Hi Folks,
I searched for this issue but didn’t find a good match.
I have a 4 layer board that I want to check the routing on, it’s been done by someone else so I just have the Gerbers.
When I look at the top copper layer it looks OK
but when I go to print it and look at a print preview it looks quite different
Is this something I am doing wrong or a possible bug ?
cheers
Please post your KiCAD version from Help>About>Copy KiCad version and if you don’t mind sharing those Gerbers maybe you could post them here, for others to look at them, if it is not possible, at least make an screenshot of your print dialog and the options that you selected.
It looks like a bug if the view in Gerbview looks so different from a printed version. Posting the gerber files would help.
Is there any difference you can see on the gerber files between the features that do and do not print?
You can also:
Gerbview / File / Export to Pcbnew and then print with Pcbnew.
I also spot 2 errors right away.
The measurements should not be on the gerber files at all. I also see the outline of the PCB, and that outline should not be on a copper layer, but only be on a separate gerber layer.
Only put on a copper gerber layer what you want to become actual copper, and nothing else.
My KiCAD version is 5.1.8 -1
Sorry I can’t post the Gerbers as they are proprietary and not mine to post. Will post the print dialogue options a little later.
Pretty sure the issue is with the non representation of Negative Objects in the print output
Not 100% sure which Print Dialogue you want to see ?
Yes, the parts that do not print are Negative Objects, see my post above.
I am not familiar with “negative” features on Gerber files (don’t know much about Gerber at all, just the basics).
As far as I know Gerbview works very nicely with Gerbers generated by KiCad, but KiCad probably does not use those “negative features”.
My common sense tells me that the printout should look the same as in Gerview itself, so this sure does look like a bug in KiCad.
As far as I know KiCad developers are very keen on squashing any bug in KiCad, and a test file to reproduce a bug is a big step in improving the software.
I understand you want to be careful with the files of your customer. and the simplest solution is to just use another viewer.
If you want to help improving KiCad, there are a few simple things you can consider:
Also:
Do you know with which software those gerbers were generated?
If you do, then maybe another KiCad user with access to that software can make a test file.
A negative object is subtracted from a normal positive object. KiCad doesn’t use negatives when it creates gerbers. I’m not surprised if there’s a bug in printing them.
I do of course know what a negative is.
KiCad uses them in footprints internally for the solder mask and solder stencil layers, but those do not make it to the Gerbers as far as I know.
Me too 
I just selected the top layer, very simple, nothing complicated.
Yes, Solidworks PCB, which I believe is based on Altium
I might have something simple I can share that exhibits the same issue. Will have a look.
Of course you know what a negative is, but it has a specific meaning in gerber files. A gerber graphic object is marked as negative and subtracted from another object. KiCad doesn’t use such objects in the board file format or the footprint file format, nor does it use such objects in the generated gerbers AFAIK. The “negative” mask layer is a different thing, it’s about interpretation WRT external world, not about file formats.
This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.
