Help on how to 3d print these

[uqs]

Hi there, I'm trying to get these printed on an FDM printer with a 0.4mm nozzle, but I'm running into various issues.

Because the stem is slightly offset (why?) I'd need to turn on supports, but these then are hard to remove again and they are not needed for the bridging on the top anyway (and I haven't found a way to stop all supports at a certain z-height (yet).

Printing them upside-down avoids that issue, but then the top-side comes out ugly (with supports).

The stem is pretty thin/fragile anyway with such a setup, do you recommend a resin printer for these?

I've also tried extending the stem down to the build plate, but this also doesn't work without supports, as it starts with the 4 tiny corners and they don't hold on to the build plate.

The last issue can probably be fixed by adding 4 spans at z=0 that connect the stem corners to the side of the cap and can be snipped at way after the print is done. wdyt?

[julowe]

I've had good results printing the Chicago Steno keycaps vertically, with supports only for the stems. Just let the wall/underside of the keycap (which would be facing away from you when the keycap is on a keyboard) be a bridge and sag a little, it's unseen and at least on my printer (Ender 3, no real upgrades, 0.4mm nozzle), doesn't sag anywhere near enough to hit the keyswitch body when pressed down. And because pictures are easier than lots of words, see attached pictures below from my slicing program (prusaSlicer) to see what I mean. If you're unfamiliar with Slicer, the small transparent boxes are the support enforcers and supports are only generated for those parts. Also, printing them like this make the sliced layers perpendicular to the stem-keycap attachment point and thus stronger/less likely to snap off at that point.

Someone else somewhere said they have had success printing keycaps at a slight angle. I haven't done it, but for reference I attached a screenshot of the keycap angled 30 degrees like they said they did. Seems like it woudl work fine to me, have printed other fiddly objects (28mm mini figs) like this at angles and they printed well and were sturdy. This orientation might be better if you are printing taller keycaps (vs the choc chicago steno) and play with angles or some more selective supports (back keycap wall?)

Unsliced vertical orientation

Sliced Vertical

30 Degree rotation sliced

[uqs]

Thanks for the comments. I'm looking into printing the DES MX caps, so I could get away without supports and that's what I tried. For choc stems you need to get more creative indeed.

What I did so far is to first fix the models, as they were not sitting flush and I didn't immediately notice it in the slicer also, leading to some failed attempts. The fix is here: uqs@8228775

Then I extended the MX stem all the way down (just .25mm more, no biggy), and increased its diameter, so that it would allow the slicer to put an unbroken circle all the way around it. If not for that, the thin parts of the stem would be printed in weird ways.

Finally, I had to add custom bridges/supports from outer shell to the stem to improve adhesion. These can easily be snipped off with pliers after the print. With all those fixes, they print w/o failure all the time (but use adaptive layer heights): uqs@1c63163

Now there's 1 problem remaining. All of them come out great, except for R3, which is a major bummer. There is stringing going on, leaving the surface everything but smooth. I think this is not an issue for anything but R3, as those all slope to one side. But R3 is symmetrical, so it is a bowl shape and that leaves string marks on top, just where you'd like to put your finger. Sigh.

Can you spot the R3s here?

[Emburglar]

Do you have stls to this? Im having a hard time with openscad.....:/

[julowe]

Not sure who you are replying to/which keycaps you want - probably the DES MX caps immediately preceding - but just in case it's the steno chocs I have some STLs in my dev mess branch of the forked repo I think that is all the rows for... well I was going to say a keyboard, but maybe just for my gergoplex. Let me know if there are STLs/rows missing

[seltzered]

@uqs "For choc stems you need to get more creative indeed." thanks for mentioning this. I'm thinking of building my first keyboard with choc switches ( https://www.reddit.com/r/ErgoMechKeyboards/comments/x6mbjh/seeking_design_feedback_atreusinspired_extended/ ) inspired by the 'philadelphia minimalist' caps and starting think it makes more sense to either make resin caps ( https://kbd.news/Homemade-keycaps-1643.html goes into this ) or possibly do some hybrid of adding moulding on top of chopped keycaps.

[MrMarble]

@Emburglar a bit late, but you have some stls here https://www.printables.com/model/865075-des-keycaps-for-keyboard-cherry-mx-version/files