The tin can lead casting.

[David2011]

Best wishes with your health issues.

Someone once gave me some wheelweight ingots that wouldn’t make good quality bullets. There were lots of inclusions in the cast bullets. After stirring about 2 tablespoons of sawdust into 20 pounds of melted alloy the bullets came out clean and perfect. Leave the sawdust ashes on the melt to slow oxidation. It probably shouldn’t have to be said, but don’t use sawdust from treated wood.

 

[Larry$]

I do casting, mostly aluminum & its alloys. Always outside. There is no way of knowing what might be in the scrap metal! I have flame retardant boot covers, gloves & chaps plus a full face shield. Be really careful around anything that contains moisture as it can cause instant steam explosions. That includes concrete surfaces. I've tried pour into cans to get cylinders to machine but the hollow that forms from shrinkage makes for to much lost metal. Sand or lost foam casting is pretty easy.

 

[RJSakowski]

An old thread but I didn't see the original question about the central hole answered. The reason for the hole is that the outer regions cooled and solidified while the center was still liquid. As the metal froze and shrank, it pulled metal from the center creating the void. There are two ways to remedy this. One is to put the newly melted pour in its tin can mold into a bucket of ashes which will provide a more uniform temperature throughout the casting and hopefully provide for it all freezing simultaneously. The second is to reduce the temperature of the molten metal to slightly above the melt point. This can be done by melting at a higher temperature and then holding at the lower temperature for enough time for the casting to equilibrate. Actually, I would do both.

 

[graham-xrf]

An old thread but I didn't see the original question about the central hole answered. The reason for the hole is that the outer regions cooled and solidified while the center was still liquid. As the metal froze and shrank, it pulled metal from the center creating the void. There are two ways to remedy this. One is to put the newly melted pour in its tin can mold into a bucket of ashes which will provide a more uniform temperature throughout the casting and hopefully provide for it all freezing simultaneously. The second is to reduce the temperature of the molten metal to slightly above the melt point. This can be done by melting at a higher temperature and then holding at the lower temperature for enough time for the casting to equilibrate. Actually, I would do both.

I took the brutally simple approach! After the first failed melt, I heated up again, this time over a cheap portable camping-style stove. I also heated it additionally from the top using a propane torch of the sort usually used for soldering plumbing pipes. I also added in some cut up bits of candle, and then stirred it about about until no more dross came to the top. This whole scene is smelly, dirty, messy!

During cooling, when I saw the void hole happening, I "assisted" with the torch by heating from the top, ensuring there was always molten lead coming in from the sides, and keeping the hole filled. It all took only a few minutes.