I have one of those infared temp guns I use in another hobby. I decided to see what temp the molds run at when the boolits are looking good.
First try was a Lyman 311644. 190 grain (read long) two cavity mold.
Boolits start to look good at 200 f. Anything under that and they are wrinkled or not filled out. 250 f seems to be the magic number. Once I got near 300 f, they would have crystilization, or not filled out spots in the driving bands. The sprue plate runs around 150 when the mold is at 250 using the bruceB method.
My group buy BD45CM 230 grain 6 cavity aluminum mold.
At first the bottom of the mold was too shiny to get a reading, the infared bounces off it just like a pot of lead. Once I had hit the wet towel with the mold a few dozen times, it got dull and readings could be taken. Same result with the mold, 250f was the temp for good boolits. The spure plate was runing around 300f or a little higher, again using the bruceb method. If I tried to get the sprue cooler, the top of the mold would cool off too. I found this out using the C312 1502R 6 banger. I was cooling the spure too much and the base of the boolits were not filling out giving me too many rejects.
I aslo found with the aluminum 6 cavity filling from the same end first made the mold temp lower at the other end, so now I alternate starting pouring from each end. It didn't seem to make as much difference once I had the mold temp stabilized. Keeping the big alulminum mold consistant was much harder than with the steel mold. It could get down to 200f real easy, or up to 300f if I didin't cool it enough on each pour. It seems less time with the bottom of the mold on the towel than with the sprue on the towel.
Going to try my 452460 4 cavity next.
David
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