pcb-gcode. how to remove all copper other then traces

[disonance]

Hi guys,

i'm new to Eagle and PCB-gcode. Been trying various settings but cant seem to get it right.

How do i Remove all the copper on the copper board, other then the TRaces that i want.

any ideas..?

thanks

[mcphill]

Is there a specific reason you want to remove it all? You really just need to isolate the traces... Having the extra copper on board can often be of an aid in cooling.

That said, you won't be able to do what you want in one step (well, not efficiently), but you can do it in a couple steps.

First choose a large cutter (1/8") for your router (I would not try this with a Dremel, not enough HP) - I use a variable speed Bosch Colt router. RUN pcb-gcode-setup.ulp in Eagle, and under Board, Isolation, pick 0.125 for Default, 0.5 for Maximum, and .0625 for step size.

What this does is insure there is 0.125 space between traces (the size of your bit), will machine it out to 0.5" (you may be able to go larger, but there is a limit - it won't do 1"), and will step over 0.0625" from one area to the next. This should be a pretty efficient way to take out large spaces of "waste" copper. If you don't have a lot of areas with 0.125"+ open space, you can either skip this step, or use a smaller tool.

Next change to a smaller bit, say 1/16". This time choose:

0.0625 for Default (diameter of the bit)
0.125 for Maximum (2x bit diameter)
0.0313 for step size (0.5x bit diameter)

This should make a max of two passes, and should clear out some areas that the larger tool could not reach. If it leaves some "islands" you may need to increase the Maximum up to 3x bit diameter.

Finally, change to a smaller bit if you have to, depends on your trace size and spacing. I like 0.0156" snub nose end mills. Use these settings:

0.0156 for Default
0.0313 for Maximum
0.008 for step size

This should do the final sharp edge clean up and split apart tight traces - anything at least 0.016" apart. If you have traces tighter than 0.016", you will need to go to a V-bit and play with smaller Default diameters and also with the depth of cut so that you can "create" the effect of a tiny tool by going to the depth that will machine away less than 0.016".

Also, I suggest you run Opti on the code from PCBGcode, this re-sorts the GCode moving close cuts together more, so it speeds up the machining process. You can download it from PCBGCode.org, which links to here:

http://www.mediafire.com/?sharekey=a...cff8f0ef4e165f

Good luck!

Originally Posted by disonance Hi guys, i'm new to Eagle and PCB-gcode. Been trying various settings but cant seem to get it right. How do i Remove all the copper on the copper board, other then the TRaces that i want. any ideas..? thanks

[disonance]

thanks Mcphill,

Thats about the most comprehensive information I've had so far! The search function for the yahoo group site for PCB-Gcode seems to be down and I gave up searching after going thru 10 pages worth of discussions.

I'm milling out an Antenna trace and some RF power lines, so i really need to clear off all the copper on the top plane.

Thanks for the info!

[mcphill]

Ah, that makes more sense. There are times when the copper will be a problem, and antennae fit that category!

As for the Yahoo! site, I think it is now "obsolete". The new phorum (their spelling, not mine) is at www.pcbgcode.org, though it appears that participation levels there are very low. The history on Yahoo! is rich, but like you, I have had problems searching it...

A few corrections/clarifications to what I posted:

On each step, you do need to tell PCBGCode what diameter tool you are using, this is in the second tab in the setup, under "Machine". At the bottom left, enter the tool diameter under "Etching Tool Size". Also, if you want to keep clear of the trace edges on your "rough" cuts, add .005-.010" (or more if you want) to the tool diameter in this setting. The software will "think" that the tool is 0.135" in diameter, for instance, but cut with the actual 0.125". This will leave your traces 0.005" thicker than the end result, and allow a smaller, finer tool to make the final cuts on the trace edges. The stepover will take care of the material left in the middle of an "open field" of copper.

Also, obviously (?) the numbers I posted are "starting points"/suggestions. You will likely need to play around to get them to work.

Finally, where I said it would take a maximum of two passes, it could well take three. One at "0" stepover, a second at "1" stepover (1/2 tool diameter), and a third at "2" stepovers (full tool diameter).

Mike

Originally Posted by disonance thanks mcphill, Thats about the most comprehensive information I've had so far! The search function for the yahoo group site for PCB-Gcode seems to be down and I gave up searching after going thru 10 pages worth of discussions. I'm milling out an Antenna trace and some RF power lines, so i really need to clear off all the copper on the top plane. Thanks for the info!

[pminmo]

There is a simple analysis on my website on how pcbGcode settings affect isolation paths: http://millpcbs.com/index.php?option...d=10&Itemid=44

[harryn]

There is potentially another approach that might work for you.

I have seen some articles where people would use a black sharpie marker as "resist". Maybe you could put a sharpie on your router and first trace out the areas where you want to keep copper and etch away the bulk portion. The final precision traces could be machined.

My understanding is that the copper needs to be very clean and not scratched for this to work, so the Author had used polishing compound to remove the surface oxide (warned against sand paper) then did a final degrease and clean up prior to the marker work.

[medvampire]

Spray your board with liquid tape.
Mill around your traces pull the tape off the board where you want to remove the copper.
Use chem process to remove the excess copper..It also cleans up rough edeges from the milling as well.
Steve

[pminmo]

You can use different cutters of different widths and run pcb g-code with two setups. i.e. a Vbit to do the fine stuff then a 25 and larger end mill to do the crearing passes. The larger setup with pcb g-code won't run passes through areas that width won't do.