Creating 3D QR codes

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jsc
Posts: 1863
Joined: Thu Apr 10, 2014 4:00 am

Re: Creating 3D QR codes

Post by jsc » Mon May 12, 2014 4:28 pm

DSM has some nice draft features, but I ended up just double filleting both corners with overlap.

I modeled the molds by modeling the positives first, then took the profiles to make the negatives.

Toby
Posts: 330
Joined: Wed Apr 09, 2014 9:44 pm

Re: Creating 3D QR codes

Post by Toby » Mon May 12, 2014 5:47 pm

If you ever want to finish something cast in plaster, you'll never guess what works well with it: Diluted Elmers! I didn't invent this, it's apparently well known is sculpture circles.
plaster_finish.jpg
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jsc
Posts: 1863
Joined: Thu Apr 10, 2014 4:00 am

Re: Creating 3D QR codes

Post by jsc » Tue May 13, 2014 3:19 am

Well, I got some paste wax today and got a clean mold. But it is pretty fragile and has a tendency to shed plaster powder. I tried to rinse it off, but that just dissolved it away pretty much. And I think heating it basically turns it back into the powder. I know they use this stuff to cast metals, so it might be possible, but I think some sort of ceramic clay would be better.

Still, a good thing to have around. I'm going to try some more ambitious molding projects.

While googling around regarding glue, I noticed people add glue right into the mix along with the water for strength. Have you tried that?

Toby
Posts: 330
Joined: Wed Apr 09, 2014 9:44 pm

Re: Creating 3D QR codes

Post by Toby » Tue May 13, 2014 4:01 am

I'm stoked that you got a good cast from this method! Keep me posted on what else you try.

Do you mean after the plaster set and you removed it from the mold, there was plaster dust that came off when you handled it? With permastone that doesn't happen. Once it sets it doesn't shed unless you abrade it on purpose.

You could try sealing it with elmers but I don't know what the heat will do to that.

I haven't tried mixing elmers in permastone because that's already so strong by itself. But I have been meaning to try it in straight plaster. Maybe with Art Plaster that will help as well.

I agree that clay/ceramic is the way to go for a DIY solution to splicing. I have all the stuff for a test- the soldering iron didn't work so I got a small blow torch, but I haven't tried it out yet. Maybe time for that...

jsc
Posts: 1863
Joined: Thu Apr 10, 2014 4:00 am

Re: Creating 3D QR codes

Post by jsc » Tue May 13, 2014 5:38 am

It may have been my mixing. I didn't do a very precise job with the ratios, just added water until it was pasty. I'm going to try it once more, then move on to another idea: use a heated penny as a "tongue" to lap the ends with, then quickly introduce them into a channel for welding and forming.

Plaster casting is pretty cool in itself, though! Making things to make things.

Toby
Posts: 330
Joined: Wed Apr 09, 2014 9:44 pm

Re: Creating 3D QR codes

Post by Toby » Tue May 13, 2014 6:11 am

You want to do it the other way: put the water in a small plastic container and then add plaster to it a spoonful at a time. Don't stir right away, just let the plaster soak up the water, then stir it slowly. The consistency you're looking for is like pancake batter or heavy cream. You'll be surprised how much plaster you have to add to get there. If you overshoot, you can add more water but once you start stirring that sets the chemistry in motion so you don't want to do too much of that.

After you pour it you also want to vibrate the mold a bit to get out air bubbles. I do this on a glass kitchen table and what I usually do is just rap on the underside of the table a few times.

For cleanup, let the excess plaster set in the container, then deform it a bit and the solid plaster will come right out. And remember not to wash anything down the sink, even rinsing your hands off under the faucet is too much IMO.

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