Casting with 2 Molds on a Hotplate

I started casting with two molds at once and placing the mold on a hot plate after filling the cavities with lead. So I fill two molds, then I empty two molds, repeat. The temperature of the hot plate is just what was needed for a good preheat.
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The 2nd biggest plus is that my sprue cuts are crazy consistent. The sprue and mold never get so cold that the sprue is difficult to cut, but they cool down plenty fast that I’m not wiping lead across the top of the mold when I open the sprue plate. The sprue cut is not perfectly flat - it does tear out some lead (92-2-2 alloy), but that might-could be fixed by lowering the hot plate temperature.
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The 1st and obvious plus is that my casting is very fast. I’m at roughly 300 boolits per hour (two 5-cavity molds) now and I’m not moving fast. I could actually do this with three molds and get around 400-500 per hour if I moved fast.
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Also, I accidentally left two molds filled for about 5 minutes as I was shutting down my pot and fluxing the oxides. The sprue cuts were the same as all others, and it was not difficult to cut.

Good show glad ya found a effective way thats working for ya!!

CW

I always cast with 2 molds. Just cast fast and you don't need to put the mold on a hotplate while filling the second mold. Heat both molds on the hotplate to begin and go to town. This will not work on the little 22 cal but might work if you put the mold on the hotplate between casts. I only have one 22 cal mold, so I can't try to do it.

I only have one Iron and 1 Aluminum multicavity moulds, they along with all the 2 cavity moulds get used one at a time, I don't worry so much about production rates. Depending on the mould cavity/bullet size volume and which pot I'm using I generally cast about a 3/4 pot with one refill worth of bullets at any sitting.

Single cavity Iron (excluding HP moulds) do generally get paired up for a constant rotation which helps keep down overheating the moulds.
Lee 2 cavity's are one at a time and fast and furious to keep them hot

My iron molds retain heat so well that I always cast with two. And yes--I can turn out bullets pretty quickly without feeling like I'm rushing at all, even with 2-cav molds.

My aluminum molds I tend to just cast with the single mold because they cool down so quickly. I hadn't thought about using my hot plate to keep them warm like you're doing though.

I have cast with at least 2 molds since I started casting on My own back in 1975. No hotplate needed. 2 4cav molds at a time and 2 20lb pots. Empty one, refill and switch to other pot full of fluxed alloy. I cast 30,000 bullets in one long weekend.
Had to take Monday off from work, shoulders really HURT. Never again did I cast that long and hard again.

I warm them up with a hot plate then alternate molds. By the time the bullet is dumped and the mold refilled, the sprue is ready on the other.

+1 ^^^^^^

i use 2 or 3 2 cavity molds .just fill all molds ,let them warm up discard those casts then cast away as fast as you like

When I use 2 molds, I cast with one until it gets too hot, then set it on the pot shelf & cast with the other one setting on the pot shelf. This is generally only with 2-3cav molds.

Quote:

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Originally Posted by MT Gianni

I warm them up with a hot plate then alternate molds. By the time the bullet is dumped and the mold refilled, the sprue is ready on the other.

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Does this work well for you regardless of mold material?
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I’m naturally a slow person and probably not a speed demon filling & dumping molds. I mostly use aluminum and I am thinking of converting entirely to iron (I know brass holds heat better).

It doesn't work so well with aluminum molds because aluminum cools off so quickly. The reason it works well with iron molds is because iron holds heat so well.

Also depends on the size of the mold. Five cavity molds, even aluminum, hold heat well enough that I can keep them at temp running two. But a four aluminum mold, not so much.