Thursday, June 18, 2015

Destroyed another crucible: the aftermath.

As I mentioned previously, I've bought a proper crucible. I'm still saving it though (yes, stupid) until I get my melting and furnace skills down. Instead, I continue to use stainless steel canisters from "my favorite store". Quick aside, if you are wanting to buy but can't find any SS canisters at any Goodwill stores in the Austin area, my bad.

Last week I was melting some junk aluminum (i.e. Lone Star cans) to replenish my stock. As happens when melting trash aluminum like that, it got to the point to where the crucible had a huge head of dross. This time though there wasn't as much pourable aluminum as I expected. 

I pulled the crucible and, sure enough, I blew a hole in another one! I noticed a small glowing bit of aluminum in the bottom of my furnace. No biggie, I thought, I'll shut everything down, let it cool, and scoop it out next time.

Well, mistake number eleventy billion, it wasn't just a bit! When I went to fire up the furnace for tonight's mayhem, I couldn't even see the burner inlet! I'd melted enough aluminum that, once it solidified, it was at the top of the pipe. 

That explains why I was going through so many cans but not getting any aluminum. They were "disappearing" faster than I could drink them. Actually, that last sentence explains why it got so bad before I noticed. (Yeah, well, don't judge. You are reading this blog and presumably saw the URL/title after all. Therefore you should expect this kind of nonsense.)

So, before getting down to any melting tonight, I had the chore of removing my custom aluminum furnace liner. My first thought was to fire it up, let it melt, and then scoop but there was way too much aluminum for that. Plus, when it solidified, it ran back up the pipe so that was mostly plugged.

Chiseling wouldn't work because it was way to thick and, even if it wasn't, I'd most likely destroy the refractory lining. Instead, I started off with an angle grinder to try and cut it in to pieces but that was quite unwieldy. 

Then I switched to the power drill. I killed a few cheap drill bits trying to drill around the burner pipe but I eventually (2 hours later!) got the chunk of aluminum out.

The remaining bit of aluminum in the pipe was small enough that I could heat it up, courtesy of the burner itself, and use a hammer and punch to drive it out.

Finally, now it's time to get some real melting done. (With special attention paid to the crucible, of course.)

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