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Custom part; trouble with copy, rotate and gerber export

Markus B 6 years, 4 months ago


I'm getting closer to sending my board to the Fab so I started to check the Gerber files using ger gEDA's Gerber Viewer ver 2.6.0. On the way I encountered a number of issues.

I have made a small example with my custom made part (a Roving Networks RN-42 bluetooth module b.t.w.). The example file is attached.

Problem 1 : Gerber export - "Copper0 file export failure(3)"
Problem 1Starting with a blank PCB, I drag the part onto it. When I choose to export the Gerber files from Fritzing I get an error message "Copper0 file export failure(3)". My surface mounted part is without the cooper0 layer and the parts editors gives me a warning about it. Still I expected the gerber export to work. And it does, but only if I add e.g. a smd resistor part to the copper0-layer so it the layer is not empty. Then the error message goes away and I get all Gerber files which also looks ok in the gEDA viewer.

I have also tried with adding an empty copper0 layer to the part - dosn't remove the error message.

Why does a missing copper0 layer in my part generate "Copper0 file export failure(3)" just because I havn't yet added some other part to the copper0 layer?

Problem 2Problem 2 : Gerber export of copied part
Now, if I copy my part on the PCB and export gerber files again, there will be some inconsistency. My custom part svg-image contain a rectangle with no fill and no stroke on the silkscreen layer (only to help alginment when created it in Inkscape I think).  In Fritzing all looks good, but the Gerber output is strange. The svg-rectangle is  "invisible", as expected, in Fritzing but is suddenly rendered only on the copied part (Part 2)!

Why does the copied part create a different gerber output than the original?

Problem 3 : Rotated part results in bad gerber output
If my part is rotated on the PCB, all pads on that part will not be properly reszied in the gerber output. The pads is exactly 1,3 x 0,8mm in the parts SVG file. That can also be verified by measuring the pad size on the non-rotated part (Part 1) in gEDA viewer.

However, notice that the solder mask on some pads on the rotated part (Part 2) seems wrong. It appears as if these pads are not scaled precisely since they are e.g. ~1,295 x 0,813mm measured in gEDA viewer.

Open the picture in a separate window to get full size - it make it more clear.

I'm not sure how big impact this will have on the produced PCB, still it indicates something is not as it should with the export.

Why isn't the soldermask looking the same for all pads when my part is rotated?





Here is the example file


If I'm not missing anything here, let me know if I should add it to the issue tracker.



Markus B 6 years, 4 months ago

Ps. All images are larger if opened in a separate window! Ds.

Jonathan Cohen 6 years, 4 months ago

Hi Markus,

Nice looking post. Thanks for taking the trouble to make things clear.

1. This is a badly worded warning (which I have just changed), and which you can ignore. For most Fritzing users, having nothing on the copper0 layer would be an indication of a problem.

2.  There's been some tinkering with the gerber export code in the latest (unreleased) version, so now in test.fzz, both the inner and outer silkscreen rectangles are rendered for both copies of the part.

3. Confirming the soldermask rotation bug.

This is a sufficient bug report, though if you want to go straight to the issue tracker next time, it will save me some copy-and-paste work.

- j

Markus B 6 years, 4 months ago

Hi Jonathan,

1) Thanks, 2) Thanks and 3 Thanks :-) GREAT support!

Regarding issue 2; if both inner and outer silkscreen rectangles will be rendered in the gerber output I assume they will also be rendered in Fritzing PCB view.

Regarding issue 3; note that not only the soldermask is distorted but also the pad size on the copper layer (not much but still).


Nice piece of software - keep up the good work!

Jonathan Cohen 6 years, 4 months ago

2. The silkscreen should be consistent, one way or another

3. The pad sizes look accurate to me, either as a result of the above tinkering, or--at least in the case of my Gerber viewer--it doesn't display things accurately until you zoom in.

- j