etching boards with router

[dowis]

Anyone given this a shot? One of my friends just received a very nice CNC Router recently and is spending a lot of time playing around with it. I'm turning an adapter in the morning for him to use dremel sized bits in the standard collet of the router. We were talking about boards for a project that he is working on and he mentioned that he will be etching his using the router. Any ideas on this? I would assume with a tight enough tolerence window on the z axis and the proper cutter this should be possible. Would be a lot of copper clearing on some boards. And seems to me to be a lot of programming. But, it is his hobby and he has the time. I'm going to order some copper clad and let him give it a go. Thoughts? Opinions? :?:

[Dielectric]

Pretty common, actually. If you use Eagle, there are programs to convert the PCB layout information to GCode for the CNC controller. I think I've seen Gerber to GCode converters, too. Usually they do "isolation" routing where only the traces are carved out, the copper in between is left behind. The best results I've seen come from a small cone-shaped cutter, and by allowing generous trace/space rules.

[bobkeyes]

I've never done the etching, but I have done a fair amount of drilling and I don't think the etching would be a problem for the machine. However, I think the machine cost might be pretty high if you had several to do. Chemical etching would be cheaper I suspect.

[dowis]

Converting to GCode was my biggest concern. The next biggest was of course some of the finer traces that will be needed between some of the pads. Tim just purchased VCarve Pro and feels very comfortable with the software and its functions. I am not familiar at all with it or its file formats. We will be going over this tomorrow so that I can work on a file format that we can both work with. I believe we're going to start with some SSRs and then go from there. Isolation traces do seem like the most logical approach. I'll have to pass this on.

I'm not familiar with chemical etching at all. Tim(the friend) however, has a home machine that was purchased just for hobby use and has plenty of time and patience(another thing I'm not familiar with;) ). Once the set-up is done and programming is worked out. I believe we could knock out several boards pretty quickly.

[Cheater]

My old uni had a router designed for pcbs.

I never used it due to the boards being more difficult to solder.
The gaps are very narrow and without solder mask the solder can bridge tracks easily.

[ErnieHorning]

I use a CNC router specifically meant for circuit boards. I has an accuracy of 3 mils though it's repeatable to .3 mils. Though I can squeeze down to an 8 mil isolation I try to get at least 20 mil and prefer 30 mils.

It can move up to 60 in/min which is fine of small boards but the more you do, the more likely the bit will wear out or snap off. When I use the full 12 x 18 inch sheet, I only go 30 in/min and run it over night. I think it takes 3-4 hours at that speed.

Typically I just use a pointed bit, I believe 60 degree, for everything even if the isolation width is different on the same board.

Even though it looks better to use an end-mil for rub-outs, I use the same pointed bit.

Go slow and good luck.

[dirknerkle]

WOW, Ernie!

On the photo of what look to be SSRs, I'm curious why you removed so much material instead of just removing a buffer area around all the "live" tracings.

[ErnieHorning]

...I'm curious why you removed so much material instead of just removing a buffer area around all the "live" tracings.

I felt that since these would likely be exposed to the elements the most, there would be less chance of shorting. This was my first run and I had no idea what to expect in the outside environment.

These boards have now been used for four seasons now without any masking and they show nearly no oxidation. I made more SSR's last year and split the copper under the opto's.

[dowis]

Very nice looking boards. Thanks for the comments and suggestions of everyone. Looks like we're going for it.

[dslynx]

Dang.. that does look nice.. makes me think... I wonder what my carvewright could do.

[mel4853]

www.brusselsprout.org/PCB-Routing/ Great sight and has everything you need to get started with your cnc.

Mike

[eroberts]

Ernie, that board looks as much like art as a Renard board.

[bmcgeeny]

I use a CNC router specifically meant for circuit boards. I has an accuracy of 3 mils though it's repeatable to .3 mils. Though I can squeeze down to an 8 mil isolation I try to get at least 20 mil and prefer 30 mils.

It can move up to 60 in/min which is fine of small boards but the more you do, the more likely the bit will wear out or snap off. When I use the full 12 x 18 inch sheet, I only go 30 in/min and run it over night. I think it takes 3-4 hours at that speed.

Typically I just use a pointed bit, I believe 60 degree, for everything even if the isolation width is different on the same board.

Even though it looks better to use an end-mil for rub-outs, I use the same pointed bit.

Go slow and good luck.

I've seen them live and in person and they are really fine detail. Ernie, what software does it run?

[ErnieHorning]

...what software does it run?
I use proprietary software that came with it that accepts standard G-Code. I don't know what the input to the router actually. It connects with RS232 and may accept G-Code directly. I could try it, now that I'm curious too.

[Blackbeard]

Should probably start a new thread, but has anyone ever built a DIY CNC PCB router? I've gotten some interest in them after this thread, but there's a lot to it and just wonder if anyone has a good link to a How-To? There's tons of them out there, but choosing one is much like reading an encyclopedia. They all seem to be authored by mechanical engineers. Guess I'm showing my intelligence level, huh?

steve

[mattrob]

I tried building my own machine last year, but ran out of time. The machine was based on one from Instructables. I just never got the screw drive working quite right, plus I had access to machines at school to cut my boards on. :)