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geekhack Projects => Making Stuff Together! => Topic started by: kit.caps on Fri, 24 July 2020, 02:42:08

Title: Help with 3D resin printing spacebars
Post by: kit.caps on Fri, 24 July 2020, 02:42:08
I've been trying to design a 6.25u spacebar and have been resin printing them. I've designed the stem insert(idk what to call em) to the best of my ability and after starting from scratch a dozen times, I don't know how to fix them anymore.


This is how the they look: https://imgur.com/a/Q5ABD7L


My problem is that the spacebar doesn't really "stabilize" on cherry stabilizers: https://imgur.com/a/U5tWZTQ


The stems come out fine, I can even say that the 2 outer stems have more "grip" for this print: https://imgur.com/a/kAttOE9


A potential issue that I'm thinking of is that the stem insert thing is too long, there's still a gap above when you insert a switch on it(https://imgur.com/a/D6LUXY9), but the spacebar works perfectly fine on the stabilizers with the wire on top of the pcb.



Sorry if my formatting is bad this is my first post and I've ran out of ideas. Thanks in advance :)

edit: Thank you for all of the advice! I will be testing them out and only print the + to do some test fitting for the stabs. I will come back for updates.
Title: Re: Help with 3D resin printing spacebars
Post by: yui on Fri, 24 July 2020, 04:09:13
going from what i have gleamed online when i was planing on getting an SLA printer i think that resin shrinks when it cures, so that may be part of your problem, or that the resin in the cross is not actually curing properly and allowing the stabs to rotate inside. those 2 options seems the most logical to me, i do not know if it is possible on your printer and if you may did already try but maybe increase the layer curing time?
to be honest i have no experience with it and making this post partly so that it stays on the top a bit longer
Title: Re: Help with 3D resin printing spacebars
Post by: fpazos on Fri, 24 July 2020, 05:03:03
I'm going to say something crazy. Maybe that isn't a problem only of your spacebar, but also from loose stabs. Compare the working of your  standard spacebar with your printed one.

I also believe that you can be right about your stems. You probably can fix it cutting a bit of your stem and see if it makes a difference.

Enviado desde mi Redmi Note 7 mediante Tapatalk

Title: Re: Help with 3D resin printing spacebars
Post by: Leslieann on Fri, 24 July 2020, 06:15:46
Unlike normal caps, stabs require being gripped by the cap in order to function.
If the stems are not gripped tight enough by the spacebar it will simply rock on the switch. Holding a switch is not enough, it needs enough grip to counter the bending of the stab and switch spring.

The other possibility is that the stabs are mounted or assembled improperly, check with a normal spacebar.
Title: Re: Help with 3D resin printing spacebars
Post by: nevin on Fri, 24 July 2020, 07:19:23
i'm with leslieann, if you get this: https://imgur.com/a/U5tWZTQ

the stabilizer is not working as they should. looks like it's pulling off the stab stem on the opposite end of where you're pushing. almost like there is no stabilizer under it.

i don't think length stem length on the spacebar is the issue. it's how tight it holds the stem of the switch/stabilizer that's the issue.

how tight is the fit on the stabilizer stem? you showed a switch, but the stab stem may be a different fit/tolerance
- could try a long sliver of paper or something to try to get a tighter fit
- might be easier to test fit if you had a spare stab or removed the one from your board for testing.

once you get an idea of the difference, just add a tiny bit to the inside + of the spacebar for a tighter stem grip.
- you could print one of the cylinders from the spacebar that goes over the stem until you get a good fit compared to your regular keycaps. focusing on just that one section until you get the numbers right for your setup (file/printer/curing)

looks great by the way! resin is the way to go for caps for sure.
Title: Re: Help with 3D resin printing spacebars
Post by: kit.caps on Fri, 24 July 2020, 15:15:17
i'm with leslieann, if you get this: https://imgur.com/a/U5tWZTQ

the stabilizer is not working as they should. looks like it's pulling off the stab stem on the opposite end of where you're pushing. almost like there is no stabilizer under it.

i don't think length stem length on the spacebar is the issue. it's how tight it holds the stem of the switch/stabilizer that's the issue.

how tight is the fit on the stabilizer stem? you showed a switch, but the stab stem may be a different fit/tolerance
- could try a long sliver of paper or something to try to get a tighter fit
- might be easier to test fit if you had a spare stab or removed the one from your board for testing.

once you get an idea of the difference, just add a tiny bit to the inside + of the spacebar for a tighter stem grip.
- you could print one of the cylinders from the spacebar that goes over the stem until you get a good fit compared to your regular keycaps. focusing on just that one section until you get the numbers right for your setup (file/printer/curing)

looks great by the way! resin is the way to go for caps for sure.

I think the stabs work fine, here is me using a regular spacebar: https://imgur.com/a/e2AC67n
You're probably right about the fitment of the stem on the stabilizer, it seems it's too loose. I don't have any spare stabilizers to test it out of the keyboard, but I'll just print stems by themselves to test on the ones on my keyboard(it is a prebuilt and I don't have any experience underneath the keeb). Thanks for the advice everyone!
Title: Re: Help with 3D resin printing spacebars
Post by: nevin on Fri, 24 July 2020, 15:21:39
sounds like a plan. you'll get it fine tuned pretty quickly once you start making adjustments.
Title: Re: Help with 3D resin printing spacebars
Post by: Leslieann on Fri, 24 July 2020, 21:44:27
An old trick with loose caps is to use scotch tape.
Place a small piece over the stem and push the cap down over it, repeat with more layers until it's tight.


I agree with Nevin, looks good and resin is definitely the way to go for caps.