Creating 3D QR codes

[jsc]

Try a lighter. You want very localized heating, and you shouldn't need that much heat I would think. You could also pre-cool the ends by spraying it with canned air turned upside down (very carefully).

The plaster is a good idea.

[Toby]

Tried the lighter but it didn't put out enough heat. The plaster dissipated it too fast.

Tried another technique of heating up the plaster on the stove without the filament inserted, then once it was hot, inserting both sides at once. It did have some effect on the filament state, but when it cooled and I broke the mold apart the two ends hadn't fused.

A more involved approach might work: Build the plaster jig as a two part piece by modeling and printing top and bottom molds for it in PLA. So it ends up as two blocks of plaster with matching channels for the filament. Make the top piece not as long as the bottom so it just covers the center portion where you want the fusing to take place. Then secure the two strands of filament in the bottom channel, heat the top piece on the stove till it's good and hot, and place it over the joining point. So then they fuse, theoretically.

[jsc]

I'm going to have to get some plaster, it sounds like a useful material to have in my box of tricks. Anything I should know about it? Are there different kinds?

[ednisley]

As is always the case, Thingiverse offers many filament splicer designs, ranging from the sublime to the ridiculous:

http://www.thingiverse.com/search?q=filament+splice&sa=

No experience with any of 'em, though.

[Toby]

I'm going to have to get some plaster, it sounds like a useful material to have in my box of tricks. Anything I should know about it? Are there different kinds?

Two kinds that I've used:

Straight plaster of paris that you can get in a hardware store like Home Depot or Lowes. Very cheap.

So called "Art Plaster", which is plaster of paris mixed with things to make it more break resistant. This is what I've used mostly. You can get it at stores like Hobby Lobby or Michaels, where it's vastly overpriced (though check online for coupons- they usually have 40% off any single item). Or you can get it online from Amazon where it's cheaper if you have Prime shipping.

If you make molds with PLA, it helps to release the plaster if you coat the inside of the mold with some stuff called "Johnson Paste Wax". Also available at hardware stores and cheap. If you tell them what you're doing they'll probably try to sell you some toxic aerosol. This is old-fashioned, non-toxic and works better than anything else I've tried.

Plaster is simple to work with but you'll have to learn about how it sets (rapidly, when you're not looking) by practicing with it.

As is always the case, Thingiverse offers many filament splicer designs, ranging from the sublime to the ridiculous:
http://www.thingiverse.com/search?q=filament+splice&sa=

That cracked me up. Makes me want to pursue this idea with plaster, if for no other reason that to add something to the circus.

[jsc]

Toby, what is the brand name of the plaster you use? Searching Amazon comes up a lot of hits, including something called, literally, "art plaster" by Activa, but it's not prime. I just want the same thing you have.

[Toby]

The stuff I usually use is called Permastone, also by Activa. It sells at Hobby Lobby for $10 for 28 oz, but with the 40% off coupon on their web site it comes down to $6. That is Prime on Amazon, but the price is also $10 +/-, so no savings there.

I also have some Activa art plaster from Amazon. I must have been mistaken about it being prime. That comes out to $17 for 5 pounds, so $3.40 a pound vs $3.40-something for the Permastone with the coupon. So the same.

I tried the art plaster once and found it had different setting properties than the permastone, which I was already familiar with. So I've gone back to permastone and just pick up a new box with discount every time I go near Hobby Lobby (they only allow one discount for one item per customer per day, though it's not like they check id or anything.)

So if you can find it locally with discount, permastone is what I'm most familiar with. Otherwise you have the choice of paying more for it from Amazon, or going with the Art Plaster and learning to use that. It can't be very much different, but I have to say, that permastone is seriously hard to break. In order to crack that mold last night I had to whack it, hard, about 5 or 6 times with a hammer.

[Toby]

BTW, check out the picture on the box of Permastone on Amazon and ask yourself, "Now where have I seen that lately?"

[Toby]

Also in terms of safety, this is gypsum plaster which is pretty mild stuff as far as these things go. (unlike lime-based plaster, which can burn you in various ways). But still it doesn't hurt to use precautions- I generally wear a dustmask when I'm mixing it and sand the finished pieces outside.

Also don't ever put it down your sink- either dry or mixed. It will settle in the trap and clog your pipe. I keep a bucket of water around for rinsing off my hands and tools, and every once in a while clean out the sediment on the bottom.

And as far as experimental things go like heating it up to melt filament, that's a case of use your own good judgment and exercise appropriate caution. I don't think this stuff has a tendency to explode when heated, but I wore goggles when I was heating it last night just in case.

[jsc]

BTW, check out the picture on the box of Permastone on Amazon and ask yourself, "Now where have I seen that lately?"

I don't get it.