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geekhack Community => Keyboards => Topic started by: Setiawan on Mon, 27 April 2020, 09:28:33

Title: 3D printed Topre domes?
Post by: Setiawan on Mon, 27 April 2020, 09:28:33
It's come to my attention that 3D printers can print TPU. While it's not exactly rubber, it is kind of flexible and I'm guessing can be made into a collapsible dome. Have there been any known instances of people attempting to print TPU domes? Or is this simply not viable for some reason?
Title: Re: 3D printed Topre domes?
Post by: Riverman on Mon, 27 April 2020, 11:13:23
TPU seems like it would be way too stiff for the rubber dome on a keyboard.  That's the stuff they make transparent cell phone cases out of (the ones that yellow all the time), and it tends to be very stiff.
Title: Re: 3D printed Topre domes?
Post by: Polymer on Mon, 27 April 2020, 11:50:57
You can certainly make rubber domes...you can make TPU domes that would collapse.

Could you find the right combination where it feels right?  I don't know..and would this make sense from a cost perspective?  Probably not.

If this was just your own personal pet project, I suppose that would work out...but commercially it probably isn't worth it...

Thankfully there are other ways to get Topre/Toprelike domes....
Title: Re: 3D printed Topre domes?
Post by: Setiawan on Mon, 27 April 2020, 20:17:45
Well, I have a 3D printer coming in a few weeks. After I learn the ropes, I'll try to print some out and report back how it goes :)
Title: Re: 3D printed Topre domes?
Post by: Leslieann on Mon, 27 April 2020, 20:49:57
While you could to print one that functions I would put little faith in being able to print multitudes of them consistent. Out of 100, 90 would probably work, which is fine, the problem is of those 90 you would end up with 20 different spring rates.

There is also a matter of the time involved, the more precision you want the slower it will print.  The longer a print takes and the more parts it has the more likely it will fail, a 100 piece 3 day print is not my idea of fun or smart.

My advice, print one, then use silicone and resin to make a mold, preferably a mold that can do 20+ at a time. You have more options for material density, you could use microbubbles to alter it further and each attempt will be more consistent and less risk of failure. Faster as well if you do it right. You could even do it this way without the 3d printer though it would limit you a bit.

I would even consider a resin printer for this as they handle smaller, finer precision stuff better. Just beware, resin printers are best not used in your house, they're extremely messy and give off harmful gasses.