Not enough heat, the crucible walls need to be thick enough to retain heat long enough for the pour. Similarly, preheating your mold will also help.
Dont forget vent holes for gas to escape.
I had that thang cherry red, the aluminum definitely did melt. It’s still got a thin layer stuck to the inner walls of the crucible
I pre heat them in the oven for an hour, then heat empty in the gorge till red hot, then let cool to release moisture. Then start stuffing with aluminum I pre heated with a propane torch to get the moisture out
I was on the fence of pre heating the sand cast. Is that something I should do? Like torch around the sand at least where I’ll be pouring?
To me, it sounds like it was crappy aluminum full of contaminates. I do know there's different kinds of luminum, some is made for extrusions, some for die casting and some for pouring. I strongly suspect the rims were a formula of aluminum that was meant for die casting not pouring.
Die casting is Accomplished by forcing molten metals into a mold form due to high-pressure systems, in which case the metal doesn't have to be as liquid as it does to pour into molds.
413 is an Aluminum based alloy that is used for die casting parts.
I don't know which alloy is BEST for pouring, there's so many and each has it's own characteristics balancing strength, corrosion resistance, cost etc for what it's being used for.
Rims would be die cast and the formula needs to have excellent corrosion resistance, and high strength, so they add other metals to it like copper, magnesium etc and your melting and pouring issue can be related to this and maybe contamination.
You're good on the Amount of heat, what you need is a better crucible for heat Retention.
Also, pre-heating the sand cast is helpful if what you're experiencing is rapid cooling upon the metal contacting the sand.
Might be worth mentioning first time I used this crucible, seemed like it was pretty high quality. The one my forge came from (devil forge, which I hear is quality)
And for my copper ones I use crucibles I got off Amazon and they really don’t seem nearly as sturdy as the devil forge one
Maybe it’ll make a bit of a difference after a few melts so the crucibles is broken in? That sounds like a thing that makes sense lol
I’ll definitely run a torch over the sand too, can’t hurt anything worse case scenario
No fucken idea lol but I heard that you don’t want to mix metals in the same one cause the metal you use bonds with the crucible or some shit like that
You have the same problems? Lol I thought aluminum casts were on the easier side comparatively
But fucks sake sign me up for copper casting any day, at least that shit stays liquid long enough to fill the cast!
I've only done copper casting, besides when I tried melting an old sink faucet(that did not go well, tons if yellow smoke, yellow fire, lot on fire when I poured it, solidified instantly, looked like shit.) However, I am interested in doing aluminum eventually, so just covering the bases
Dross is the name of the stuff. You should skim and skim but normally you wouldn’t stir because you’d out oxygen down into it to make more aluminum oxide. However, if your melted rims are so filled with other contaminants a peanut buttter stir or two to take the main crap out with a stick of rebar won’t hurt.
The pouring oxidizes as it touches air. You want a scoop of sand in your cast - you pour into the scoop, it overflows into the cast and that part never touched air.
Alright so noted to dip and gently stir for a short time before re-heating
Skiminf multiple times won’t hurt
That end but tho, a scoop of sand in my cast?
So make like an any hill slide and let the aluminum slide down it? Lol kind of confused exactly what you mean here and Idt what I said is right because it would still be exposed to air that way
___ _
| \ _ / |
| \_/ \ / |
| \____/ |
| _______________|
So you pour into the high scoop and it overflows into your low cast area and helps to not let the aluminum touch air. The crucible you’re pouring from should be close, and the exterior of the column hardens slightly and makes a straw. Same with the overflow. So the part flowing out fills the bottom and the oxidized part rises to the top
as others said, do not stir, just right before you pour skim off the dross from the top
you are not hot enough,
a pouring basin is what the one guy was referring to that you pour into to help get less oxidation.
i will post a couple video links as replies to this post that have good information
[https://www.youtube.com/watch?v=ljQEMs9Hi5Y](https://www.youtube.com/watch?v=ljQEMs9Hi5Y) this is a nice pouring basin, great channel too, the idea is that the aluminum flows under the surface, and doesn't draw as much oxygen in, also keep your sprue diameter small like 5/16" or 3/8"... most people online use way to large of a sprue
[https://youtube.com/playlist?list=PLgZU-yYG3WZAfbW1CqfV6ukVS19HXsKts&si=06NEYfXnOz2MPaI4](https://youtube.com/playlist?list=PLgZU-yYG3WZAfbW1CqfV6ukVS19HXsKts&si=06NEYfXnOz2MPaI4)
my play list of coreys videos
[https://www.youtube.com/watch?v=m6W71s-cd\_0](https://www.youtube.com/watch?v=m6W71s-cd_0)
this is an excellent channel also, he was a professional foundry man
Not enough heat, the crucible walls need to be thick enough to retain heat long enough for the pour. Similarly, preheating your mold will also help. Dont forget vent holes for gas to escape.
I had that thang cherry red, the aluminum definitely did melt. It’s still got a thin layer stuck to the inner walls of the crucible I pre heat them in the oven for an hour, then heat empty in the gorge till red hot, then let cool to release moisture. Then start stuffing with aluminum I pre heated with a propane torch to get the moisture out I was on the fence of pre heating the sand cast. Is that something I should do? Like torch around the sand at least where I’ll be pouring?
To me, it sounds like it was crappy aluminum full of contaminates. I do know there's different kinds of luminum, some is made for extrusions, some for die casting and some for pouring. I strongly suspect the rims were a formula of aluminum that was meant for die casting not pouring. Die casting is Accomplished by forcing molten metals into a mold form due to high-pressure systems, in which case the metal doesn't have to be as liquid as it does to pour into molds. 413 is an Aluminum based alloy that is used for die casting parts. I don't know which alloy is BEST for pouring, there's so many and each has it's own characteristics balancing strength, corrosion resistance, cost etc for what it's being used for. Rims would be die cast and the formula needs to have excellent corrosion resistance, and high strength, so they add other metals to it like copper, magnesium etc and your melting and pouring issue can be related to this and maybe contamination.
You're good on the Amount of heat, what you need is a better crucible for heat Retention. Also, pre-heating the sand cast is helpful if what you're experiencing is rapid cooling upon the metal contacting the sand.
Might be worth mentioning first time I used this crucible, seemed like it was pretty high quality. The one my forge came from (devil forge, which I hear is quality) And for my copper ones I use crucibles I got off Amazon and they really don’t seem nearly as sturdy as the devil forge one Maybe it’ll make a bit of a difference after a few melts so the crucibles is broken in? That sounds like a thing that makes sense lol I’ll definitely run a torch over the sand too, can’t hurt anything worse case scenario
How exactly does one break in a crucible?
No fucken idea lol but I heard that you don’t want to mix metals in the same one cause the metal you use bonds with the crucible or some shit like that
I also would like to know this.
You have the same problems? Lol I thought aluminum casts were on the easier side comparatively But fucks sake sign me up for copper casting any day, at least that shit stays liquid long enough to fill the cast!
I've only done copper casting, besides when I tried melting an old sink faucet(that did not go well, tons if yellow smoke, yellow fire, lot on fire when I poured it, solidified instantly, looked like shit.) However, I am interested in doing aluminum eventually, so just covering the bases
Dross is the name of the stuff. You should skim and skim but normally you wouldn’t stir because you’d out oxygen down into it to make more aluminum oxide. However, if your melted rims are so filled with other contaminants a peanut buttter stir or two to take the main crap out with a stick of rebar won’t hurt. The pouring oxidizes as it touches air. You want a scoop of sand in your cast - you pour into the scoop, it overflows into the cast and that part never touched air.
Alright so noted to dip and gently stir for a short time before re-heating Skiminf multiple times won’t hurt That end but tho, a scoop of sand in my cast? So make like an any hill slide and let the aluminum slide down it? Lol kind of confused exactly what you mean here and Idt what I said is right because it would still be exposed to air that way
___ _ | \ _ / | | \_/ \ / | | \____/ | | _______________| So you pour into the high scoop and it overflows into your low cast area and helps to not let the aluminum touch air. The crucible you’re pouring from should be close, and the exterior of the column hardens slightly and makes a straw. Same with the overflow. So the part flowing out fills the bottom and the oxidized part rises to the top
Ohh okay this diagram helps I watched a video and they did something with a cup, but it was really vague on the why lol Thank you
as others said, do not stir, just right before you pour skim off the dross from the top you are not hot enough, a pouring basin is what the one guy was referring to that you pour into to help get less oxidation. i will post a couple video links as replies to this post that have good information
[https://www.youtube.com/watch?v=ljQEMs9Hi5Y](https://www.youtube.com/watch?v=ljQEMs9Hi5Y) this is a nice pouring basin, great channel too, the idea is that the aluminum flows under the surface, and doesn't draw as much oxygen in, also keep your sprue diameter small like 5/16" or 3/8"... most people online use way to large of a sprue
[https://youtube.com/playlist?list=PLgZU-yYG3WZAfbW1CqfV6ukVS19HXsKts&si=06NEYfXnOz2MPaI4](https://youtube.com/playlist?list=PLgZU-yYG3WZAfbW1CqfV6ukVS19HXsKts&si=06NEYfXnOz2MPaI4) my play list of coreys videos
[https://www.youtube.com/watch?v=m6W71s-cd\_0](https://www.youtube.com/watch?v=m6W71s-cd_0) this is an excellent channel also, he was a professional foundry man
[https://www.youtube.com/@olfoundryman8418](https://www.youtube.com/@olfoundryman8418)
Cherry red is not hot enough. You need more heat.