I am thinking some 4" stainless half pipes with tapered ends welded in. When cooled two halves would make a nice round chunk to go in a crucible.
I'm not sure how SS does as a mold. I use some 1/4" thick L beams that have the ends welded to a flat piece of 1/4" steel. Then I put salt all over the metal and put it in a bag of water so it would rust up really nicely. The rust prevents bronze from sticking to the steel and helps act like a releasing agent. I do like the two halves idea, seems to make sense to make the most of the space inside your crucible.
It depends on the metal. For aluminum cupcake pans work great. If they have Teflon coating on them you should grind it off or don't use them. The smoke will make birds fall from the sky. Soup cans are great too. You have to cut those off though which is easy enough. Both forms make for good turning stock. I pour bronze into open petrobond sand molds. I poured it into one of my cupcake pans once and had to destroy the cups to get it out. I poured it into a greensand mold once too and the sand stuck to it horribly. I think the burning oil in the petrobond creates a protective barrier and keeps the sand from sticking. It seems awful hard on the sand though. Pete
I used to use a mini-loaf baking pan turned upside down as a sort of match plate for making greensand ingot molds. But recently I poured a copper ingot into one of the loaf-holes in the pan itself. I'd done it many times with aluminum. Knew it was asking for trouble pouring copper in it, but did it anyhow for lack of having anywhere else to dump the leftovers. ...I still need to go back and cut the thing out again. So much for my ingot mold match plate... If I can find another pan like it, I'll buy it for sure and start doing the same thing again, it worked great. I suppose you could just sand draft on some blocks of wood and screw them to a piece of plywood or something instead. Pete, I found adding just 1% sea coal (actually bituminous coal dust I got from a local blacksmith) to my greensand cured it 100% from wanting to stick to my bronze castings. I was seeing that happen on all my bronze castings at first when I switched to my homemade sand, not just the ingots. I think the cast iron guys use it too for similar reasons, but at a slightly higher percentage from what I've seen. Jeff
No idea, I made a point of hunting down bituminous because that's what Ammen's handbook said sea coal is, and that sea coal improves "peel" (aka sand not sticking). Turns out, Nova Scotia (by the sea!) bituminous is all Josh uses, and I don't know any other smiths I can hit up for a bag of sweepings. Might be worth mixing up a small batch just to see, if no one else has the answer... Jeff
For aluminum or ?... I'd suggest you consider smaller ingots rather than two halves that fill a crucible for several reasons. The inside diameter of a crucible typically narrows from top to bottom and any thing that fits the ID closely will expand at the contact point when heated and potentially brake the crucible. Smaller ingots mean you can add them in increments so it doesn't drop the temperature of your melt (if you don't preheat them). It also makes it easier to control the weight of the initial charge. Smaller pieces have more surface area, melt faster, and formation of a good heal can further accelerate the melt compared to a larger mass. I use triangular ingot made from angle iron for the reasons above and because they nest/pack well vertically in the crucible. Angle iron is hot rolled and has a very thick oxide layer which resists sticking and metal contamination. It's a total non-issue for aluminum and pretty good for copper alloys but some graphite still isn't a bad thing for copper alloys....they can braze themselves to bare spots. Did you switch gears and really mean crucible? or ingot tray? If latter, a crude sand mold for iron ingot. Best, Kelly
Kelly, What you said makes perfect sense and your pictures make it clear. That’s what I need to do. Yeah I did shift gears with the crucible question, sorry about that.
Iron = ceramic bonded clay graphite as in Morgan Super Salamander, which will work for everything else you likely do as well. Some prefer tar bonded silicon carbide for non-ferrous work. Morgan's brand for those is Starbide but there are other manufacturers of both. Best, Kelly
Yup.. Metoo. 1/4" Angle iron with some draft on the ends. Nothing sticking to that and no coating needed. Morgan graphite all the way. Still not sure the reason for pricey silcon carbide. Too rich for my blood.
I kind of like the large muffin tin I've been using. After watching THIS, I want to wrap a SiC crucible in kaowool, pop it into microwave and see what happens.
That's old hat. The craft biddies have been melting glass in the mic for years. No one bother to ask how they anneal that stuff
Allow me to rephrase, I want to nuke a crucible loaded with aluminium or bronze and see what happens.
Do it long enough and it will melt. I think I've seen some clown on YT do it. Bigger question is why?
