Mould temperature

[GregLaROCHE]

I just finished casting twelve pounds of lead in my new Lee 405 gr mould for my .45-70. I have casted .30 cal in a single mould and never had any problems with the mould getting too hot. Today I guess with the big bullets and double mold things were heating up fast, even though it was just above freezing.

I first realized it when the sprue was very thin just covering the plate and not joining the two together. I cooled the mould down and things went back to nornal, but it soon heated up again. I tried lowering the temperature of the lead, but that didn’t make much difference. The interesting thing is when it was hot I got some of my best boolits.

Is there anything wrong with working with a very hot mould? Will it effect the quality of the boolits or damage the mould? I am working with almost pure lead.

Thanks for your ideas and input on this.

[lightman]

Bigger bullets mean less material in the mold. Sometimes you have to make yourself slow down. Some casters use this time to run another mold. Your biggest danger is going to be getting a lead smear on top of the blocks if you cut the spru to soon. Temp can have minor effect on bullet diameter.

[JonB_in_Glencoe]

When a mold is hotter than it should be, depending on how soon you cut the sprue, you can get lead smearing on the sprue plate, and that can build up near the sprue plate mounting screw and can cause galling on the aluminum mold blocks.

Another factor if you are dropping boolits that are so hot that they aren't totally frozen, you can get fractured boolits.

I would suggest using a small fan. When I cast large size boolits, I use a small 6" desk fan, it sits right behind the lead pot and is aimed toward the area I am dropping the boolits. It cools the pile of boolits, as well as the mold, you can gauge the amount of cool down by how long you hold the mold over the pile of boolits.

[Grmps]

+1 on multiple molds.
When I cast large boolits, I usually run 2 or 3 molds.
Another problem with cutting the sprue to soon is you get a divot where the sprue pulls a chunk out of the boolits base

[GregLaROCHE]

When a mold is hotter than it should be, depending on how soon you cut the sprue, you can get lead smearing on the sprue plate, and that can build up near the sprue plate mounting screw and can cause galling on the aluminum mold blocks.

Another factor if you are dropping boolits that are so hot that they aren't totally frozen, you can get fractured boolits.

I would suggest using a small fan. When I cast large size boolits, I use a small 6" desk fan, it sits right behind the lead pot and is aimed toward the area I am dropping the boolits. It cools the pile of boolits, as well as the mold, you can gauge the amount of cool down by how long you hold the mold over the pile of boolits.

You are right. I did have to unscrew the spru plate once to remove lead. I didn’t have a fan but the temperature was around freezing and there was a light breeze. I cooled the mold several times as Lee says, on a wet sponge, however it didn’t take long to heat back up. I was also dropping them in water to harden them a little.

I wish I had more molds, but I am just getting into casting and have to stay within my weekly budget. I have one of those things called a wife and if I spend too much at a time I’ll catch Hell! I have ordered two new molds, but have kept silent about it. Easier to get forgiveness than permission.

In the beginning it sounded like casting boolits would be cheap, but I am sure spending a lot getting set up. Now I have to think about bullet sizers if I really want to be accurate they say. Oh well, you have to find passion in life somewhere.

[Uncle Grinch]

I picked up one of these infrared temperature guns to monitor my alloy and mould temp. With it I can make adjustments in my pot temp and mould temp.

[bangerjim]

I picked up one of these infrared temperature guns to monitor my alloy and mould temp. With it I can make adjustments in my pot temp and mould temp.

IR guns do NOT accurately measure the temp of shiny surfaces. They are based upon “black body” raidation technology and need to be pointed at dull/dark surfaces. You can float a black oxide washer on your melt and shoot that. You can use BirchwoodCasey Aliminum Black liquid to darken one end of your Al molds. Yes you can get a reading but in my research, that reading will be off possibly many degrees from the actual process temp.

[GregLaROCHE]

I picked up one of these infrared temperature guns to monitor my alloy and mould temp. With it I can make adjustments in my pot temp and mould temp.

I have one of those guns, but when I used it before it didn’t seem accurate. It always seemed too low. I use a lot of flux, sawdust, and I think the difference above and below the flux is quite different.

My question is, do I risk damaging anything like the mold and could I have problems with the boolits? Voids inside, a lot of shrinkage etc.

[aap2]

Many of my molds (especially HP) cast best when run hot, almost to the point of frosty boolits. Running multiple molds helps getting the sprue to freeze, but a real timesaver has been using a small manicurist fan to help cool the sprue puddle.

[bangerjim]

I have one of those guns, but when I used it before it didn’t seem accurate. It always seemed too low. I use a lot of flux, sawdust, and I think the difference above and below the flux is quite different.

My question is, do I risk damaging anything like the mold and could I have problems with the boolits? Voids inside, a lot of shrinkage etc.

You're not gonna damage a mold unless you drop it or bang on it. Too cold mold will yield possible voids and hard-to cut sprues.

[Rcmaveric]

I just used my first single cavity mold three days ago. It took me a day of watching the sprue for it to tell me how to cast with it. I had to use a second mold with it. That sprue is very telling. I noticed that if the sprue stays liquid for a second and surface tention made the liquid lead have a nice bubble. Then set that mold aside to to coll and grab the other mold. The sprue cuts by hand with a crisp pop off the second mold. I dump it and refill the mold. Set that mold down. By that time the other sprue had cooled to a dull grey with a niddle pin in the middle. Repeat at process between molds. I got the tempo pretty fast last night. Those bullets were the prettiest and shinniest i have ever casted. I noticed that if the pot spout froze or the sprue froze too quick then the bases would be deformed. If i let the mold cool without out a bullet in it the the sprue plate would be too cool and cause the bullet to he frosted with out the base filling out.

Other note, my allow is also 50/50 range scrap and coww. Very little to almost trace tin content. So the pot temps needs to be a little higher and the molds ran hotter to get good fill out. I am sure thay if add a percent or two of tin then i wouldnt have needed to run so hot on the edge of frosting and changed my steps and process.

Nothing wrong with frosted bullets either, but there is a pride and beauty factor.

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