Need Help -> Eagle and PCB-Gcode

[keebler303]

Background:

I have been drawing my layouts in cad and generating isolation toolpaths with cam. I have decided to switch over to eagle/pcb-gcode to make it easier to make layouts. Working on my first try now, I'm a newb to both.

Problem:

I am trying to make a single sided board for through hole components. I have a few components layed out and traces between them on the bottom layer. I ran PCB-Gcode to get my toolpaths. The problem is the isolation for the traces is on the bottom as it should be. However, the isolation for the pads of the components are on the top layer. The result is that the traces are not isolated on the bottom layer, which is the only one I am milling.

I can elaborate if this is not clear.

Thanks
Matt

[Jay C]

No it's not clear. Thru-hole pads are on both layers. What do you have your isolation set for on your bottom pour (assuming you are using one since you said isolation)? Can you post your .brd file and gcode file?

[keebler303]

There is no bottom pour on the board. It is called isolation milling, no? I have partially solved the problem, I had a couple traces too close to the pads and I messed with a few of the pcb-gcode setup values to get a single pass toolpath. I manually moved the traces and then it worked properly. I guess my question now would be how to tell eagle to autoroute the traces in such a way that there is enough clearance between pads and traces to let the cutter pass between them (like a minimum clearance between any two objects).

Here is my board file, remove the .txt. The problem was the trace between pad 1 and 2 on "terminal". It was too close to pad 2 and the cutter wouldn't fit. O dragged it out a little and now everything is good to go.

Thanks
Matt

[Jay C]

Here is what I get when I run you design through PCB-Gcode, then through my optimizer to shorten Z-moves.

So, now for some more questions:

• What version of Eagle?
• What version of PCB Gcode?
• What kind of tool? What tool bit width?
• Using Mach?

And some suggestions:

• 16mil is tiny. Try to use bigger traces if possible. Rotate parts, whatever it takes if you are planning on milling these.
• Power wires need to be bigger still to handle the current
• The mill line doesn't have to be that thick. In fact, I haven't had too much success using the milling layer and PCB-Gcode.
• Try to get you wires to join on thru-holes ... it makes the copper less likely to tear by eliminating sharp angles.
• Do you best to have all Grounds come to one point (star)

FWIW,
Jay

[keebler303]

Jay

The G-code you posted is similar to mine. I have reduced mine to 1 pass around, not two. I don't think it is necessary for most circuits and doubles the milling time.

Answers:

• Latest version of eagle, downloaded and installed last night.
• Same with PCB-Gcode.
• I have an 1/8 inch Carbide Half Round I have been using. The tip is pretty sharp, probably around .01".
• Yes Mach, newest lockdown version.

Responses:

• 16 mil is the default. I am not planning to mill these boards as is. I just copied a circuit I have recently used to learn the software.
• Agreed.
• John, the author of PCB-Gcode, recommends using a mill line the same thickness as your cutter (1/8 EM for me). PCB-Gcode doesn't yet support offsets for different size milling cutters so if you make that line the same width as your cutter, you can visualize where it is going to cut and avoid trimming off any parts not meant to be trimmed. I have looked at this in the gcode and it appears the toolpath follows the centerline of the mill line.
• Agreed, I always did that when doing this manually, as well as making all corners 45 degrees at most but the autorouter doesn't do it for some reason? Maybe I don't have it setup correctly?
• Not really important for this particular circuit but definitely for best practices.

Do you know how to optimize the autorouter? I would like it to do some of the things mentioned above automatically, if possible.

Thanks for your time
Matt

[Jay C]

Originally Posted by keebler303 Jay The G-code you posted is similar to mine. I have reduced mine to 1 pass around, not two. I don't think it is necessary for most circuits and doubles the milling time. Answers: Latest version of eagle, downloaded and installed last night. Same with PCB-Gcode. I have an 1/8 inch Carbide Half Round I have been using. The tip is pretty sharp, probably around .01". Yes Mach, newest lockdown version.

My tool tip is 5mill that's why 2 passes on my settings. At 10 mil 1 pass is fine.

Responses: 16 mil is the default. I am not planning to mill these boards as is. I just copied a circuit I have recently used to learn the software. Agreed. John, the author of PCB-Gcode, recommends using a mill line the same thickness as your cutter (1/8 EM for me). PCB-Gcode doesn't yet support offsets for different size milling cutters so if you make that line the same width as your cutter, you can visualize where it is going to cut and avoid trimming off any parts not meant to be trimmed. I have looked at this in the gcode and it appears the toolpath follows the centerline of the mill line. Agreed, I always did that when doing this manually, as well as making all corners 45 degrees at most but the autorouter doesn't do it for some reason? Maybe I don't have it setup correctly? Not really important for this particular circuit but definitely for best practices.

Ah, well I supposed I missed that point about the mill size I've been opening the Gcode in Cam Bam and running a 1/8" cutter around the outside

Do you know how to optimize the autorouter? I would like it to do some of the things mentioned above automatically, if possible. Thanks for your time Matt

I don't use the auto-router much, but your Routing Grid (when you click the Autorouter button) should be set to 50mil. What is your Bottom layer set to "-"? I like to lay my own tracks. I've found through testing that my machine runs faster/better with straight lines versus 45 degree ones. I also have an easier time soldering if the wire is close to the pad size

Jay

[keebler303]

Originally Posted by Jay C I don't use the auto-router much, but your Routing Grid (when you click the Autorouter button) should be set to 50mil. It is. What is your Bottom layer set to "-"? No, "|". I like to lay my own tracks. If doing a board only, I agree. But if you already have the schematic, its just too tempting to click that little button and see what happens. I still think its easier to go back and edit the autoroutes than from scratch, unless its dead simple. I also have an easier time soldering if the wire is close to the pad size By wire you mean trace? I don't really feel like it matters too much to me. Jay

Matt

[jp_dt]

I'll second the motion to just do single pass on the isolation routing. I set that by making the isolation smaller than the step size in the setup. I've been doing it that way for a while now on layouts that use 0603 smt parts and it works really well. I found that two passes left more copper whiskers to clean up where as single pass left almost none. I'm using the thinktink bits so I'd presume that could change with differing bits.

I might also suggest that you just do the traces on the component side. It'll save you the time and the work of making a fixture that will accurately let you flip and cut the bottom side. And you can use cheaper single sided boards.

As for spacing, if you run the DRC tool, and set the minimum spacing to the level you want, it'll tell you if things are too close.

[keebler303]

You can't do traces on the component side for a through hole board, no way to solder the pins, at least on some components. There is no fixture needed as I start with the bottom up and drill from the bottom as well. I am using single sided boards already, the copper is on the bottom. I'll check out the DRC tool thing, haven't looked into it at all. If I have to use a surface mount part, I put the component on the bottom so I can still use a single sided board.

Matt