Buying Crucibles and other what nots.

The Shop > Metal Stuff

<< < (4/6) > >>

awemawson:
I did have a magnesium fire at my last place when I had my furnace set up. All was going well, I poured some 1" diameter piston moulds for a friend who was building a V12, came to scrape out the glowing crucible and off it went. Obviously a high magnesium alloy rather than pure. I just covered the crucible in dry sand and left it to sing to itself for an hour or so then came back and finished cleaning up.

I expect that the extra supply of oxygen was what did it - I never had any of the moulds burn up, but they would have a very limited oxygen supply in the cavity.

Source metal was alloy pistons from a large commercial diesel engine.

NeoTech:
My furnace i made this weekend out of an old 25l Hydrophone is, 180mm wide and 220mm deep. And lined with about 10cm of brick and 1100C fire "proof" mortar.. Im gonna tinker together burner.. (basicly copy what you did there)..

But thanks i make a crucible from one of the pipe.. i have no problem lifting heavy objects up and around 70-80kgs, so imagine a crucible with about 2-3kg of material shouldnt be much of a problem.. But will do that sand test, sounds sensible. =)

thanks alot! =)

vtsteam:

--- Quote from: awemawson on July 15, 2013, 03:26:35 PM ---I did have a magnesium fire at my last place when I had my furnace set up. All was going well, I poured some 1" diameter piston moulds for a friend who was building a V12, came to scrape out the glowing crucible and off it went. Obviously a high magnesium alloy rather than pure. I just covered the crucible in dry sand and left it to sing to itself for an hour or so then came back and finished cleaning up.

I expect that the extra supply of oxygen was what did it - I never had any of the moulds burn up, but they would have a very limited oxygen supply in the cavity.

Source metal was alloy pistons from a large commercial diesel engine.

--- End quote ---

Yikes! Well you did the right thing and had the space where it wasn't a big problem so all in a days work, I guess. Must have been a surprise!

Diesel pistons of magnesium alloy. That's a new one on me. Melted plenty of pistons -- But I believe it. Somebody gave me an old VW Beetle block (cracked) which turned out to be magnesium. Still have it.

Haven't had a magnesium fire yet, except for test shavings. Don't want one either.

How did the little V-12 turn out?

NeoTech:

So i imagine my small furnace will prob having no problem with aluminium. This during the suggested "burn-in" with just charcoal and a shop vac. Thats the max of the ir temperature thingy as well ..

vtsteam:
You're on your way Neotech! Aluminum melts very well in a small charcoal (store bought briquette) furnace. When I got my method down while building the Gingery lathe I used to figure on a 20 minute melt for 2-3 pounds of aluminum. It had an 8" bore. And because of all the carbon monoxide (please run it outdoors, always) the aluminum had minimal dross.

First ones take a little longer to melt, but it pretty quickly becomes routine. A large stainless steel kitchen spoon is ideal for removing dross before the pour, and a 1/4" steel rod poker comes in handy for a million different things. Don't stir the aluminum or you will create more dross and hydrogen porosity. Leave the dross (and bits of charcoal) on the melt until just before pouring. They protect thee melt. But do push pieces of unmelted aluminum down into the melt with the poker. A quick dip with it will also tell you if things are completely melted, and if it comes out thin and clean its time to pour. If thick and crusty, too cold.

Well with your thermometer you probably will have a very accurate means of judging anyway. I just had a poker. Good luck.

Navigation

 Message Index

Go to full version