Evenly heating aluminum blocks?

Seems like no matter how I heat the blocks, once I start getting good fill out, the edges of the lube grooves look too hot. They’re so heavily frosted, the edges are indistinct and look rounded, like they didn’t fill out completely, while the nose & base may not be frosted at all.

I’m guessing that’s because the shoulders that form the grooves are where metal is thinnest, so that’s where the blocks get hottest.

I cast with either COWW + 2 or 50/50 Pb/COWW+2 with the PID on my Pro Melt 2 set at 730.

The blocks get hottest near the sprue plate since the steel retains heat more than Al. Lee cuts away some of the block at the nose so this can aggravate things.

I use a wet towel to control mold temp. Touch the bottom if the nose is too hot or sprue if base is too hot (do this after pouring and before cutting sprue). A couple seconds is all it takes. Once I get good fill and surface I note how long to cool the top and/or bottom. The longer the bullet the more of a difference there can be.

I have found that good filliut woth otherwise frosted and rounded bands between the lube grooves has been due to a too small sprue and the sprue cooling before the boolit. I have remedied that by pouring a very large sprue, sometimes ends up running off the back of the block/sprue plate.

This is especially true with larger bullets.

I am using a bottom pour pot.

I also believe this is why ladel pouring is so successful. The sprues are never small.

Brad

I've only got a couple of Alum. molds.
I have to run the pot a little on the hot side for them, and as said, make a large sprue puddle.

Alternate your casting with two molds. Pour let it set, then break the sprue on the other mold and empty. Pour, let the melt set and break the sprue on the other mold. You're not letting things set enough or in other words, your cadence is too fast.

WIth my alum molds, I find a small fan helpful for cooling them when they start getting hot. Just open the mold & hold it in front of the fan for 30sec or so. The other option is cast with two molds alternating this keeps the mold from over heating.

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Originally Posted by Jtarm

Seems like no matter how I heat the blocks, once I start getting good fill out, the edges of the lube grooves look too hot. They’re so heavily frosted, the edges are indistinct and look rounded, like they didn’t fill out completely, while the nose & base may not be frosted at all.
I’m guessing that’s because the shoulders that form the grooves are where metal is thinnest, so that’s where the blocks get hottest.
I cast with either COWW + 2 or 50/50 Pb/COWW+2 with the PID on my Pro Melt 2 set at 730.

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Maybe I'm missing something, but I pre-heat the Lee alu mold resting on the top of the 10 or 20 lbs. bottom feed Lee electric pot while the alloy melts, at max temp._
when the bullets come out shiny, often at the beginning, the edges tend to be imperfect and rounded_
when I have frosted bullets the filling is generally optimal and the edges are sharp...

Here’s a sample from tonight’s session.

This is from a four-cavity Accurate mold, 43-219:

https://uploads.tapatalk-cdn.com/202...c0d1978c38.jpg

Mold opening to soon.

I'd also say not hot enough.

Mold not up to temp and dirty. I see no frosting.

I set all moulds, even iron and steel, on a 5th burner sprue plate down and pre-heat them slowly on about a medium setting, as soon as I start the pot. Even on a brand new mould, usually the first pour is a perfect cast.

Mold too cold, are you pre-heating on a hotplate. If so set the temp a bit higher, if not suggest you invest $20 in a solid surface hotplate, got mine some time ago from Wamart and haven't had any pre-heating problems since.

The meplat edges look almost sharp. Your bases don’t look horrible. The lube grooves are by far the worst and from my phone looks like the poor fill out has a rough texture. Check the lube grooves of your mold. I’ve had lead stick there when I tried speed casting with two Al molds. It was very difficult to remove and would tear lead away from the next boolits cast.

For my aluminum molds I let it float on the lead for a count of 20 to 23. one thousand and one, one thousand and two. The second pour comes out good.
After about 10 pours I also lay the mold sprue down for 3 or 4 seconds on a small wet cotex shaped pad of cloth and the sprue plate does not pull any lead out of the base. Been doing this for years with RCBS, NOE aluminum, and Acc Molds aluminum molds.

On the original post: rounded/defective lube groove corner -- think I would clean the blocks at the lube groove particularly. Q-tip and brake cleaner / gun scrubber.
Also possibly too cold of a mold in general.

On the general heating of the blocks: I set the mold on top of the melted lead in the pot, until the lead will not stick to the mold base any longer. I myself don't find a need to time it.

Don't forget to heat the sprue plate. Sprue Must solidify Last to get good bullets.

Before I set the mold on the melted lead I wipe the sides and bottom with a rag that has some WD 40 on it. This to prevent the lead from sticking to the outside of the mold. If any lead is sticking to the mold it comes by brushing it with the rag.