Whistler
07-13-2010, 03:53 AM
It was a fine evening and I just got back home from the gym after a day's work.
Two brand new Lee six cavity molds where just lying on my desk at home. There was still some daylight left, so I packed my gear and went off to my local club for some casting. It ain't easy living in an apartment when casting and reloading...
I heated up the pot. I cleaned both molds thoroughly with alcohol and then sooted them with a carbide lighter. I let the molds heat up on a heat plate that I know would do right. I waxed the pivot points. By now I had a fine melt.
First pour turned out six perfect 358-105-SWC. Beautiful boolits, I know that my 9mm will love them.
I took the second mold from the plate, a TL452-200-SWC. Second pour turned out... What? A deformed mess of something that might have passed as a boolit with some imagination. There were wrinkles and voids all over. Tried it again. Better luck, the wrinkles were smaller. Once more, even smaller.
I got it down to where there was a clear lack of fillout just where the two halves of the mold met, but there was something weird - the void was on the same spot each time, but always different cavities!
It took me the better part of an hour before I had singled out what was wrong. Even the slightest amount of tilt trapped an air pocket underneath the sharp shoulder of the SWC design. I then tried to see what could affect it, what could be done to avoid it and what techniques could cause it. I was left with three options:
1. Wiggle and twitch the mold while pouring, so the melt would fill out everywhere.
2. Tilt the mold nose down, then nose up for every fill on every cavity.
3. Keep the mold exactly horisontal and pour straight from above into the sprue hole, stopping the pour between every cavity as to not let any melt run from the sprue plate.
I use wheel weights only, so I guess I could get better fillout with some tin, but since I melt the weights in my Lee 20lb pot, I think I would have problems with differences in alloy if adding tin on random.
If this had happened on any other day I would probably have sent the mold back to Lee. I own about ten of their six cavs and they are all very easy to cast with. Luckily I was in a curious mood, which lead me to experiment. All molds are individuals, and this one turned out to be a bit finicky. Luckily it won't be the one I'll shoot the most, so I can lay down the extra time it takes to get a good fillout on each pour.
Two brand new Lee six cavity molds where just lying on my desk at home. There was still some daylight left, so I packed my gear and went off to my local club for some casting. It ain't easy living in an apartment when casting and reloading...
I heated up the pot. I cleaned both molds thoroughly with alcohol and then sooted them with a carbide lighter. I let the molds heat up on a heat plate that I know would do right. I waxed the pivot points. By now I had a fine melt.
First pour turned out six perfect 358-105-SWC. Beautiful boolits, I know that my 9mm will love them.
I took the second mold from the plate, a TL452-200-SWC. Second pour turned out... What? A deformed mess of something that might have passed as a boolit with some imagination. There were wrinkles and voids all over. Tried it again. Better luck, the wrinkles were smaller. Once more, even smaller.
I got it down to where there was a clear lack of fillout just where the two halves of the mold met, but there was something weird - the void was on the same spot each time, but always different cavities!
It took me the better part of an hour before I had singled out what was wrong. Even the slightest amount of tilt trapped an air pocket underneath the sharp shoulder of the SWC design. I then tried to see what could affect it, what could be done to avoid it and what techniques could cause it. I was left with three options:
1. Wiggle and twitch the mold while pouring, so the melt would fill out everywhere.
2. Tilt the mold nose down, then nose up for every fill on every cavity.
3. Keep the mold exactly horisontal and pour straight from above into the sprue hole, stopping the pour between every cavity as to not let any melt run from the sprue plate.
I use wheel weights only, so I guess I could get better fillout with some tin, but since I melt the weights in my Lee 20lb pot, I think I would have problems with differences in alloy if adding tin on random.
If this had happened on any other day I would probably have sent the mold back to Lee. I own about ten of their six cavs and they are all very easy to cast with. Luckily I was in a curious mood, which lead me to experiment. All molds are individuals, and this one turned out to be a bit finicky. Luckily it won't be the one I'll shoot the most, so I can lay down the extra time it takes to get a good fillout on each pour.