A small demo to show how I test fit footprints.
It’s a combination of a few things to make it work perfectly.
The first step is to print a PCB mirrored on a piece of Paper:
PcbNew → File → Print → Options Mirror → Print.
2nd step: Take a needle and pre-punch all the mounting holes into the paper.
(For the large holes I used a hole punch).
3rd step: Carefully put the connector into the sheet of paper.
4th step: Take a picture or scan the whole contraption with a flatbed scanner.
This makes it easier to see small deviations than with the naked eye.
If you also put a ruler into the picture you can use that (or the known distance between 2 pins) to calculate corrections for the next iteration.
The trick is to print the mirror image. This will ensure that you can take a picture of the connector pins and the PCB layout in the same picture. See below.
Please be a bit polite to each other.
This little tip obviously was not meant for the guru’s with an in house fab but more for the hobbyist who is anxious to get his first PCB outsourced and has to wait a month for shipping because he’s not willing to pay the fee for same day delivery.
@bobc:
If you ever get around printing a PCB for test fitting connectors I’d like to see a picture of that here. Maybe even add a little tutorial of how you get the data from KiCad to your 3d printer?
I don’t have a 3d printer, but I’m betting on getting a mini CNC milling machine going within a few months
I think the main problem would be that it’s difficult to get the resolution for small holes, so those would probably need some clean up. I have code to convert VRML to STL, so I might adapt that.
It is not necessary to have a 3d printer, there are 3d printing services, but obviously not as convenient as in-house. I have also got a small CNC, but don’t have a good place to use it, so it gathers dust.
For cutting flat sheets, a laser cutter might be better, that’s a whole other thing…
Kicad Stepup (freecad extension) should do the trick. (or direct idf export.)
Maybe reduce the board thickness settings in kicad. You don’t need 1.6mm material thickness for this application. 0.5mm should be enough. (Kicad stepup uses this setting to define how thick the board body will be.)
From freecad you can then export a stl file which should be usable by 3d printers. (As i remember 3d printer slicers use stl files as input. If they could use step, that would be even better.)
The printed image has to come out at a fairly accurate 1:1 scale. Between the rendering to a *.pdf document, then printing a hard-copy on a home or office printer, accurate scaling is not guaranteed . You may have to play with printer settings to get accurate 1:1 scaling.
Yes, I think a well calibrated laser printer would outperform a 3D printer, certainly the cheaper FDM ones. SLS or resin might be better, but those are expensive. At work we use an SLS printer for creating space models of enclosures and assembled PCBs.
It is a very nice way to test footprints. I always make a print and test it this way before production. Works also very well with smd parts. Especially with smd parts you can quickly mess up if you selected the wrong footprint for it. (especially the wide vs narrow footprint versions are killing).
With through hole pay attention to the drill / hole size as well!
Set the print settings to ‘Real drill’ in kicad:
Would be a shame when the holes are too small for the part