutter.

My modified version can be found https://www.dropbox.com/s/jsx7z02rd623boq/pcb-gcode3.6.2.4-laser.zip  and should have a bunch of warnings attached to it but doesn't

(My cutter is setup to where that spindle on/off turns the laser on/off; the modified code turns the laser on when the Z is negative and off when the Z is positive)

I would dry run any output from this first...

Here's a board from the newer code, its not perfect but my hand drilled holes are a little better since I had better markers...

Perhaps later I can try putting the board back after etching and have the laser cut the holes since theres no copper protecting them now

That's a good result then. I'm sure you can remove the resist at least as accurately as any hope process can remove the underlying copper so you are good there. The laser hole thing may well be a pain as you will need some lugs or some such on the bed to align the board again to get the correct registration. Another issue I find is that the FR4 has a tendency to char, maybe that wont be such an issue for just the holes and after all you will be soldering over them any way

Thanks for the links BTW!

How did you give yourself a "helpful answer" on your reply .... you could make a ton of points by answering your own question ....BUG TIMe ..LOL

Well at least for now it does what I want and now I can move on to more interesting things like building a new controller board for this cutter

It was a cheap 500USD one that came with a crummy proprietary driver board and software, so we've had this scabbed together breakout board to get it to a parallel port to make it usable...

The original idea for using a laser cutter and paint was from these two instructables links, the first one has you cut a temp jig out of acrylic so you can put the board in and the other uses some kind of snap jig. But they are both useless if you happen to turn off your machine lol

Nothing Labs (Rich Olson): 2-Layer Circuit Boards Using Laser Cutter / Chemical Etching

Double-sided PCBs with a laser cutter

But at least this is a getting stuff done season for me and not procrastinating

Are you aware you can get those generic laser cutter controller boards off EBAY that normally already supported in a given set of software... I nearly bought one to repair one of mine!

Then again it's only a spare of a spare so I'm still intending to do something similar to your self ..good luck