JLC 3D Printing

[PeterCLarsen]

I really like the look of your keyboard so I ordered PCBs and case through JLCPCB.

The PCBs are already on their way, but they said parts of the case were too thin to be able to guarantee they would not break during transit, or shortly after arrival.

They recommended the thickness be increased to 1 - 1.5 mm. I have never worked with STLs, but I saw your discussion with kovasap about case tolerance (#3) where you pointed him to a spot in the config file where he could adjust the tolerances. I was hoping you could point me in a similar direction so I can increase the thickness of the plates.

Thanks
PCL

[ctranstrum]

Hey, thanks for your kind words about the keyboard.

I have printed these case files three separate times in Imagine Black resin from JLC, and every time they warned me about the thickness. On one of the prints, I noticed that there was a little warping right above the xiao on the top of the case, and on another there was slightly more noticeable warping immediately below the battery on the bottom case, which while not that bad, is not visible during normal use and so even less of a concern. In other prints, these areas came out clean.

So yes, they have to warn you about them, but from a sample size of the three I printed, I never had a problem that I considered to be bad enough to want to re-print. However, I eventually bought a 3D printer and printed them in PLA myself, and had zero issues with that.

If you are very detail-oriented and these things bother you, but still want to try to print as-is at JLC, then I would suggest printing in FDM instead of resin, since these usually come out a bit better, though I never tried that at JLC myself.

All that said, it is indeed possible to put in a little extra work and update the case files if you really dislike the idea of printing at JLC with warnings.

You can increase the size of the bottom case in the config file, and it will just print a bit thicker overall, which will add some height to the keyboard. However, you can't easily increase the overall thickness of the top case, since it also operates as the top plate for the switches, and its thickness needs to be fairly precise.

The basic layout of the bottom case is in the config.yaml file, starting at line 750. You should be able to simply increase the extrude value on line 753, and then increase the shift values of every other portion of the bottom case segment, as well as those in the bottom_left and bottom_right_reverse cases to match the amount increased in the extrude. All the numbers used in the config file are in mm. So if you increase the case by 1mm, you can increase the shift by the same amount. (Raising the height of the case means you need to raise the offset of cutouts that should have their openings at the top of the case.) Double-check the results before you print, obviously.

For the top case, if you want to try to add a bump over the xiao without increasing the thickness of the rest of the top case, you could try that, but it would mean you would also need to figure out supports for printing it at home because both the top as well as the bottom side of the top case would have significant areas that would be raised above the print surface (although in theory maybe JLC would handle this for you on their end if you print in resin, which may not have the same constraints as FDM).

Another option for the top case would be simply to remove the section of the case that covers the USB connection of the xiao, since that's where it's thinnest. You can do that by increasing the extrude value of the USB cutout on line 721 to 2.2, which is the height of the top case, and then removing the shift values on line 722 (just delete the line).

If you know the actual size of your battery and don't need extra wiggle room (many batteries are slightly larger than their stated dimensions) you could also try to minimize the size of the cutout there (lines 730-734 for the top case and 764-768 for the bottom case). If doing that alone eliminates the warnings, then maybe you wouldn't need to increase the thickness of the bottom case at all.

Let me know what you decide to do and how it turns out, and feel free to ask if you have any other followup questions.

[ctranstrum]

See also the discussion on issue #9