How to Temper a Graphite Clay Crucible for Metal Casting at home

I got a new crucible let the casting wait until after I temper this if you remember back to the keychain video I successfully made some keychains what I didn't show in there because I didn't realize until later that crucible died I was using the bottom of a fire extinguisher cutoff and when I was cleaning up afterwards I noticed these things in the bottom little lumps of aluminum it was leaking and I looked at it and found a couple of small holes and and there's sort of a reason for that think of aluminum kind of like water and the steel crucible is sort of like if you were to take like sugar and make a cup out of it the water will dissolve the sugar and that's what aluminium does it kind of dissolves other metals into it and that's how you make alloys you dissolved metals into other metals but that's why I got this to replace it graphite clay this will not dissolve into the aluminum it's bigger than my other crucible the one for melting copper that's because I don't need to put as much fuel around this aluminum melts pretty easily but you can't just buy it and use it step one in tempering this is to put it in your oven so I put in my oven for about probably an hour maybe I was only paying attention at 300 degrees and the diet does is it drives out all the moisture you don't any moisture anywhere near anything to do is the foundry because water will flash boil and it will flash foil inside so this was sitting in a bunch of rain water and I you know let it air dry for 20 minutes and went through in the furnace there's still a lot of moisture inside and it will flash boil and break the thing so I drove out all the moistures only know where it was before I got it could have been in a damp warehouse and the next step is to temper it so I got the furnace here and we're going to burn it in the furnace I'll burn it but you get the idea so I don't know exactly the temperature we're going to put this in but it has to get red hot so hot enough but the whole thing is glowing red which is pretty hot how does it need to melt aluminum not as hot as you need to melt copper I think copper has to glow like orange yellow so here's the color is a color shift no color not hot enough to glow then I kind of dull red orange II yellow then it kind of whitish yellow and I'm white which is super bright super hot you need welding glasses we're just going to go for red for a while like an hour or not an hour but no heat up to red hot and then let it cool off basically I am happy to report that this hairdryer is now officially my furnace hairdryer for exclusive foundry use I guess my wife couldn't stand that her hair dryer smelled like charcoal briquets and copper so you know I guess score one for me also she bought a new hair dryer and then informed me that I paid for it and I can have our old crappy one it really is better to ask for forgiveness rather than permission although you know if they say happy wife happy you get to do what you want so keep your wife happy people well it's heating up I should probably mention you can actually use steel as a crucible I think they're great as disposable ones like if you XML bloom it'll cans like I did that left a lot of crap and then inside of the crucible and I thought was a clay crucible out and what a really sad but I got that Englisher for free so I guess if you can use them as expendable objects and just throw them in the garbage when you're done go for it I also know people who use steel crucibles that are sick probably like 3/16 inch thick pretty sick stuff that fire extinguisher is probably more like 18-gauge steel pretty thin stuff so it dissolves really quickly I don't know that as field gets resolved into the metal it'll mess with the alloy a bit personally I'm not doing anything that has to be perfect a hollow I am not making engine parts I'm making like keychains and crap although pretty soon I'll be doing a lot more larger more complicated stuff but none of its ultra critical that the the alloy be perfect which is great because I can't do perfect I'll try but not going to happen okay charcoal burned out time to put in the crucible she's going to make some room on the festive directly on the bottom like so is very little charcoal left actually it's pretty much all gone and what I did here was basically just preheat the furnace may not of refractory cement so the walls of the furnace hold an awful lot of heat now I'm going to add a bunch more charcoal all around it and then we're going to crank the sucker up remember this is just an empty crucible not casting anything we're tempering a crucible so it fell in the middle doesn't matter not casting anything right now okay goo and now let it burn evil laugh as I mentioned there are a couple different kinds of crucibles I'm using right now a graphite clay crucible which is kind of a standard one for a lot of people doing casting at home and they're there for like anything that melts that copper temperature and lower basically so copper gold silver brass aluminum that kind of thing if you want about iron you need a different kind of crucible so that needs to get a lot hotter but yeah just just remember pick a crucible designed for the metals that you're trying to melt okay by now the crucible is very very hot I will show you I've also had to refill the charcoal a couple of times but just on the one side with a hairdryer goes in over there see we're talking very very hot one comment about furnace design the hairdryer goes on this side and I kind of blows in at an angle so the air goes around the crucible well it's full of charcoal so there's not a lot of air flow so it tends to burn up on the charcoal on this side not so much here right before the vortex gets back to the hairdryer I don't really like this because it heats it up heats up that side of the crucible a lot more all right so now it is still sort of red and most of the fuel a lot of it anyway is burned away so here is how I'm going to let it cool naturally put that up there to save the heat turn that off remove and that's it you let it cool inside there that keeps in the heat and let it cool very very slowly and that's what you want you want slow cooling don't take it out and just set it on the ground don't spray water on it it'll explode leave it in there and leave it in there for like a day the rest of the day because it's super hot but it cools slowly and then it will be tempered and ready to go and here it is done this is many hours later I let it sit I probably let it sit for six to eight hours I fired it like just after lunch and it's well has dinner now it looks slightly different this doesn't look as different the inside doesn't look that much different but this does look different because this was getting the hairdryer blowing next to it so this was getting fresh face melting temperature from the burning charcoal but now we are ready for casting which is good because I got a couple of casting projects I want to start especially with my increased amount of sand now one thing that I'm going to do with this I'm probably not going to use it until I get like a actual crucible pongs they don't want to wreck this one up quite so badly and also I'm never going to melt cans in this one probably not going to melt cans again that was the unpleasant smelling experience if you're wondering how the furnace is doing and used it multiple times and take a look still looks like new huh not bad this is a much better material actual refractory cement there is actually room even though this is a largest crucible I've ever had of like the three there's still enough room around it for a bit of charcoal so those lump briquettes work pretty well I think in here because you can fit a bunch of them down in between and it gets more than hot enough to melt aluminum easily hot enough for aluminum and then done you have a crucible that you can use without fear of it breaking apart it could still break apart don't ever don't ever forget that it's made out of clay I could drop that on the floor once and smash it's gone on that note don't let your crucible get damp always keep it somewhere dry and if it's been kind of damp for a while throw it in the oven for an hour so at 300 degrees drive all the moisture out before you use it because it will blow up and that's that's bad blowing up is bad when somebody's pulled molten metal because molten metal hurts it's a little bit little bit burning so be careful with that [Music] Oh [Music] [Music]

Channel: Paul's Garage

Views: 66,647

Rating: 4.8458118 out of 5

Keywords: metal casting, how to, Metal casting crucible, Tempering, beginner metal casting, metal casting process, metal casting at home, casting crucible, crucible, mini metal foundry, metal foundry, trash can, how to make a crucible, graphite crucible, diy crucible, ceramic crucible, how to temper a crucible, preparing a crucible for casting, paul's garage, homemade crucible, casting metal, clay crucible

Id: wWAJPlrcQVY

Length: 9min 11sec (551 seconds)

Published: Fri Mar 10 2017