David2011
04-23-2015, 11:51 PM
I love my iron and steel molds and have tolerated the aluminum ones for years. Things might have gotten better tonight. I've always fought pace versus mold temperature with the aluminum molds. The 30+year old RCBS furnace drips a little so I wanted to totally drain it tonight to clean the rod and nozzle.
I have six cavity Lee molds for a couple of boolits used in pistol matches where large volumes of boolits are consumed. I've always poured a full stream into the aluminum molds the same as I would for cast iron and steel molds. It's always been hard to get the melt to pile up on the sprue plate using the aluminum molds. The melt just seemed thinner pouring it onto the aluminum sprue plate. I've settled on a pace of pour, let the sprue cool for 10 seconds, dump, let the opened mold cool for 20 seconds and repeat so 1-1/2 pours/minute or so was the average. The mold is the 358-158-RF Flat Nose which leaves almost as good of a hole as a wadcutter but will work at .357 Magnum loads.
As the melt got low in the pot and head pressure diminished the silver stream got smaller. The runaway melt on top of the sprue plate became much more controllable and piled up more like it does on steel sprue plates, stacking up higher but smaller diameter. I decreased the cooling period between pours as I could tell the mold was cooling off until, with a very small stream, the extended cooling period was no longer necessary. I didn't count the time to pour but it was slow, probably 2-2.5 seconds per cavity for a 158 grain cavity where I had been filling the 6 cavities in 4-4.5 seconds with half a pot of melt (22 lb pot). There's an old GraLab darkroom time sitting on the casting bench that really helps regulate pace. The mold had to be kept hot to avoid wrinkles but the pace was greatly increased even though it was taking much longer to fill each cavity. The boolits were looking great and it was the highest quality, lowest effort casting I've ever done with a Lee mold. Next time I cast using one of the Lee six-bangers I'm going to regulate the stream down from the outset and see if the results are repeatable.
Even with the slow fill rate (slower is faster) I cranked out 450 boolits in about 90 minutes.
David
I have six cavity Lee molds for a couple of boolits used in pistol matches where large volumes of boolits are consumed. I've always poured a full stream into the aluminum molds the same as I would for cast iron and steel molds. It's always been hard to get the melt to pile up on the sprue plate using the aluminum molds. The melt just seemed thinner pouring it onto the aluminum sprue plate. I've settled on a pace of pour, let the sprue cool for 10 seconds, dump, let the opened mold cool for 20 seconds and repeat so 1-1/2 pours/minute or so was the average. The mold is the 358-158-RF Flat Nose which leaves almost as good of a hole as a wadcutter but will work at .357 Magnum loads.
As the melt got low in the pot and head pressure diminished the silver stream got smaller. The runaway melt on top of the sprue plate became much more controllable and piled up more like it does on steel sprue plates, stacking up higher but smaller diameter. I decreased the cooling period between pours as I could tell the mold was cooling off until, with a very small stream, the extended cooling period was no longer necessary. I didn't count the time to pour but it was slow, probably 2-2.5 seconds per cavity for a 158 grain cavity where I had been filling the 6 cavities in 4-4.5 seconds with half a pot of melt (22 lb pot). There's an old GraLab darkroom time sitting on the casting bench that really helps regulate pace. The mold had to be kept hot to avoid wrinkles but the pace was greatly increased even though it was taking much longer to fill each cavity. The boolits were looking great and it was the highest quality, lowest effort casting I've ever done with a Lee mold. Next time I cast using one of the Lee six-bangers I'm going to regulate the stream down from the outset and see if the results are repeatable.
Even with the slow fill rate (slower is faster) I cranked out 450 boolits in about 90 minutes.
David