geekhack

geekhack Projects => Making Stuff Together! => Topic started by: ishtob on Mon, 24 June 2013, 23:30:36

Title: new DIY keycap casting thread
Post by: ishtob on Mon, 24 June 2013, 23:30:36: old thread:

http://geekhack.org/index.php?topic=23722.0 (http://geekhack.org/index.php?topic=23722.0)

====================================

So I figured to start a new thread on this topic since its been so long. I've also seen a few other try doing some DIY caps.

I will be updating this regularly as I test out new mixes.

using 2 molds of a modified DSA cap, I was able to make an entire set of thick DSA for my DOXish

(http://i6.photobucket.com/albums/y222/icbob/DIY/MYOC/null_zps06569829.jpg) (http://s6.photobucket.com/user/icbob/media/DIY/MYOC/null_zps06569829.jpg.html)

Materials for casting:
TASK2
Crystal clear

Materials for dye:

Post curing:

TASK2 and other high strength urethanes gets improved strength. The instruction says to let the item cure for 60 min at room temperatures first, than heat it to 150 degrees for 4 hours to improve thermal resistance and strength

what I've found is given the small size of keycaps, whatever reaction needed for the curing process does not occur as quickly as advertised, if you follow this post-cure instruction you will end up with warping and bubbling. I waited 24 hours before I headed the keys.

(http://i6.photobucket.com/albums/y222/icbob/DIY/MYOC/null_zps93c25d90.jpg) (http://s6.photobucket.com/user/icbob/media/DIY/MYOC/null_zps93c25d90.jpg.html)

I'm hoping those who are doing this would be able to share their successes and tips that may help others who wish to attempt this succeed.

and please note, I do not support casting and copying other people's designs, please, original works only unless they are for you own personal use.
Title: Re: new DIY keycap casting thread
Post by: TheFlyingRaccoon on Mon, 24 June 2013, 23:37:22: This is looking awesome so far :cool:
Title: Re: new DIY keycap casting thread
Post by: calavera on Mon, 24 June 2013, 23:42:00: Any estimate as to how much it cost per key cap at that stage?
Title: Re: new DIY keycap casting thread
Post by: ishtob on Mon, 24 June 2013, 23:51:37: its dirt cheap in terms of material... i still got 50% of the resin left, but the cure time and also cleaning up the flashing, inspecting and sanding that takes up a lot of time. It took me almost a week to complete this set of DSA

*material-wise if you don't include the cost of the silicone for the mold, I've spent about $50, so that means the above set costs about $25 plus a couple hundred hours of work
Title: Re: new DIY keycap casting thread
Post by: kenmai9 on Mon, 24 June 2013, 23:54:03: Can you make other colors besides that grey?
Title: Re: new DIY keycap casting thread
Post by: ishtob on Mon, 24 June 2013, 23:55:48: yes I can, I just got a pack of pigment samples from the advanced materials shop, kinda messed up my molds by accident this weekend, will try it out as soon as I get new molds done
Title: Re: new DIY keycap casting thread
Post by: mkawa on Tue, 25 June 2013, 00:24:15: how was shrinkage? they give pretty impressive shrinkage numbers (unbelievable almost for a tpu.. ) in the datasheet, but naturally ymmv with all hand-mixed cast and cured products..

hmm, it's a straight urethane. i guess that explains that.

i also wonder how memory is. i guess if you're hitting 90D in hardness, memory may not be so much of an issue, even in automotive applications...

this might be an interesting bushing material as well.
Title: Re: new DIY keycap casting thread
Post by: ishtob on Tue, 25 June 2013, 00:50:04: shrinkage of mold or keys?

I have yet to see any shrinkage in either, I have some urethane keys I made this time last year, and they have not changed much, still fits on the switches like the day it came out of the mold
Title: Re: new DIY keycap casting thread
Post by: DamnDan on Tue, 25 June 2013, 05:45:33: Is there any option to produce ALPS keycaps this way? Or will the material not be strong enough to handle ALPS thin stem?

If you ever produce anything ALPS i am buing it :P

Great work, thanks for sharing :)
Title: Re: new DIY keycap casting thread
Post by: theman2492 on Tue, 25 June 2013, 09:56:56: Quote from: ishtob on Mon, 24 June 2013, 23:51:37
its dirt cheap in terms of material... i still got 50% of the resin left, but the cure time and also cleaning up the flashing, inspecting and sanding that takes up a lot of time. It took me almost a week to complete this set of DSA

*material-wise if you don't include the cost of the silicone for the mold, I've spent about $50, so that means the above set costs about $25 plus a couple hundred hours of work

the amount of time depends on how many molds you are willing to make, but sanding and cure times are still the same.
if you are good, you might be able to make 3 keys before your task 2's pot life is over.
Title: Re: new DIY keycap casting thread
Post by: ishtob on Tue, 25 June 2013, 11:08:32: I did attempt 3 keys, but was unhappy with the result, as I cut really close to the end of the pot life, and the resin have issue setting in the stem part of the mold of the last keycap
Title: Re: new DIY keycap casting thread
Post by: ishtob on Tue, 25 June 2013, 11:09:41: Quote from: DamnDan on Tue, 25 June 2013, 05:45:33
Is there any option to produce ALPS keycaps this way? Or will the material not be strong enough to handle ALPS thin stem?

If you ever produce anything ALPS i am buing it :P

Great work, thanks for sharing :)

You should be able to do this with alps and topre
Title: Re: new DIY keycap casting thread
Post by: mkawa on Tue, 25 June 2013, 11:52:58: shrinkage is measured as ratio of size before and after cure (for resins that cure..)
Title: Re: new DIY keycap casting thread
Post by: nubbinator on Tue, 25 June 2013, 23:29:35: So did you mix those two resins together to cast those caps?
Title: Re: new DIY keycap casting thread
Post by: ishtob on Wed, 26 June 2013, 02:34:47: no the resin I use is the TASK2
Title: Re: new DIY keycap casting thread
Post by: Sifo on Wed, 26 June 2013, 02:47:18: Wow those look really nice. You need to hook me up in the future with some colors too, I can't wait to get the prototype ;D
Title: Re: new DIY keycap casting thread
Post by: mkawa on Wed, 26 June 2013, 10:33:34: Quote from: ishtob on Wed, 26 June 2013, 02:34:47
no the resin I use is the TASK2
you mentioned crystal clear resin in the OP. did you use it with these castings at all? as a clearcoat maybe?
Title: Re: new DIY keycap casting thread
Post by: ishtob on Wed, 26 June 2013, 11:03:46: I used crystal clear resin last year to cast translucent keys, I didn't try mixing them as they are different materials, crystal clear is a epoxy resin while the TASK2 is a urethane
Title: Re: new DIY keycap casting thread
Post by: mkawa on Wed, 26 June 2013, 11:15:12: to be proper, i think task2 is actually a polyurethane, but feel free to correct me on that. that said, you should be able to mix most epoxies and polyurethanes. i suspect what would come out would have the hardness of an epoxy without the brittleness. either that, or it will have low temp resistance and be brittle and hard to work with. it probably depends on mix ratio..
Title: Re: new DIY keycap casting thread
Post by: ishtob on Wed, 26 June 2013, 14:29:57: yes you are correct, I will try out mixing them soon. Polyurethane has much better heat resistance, and if you work with it within the first 2 hours after casting, its soft enough to work with ease. After that it get stupidly hard.

I am currently in the middle of moving out of my apartment, so I have not had the chance to purchase any epoxy. I will get it once im settled in my new place
Title: Re: new DIY keycap casting thread
Post by: ApocalypseMaow on Wed, 26 June 2013, 14:36:56: That's it! I'm making my own keys!!!
Title: Re: new DIY keycap casting thread
Post by: mkawa on Wed, 26 June 2013, 14:38:21: Quote from: ApocalypseMaow on Wed, 26 June 2013, 14:36:56
That's it! I'm making my own keys!!!

YES

+10pts for ishtob :D
Title: Re: new DIY keycap casting thread
Post by: mkawa on Wed, 26 June 2013, 14:42:40: Quote from: ishtob on Wed, 26 June 2013, 14:29:57
yes you are correct, I will try out mixing them soon. Polyurethane has much better heat resistance, and if you work with it within the first 2 hours after casting, its soft enough to work with ease. After that it get stupidly hard.

I am currently in the middle of moving out of my apartment, so I have not had the chance to purchase any epoxy. I will get it once im settled in my new place
some googling has led me to believe that they may mix best under pressure. i'm not a polymer chemistry wizard (i spent undergrad chemistry breaking lab gear for fun), but if so, a mixing cylinder would certainly be a cool toy. one of my sibs' friends at usc is playing around with a resin i don't understand but is extremely stable and he has a cool cylinder he build that can literally push the resin up to a constant temperature and sit and watch its time variant behavior; in his case some expansion and bubbles form (although cavitation or boil i don't know).
Title: Re: new DIY keycap casting thread
Post by: SeriouSSpotS on Wed, 26 June 2013, 14:49:27: Show Image
Quote from: ishtob on Mon, 24 June 2013, 23:30:36

(http://i6.photobucket.com/albums/y222/icbob/DIY/MYOC/null_zps06569829.jpg) (http://s6.photobucket.com/user/icbob/media/DIY/MYOC/null_zps06569829.jpg.html)

They look awesome!
Title: Re: new DIY keycap casting thread
Post by: nubbinator on Wed, 26 June 2013, 16:10:54: Quote from: ApocalypseMaow on Wed, 26 June 2013, 14:36:56
That's it! I'm making my own keys!!!

It's a lot of fun. I've been experimenting with both metal casting and resin casting and plan on checking out the Task2 mentioned here (it was next on my list to try anyways). I'm also looking at trying to either make my own or find a cheap pressure pot to use so I can crush the bubbles out of my casts.
Title: Re: new DIY keycap casting thread
Post by: ishtob on Wed, 26 June 2013, 18:17:28: if you are doing 2 keys at a time with the TASK2, you will have enough pot life to tap out most of the bubbles after mixing part A and B, I only get bubble that's big enough to be noticed 1 out of 5 keys I make
Title: Re: new DIY keycap casting thread
Post by: mkawa on Wed, 26 June 2013, 20:33:47: harbor freight has tons of cheap pressure chambers though, fwiw (although not clear... hmm..) as well as press frames that can be used to apply reasonably large and small amounts of pressure to them. high tolerances and failure rates, obviously, but cheap enough to play around with. actually come to think of it, i'm like 90% sure one won't need a mechanical frame to get enough pressure into this material. the mite itself might do the job, and it will general reasonable amounts of pressure in pretty much any container.
Title: Re: new DIY keycap casting thread
Post by: jwaz on Thu, 27 June 2013, 19:43:47: (http://i.imgur.com/c9h17Uf.jpg)
Title: Re: new DIY keycap casting thread
Post by: Sifo on Thu, 27 June 2013, 20:22:51: whoah wtf jwaz hook me up I need one for my keychain
Title: Re: new DIY keycap casting thread
Post by: ishtob on Sat, 29 June 2013, 00:37:11: Quote from: JesuswasaZombie on Thu, 27 June 2013, 19:43:47
Show Image
(http://i.imgur.com/c9h17Uf.jpg)

from what I understand, the 60psi recommendation actually damages molds, I've read that 40-50 is more ideal and is able to rid the casting of bubbles
Title: Re: new DIY keycap casting thread
Post by: kurplop on Sat, 29 June 2013, 07:07:25: I plan on casting some keycaps soon and would like some clarification. I have heard that the mix should ideally be vacuumed after mixing to remove bubbles but then pressurized during casting for the same reason. Is that correct?How important is that for good results?

Also, I see you use TASK2. Does that give you enough working time? Would TASK3 be too slow at 20min. pot life 90 min. demold time vs. 7 and 60 for TASK2?

Thanks for restarting this thread.
Title: Re: new DIY keycap casting thread
Post by: mkawa on Sat, 29 June 2013, 07:53:31: that makes sense to me. ideally when you insert the material into the mold you want to do it under at least low pressure to fill the voids in the mold (1). but the potting resin you use should be as free of voids and other defects as possible. one want to do this is to put it under vacuum with a filter such that oxygen can escape but the polymer itself cannot (2).
Title: Re: new DIY keycap casting thread
Post by: alaricljs on Sat, 29 June 2013, 09:35:03: If the polymer is prone to off-gassing, then vacuum can mess up your cure.
Title: Re: new DIY keycap casting thread
Post by: mkawa on Mon, 08 July 2013, 10:33:52: don't we take care of that with the filter media?
Title: Re: new DIY keycap casting thread
Post by: alaricljs on Mon, 08 July 2013, 11:07:48: Eh? Vacuum forcing the off-gas to happen at an accelerated rate can change how the polymer cures. Not my problem to solve the sniffing fumes issue :)
Title: Re: new DIY keycap casting thread
Post by: mkawa on Mon, 08 July 2013, 18:06:46: crap