PCB milling

[Ubarch]

Hello,

I know this must have been asked before, but the search terms are so ambiguous that I can't find anything useful. Is is possible/difficult to make a benchtop CNC mill perform as a PCB router? Here are the circumstances surrounding my question:

1.) I'm trying to finish my thesis, and this requires some circuit fabrication that I would rather no complete with wire-wrap. I don't have the money for proper fabrication services (4-layer boards, solder mask, silkscreening, etc. runs about $180 a shot). I'm pretty good with Eagle CAD, and this can produce Gerber files, and some other formats.

2.) My company bought a Microproto DSLS 3000, and it's sitting in a lab, all set up, waiting for someone to learn to use it. We bought it right at the end of the fiscal year, and when everyone switched over to new tasks, nobody was able to give it the kind of serious time needed to make it useful.

3.) I have regular access to this device, and have some time to experiment with it.


Has anyone done this before? What kind of pitch can you get out of these things?

Thanks!

[Bubba]

Ubarch,
There is an ulp file written by J. Johnson that will generate the necessary gcode file to run.

You can find it in cadsoft users directory, his yahoo group, or his forum at http://pcbgcode.org/index.php

Others have also done file optimization to make the gcode more compact and faster.

[Jeff-Birt]

I use Eagle + PCBGcode + Mach3 + Taig CNC to make prototype boards. The limiting factor on a machine like a Tiag is the spindle speed. For PCB isolation routing you want to feed 0.001" per RPM. Since the Taig has a 10K RPM limit that works out to a feed of 10 IPM. It works well but is slow.

To get the best quality boards you need to adjust the machine to reduce backlash as much as possible and you need to surface a mounting board (to mount PCB on while routing) with the same mill to insure a mounting surface that is normal to the spindle.

The hardest part for me starting out milling boards a few years ago, was knowing what bits to get. I came up with some 'Starter Kits' that have the most common sizes of drills and two 60 degree 'V' tip isolation bits. (The 'A' kit is geared toward through hole and the 'B' kit is geared toward surface mount.)

You can see them here: http://cnczone.com/shop/Precise_Bits_86618.aspx. The V bits and drills are available separately too.

[SScnc]

Originally Posted by Jeff-Birt I use Eagle + PCBGcode + Mach3 + Taig CNC to make prototype boards. The limiting factor on a machine like a Tiag is the spindle speed.

I do the same, except using an X2 with a high speed spindle adapter and a Rotozip spinning at 30,000 rpm. Works great.

Allot of help and info on the PCBGcode can be found here, like Bubba said.

This process is not nearly as hard as it may seem at first, in fact it's very easy.

[tooManyHobbies]

Originally Posted by Ubarch 1.) I'm trying to finish my thesis, and this requires some circuit fabrication that I would rather no complete with wire-wrap. I don't have the money for proper fabrication services (4-layer boards, solder mask, silkscreening, etc. runs about $180 a shot). I'm pretty good with Eagle CAD, and this can produce Gerber files, and some other formats.

Before you give up on the PCB fab route (no pun intended), have you looked at http://www.batchpcb.com/?

I've used them & they are very good. The only limiting factor was the turn-around time, but after looking at the latest news on their web site, it looks like they've improved that too.

I will admit that once I get my X2 CNC'd, milling PCB's will be one of the priorities for me!

tom

[SScnc]

Originally Posted by tooManyHobbies Before you give up on the PCB fab route (no pun intended), have you looked at http://www.batchpcb.com/?

Or this outfit seems pretty good too. I've been checking with them to make allot of PCB's based on a proof PCB milled on my X2. Pricing seems very good to me.

Steve

[Ubarch]

I tried batchPCB, and the turnaround time was just too great for me. If I pay for PCBs, I like to go with 4PCB.com; the quality is good, you get the PCBs in the time you paid for, there are some student specials, and they have an online DRC service that I like.