Apr. 23rd, 2017

randomdreams: riding up mini slickrock (Default)
We went to the Ingress cross-faction awards ceremony for the Colorado area on Saturday. They hold it in a kind of divey artist gallery on Santa Fe, but there are usually at least a couple of good sculptures.
Both these were basically 2 meters tall.
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Two of my coworkers have bought the same model of 3d printer that I have. One printed a tiny crossbow, that is almost entirely a single print: all the moving parts (and there are several) were printed in one go, assembled, relying on flex to enable it to work.
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I think it's funny that so far he has printed a fidgeter (a weighted spinny thing) and the plastic equivalent of brass knuckles and a crossbow and a skull. I have printed a testbed for one of my circuit boards, an enclosure for another circuit board, an intake manifold, and motor hold-down brackets. The other guy has printed a klein bottle and another mathematical oddity, related to a moebius strip. We all seem to be quite consistent in our choices, although they are all quite different.

I bought a pipe nipple and cap, intending to weld them together to make a small heavy-duty crucible for melting and casting brass, insofar as my aluminum one is intended for much larger volumes and much lower temperatures. The nipple and cap both claimed to be galvanized steel. I sat them in hydrochloric acid for about 20 minutes and then went to weld them. The HCl did not sufficiently strip off the zinc in 20 minutes: I should have left it in there for an hour.
This is what it looks like when you try to weld something galvanized.
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Zinc fumes are bad for you. Avoid doing this.
As it turns out, even though they both claimed to be galvanized steel, the cap was in fact cast iron. I should have tested it before trying to weld it.
This is what happens when you use standard welding rod to try to attach steel to cast iron.
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See that big old crack horizontally right down the center of the weld? The cast iron has melted and run up to that point, but because it is brittle, when it cools it contracts and cracks. (Steel is ductile enough to stretch just a little as it cools.)
This is definitely not going to hold liquid brass without leaking everywhere.
I'll fabricate another one later.

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