StewartLeach
40 Cal.
- Joined
- May 12, 2008
- Messages
- 415
- Reaction score
- 1
I recently began using a two cavity Lee round ball mold, and was initially disappointed with the results. I do a lot of match shooting, and am picky about ball quality. Balls are hand inspected for obvious flaws, then weighed. Balls more than one half the standard deviation from the mean are rejected. Stats are based on samples of fifty or more balls from each mold.
I have had excellent results from Lee single cavity molds, and was surprised at how many from the two cavity mold went into the re-melt can. Began to think it was my technique rather than the mold. Casting one at a time- only filling one chamber- produced good balls. Had to be me!
I had been casting by filling the chamber farthest from the handles, then moving the dipper spout over to the near chamber. Keeping an eye on the balls as they fell out and sorting revealed the second ball was often poorly formed and light.
Tried a second technique- hold mold vertical, dipper spout placed at sprue hole, then rotate to fill, then tilt vertical again and move dipper to second chamber. Number of visual rejects and weight rejects went down, but still higher than results with single cavity molds.
Third technique was to hold mold vertical, tilt and fill first chamber, then return dipper to pot for a fresh load of metal to fill the second chamber. Excellent results, in line with single chamber mold.
My theory is that in the first two techniques the dipper of metal cools just enough while filling and overpouring the first chamber that it isn't hot enough to flow properly into the second chamber.
The two scoops of metal and individual pours technique is slower than one filling of the dipper, but only opening the mold once for two balls and the lower reject rate result in higher net production than with the single cavity mold.
Comments please!
I have had excellent results from Lee single cavity molds, and was surprised at how many from the two cavity mold went into the re-melt can. Began to think it was my technique rather than the mold. Casting one at a time- only filling one chamber- produced good balls. Had to be me!
I had been casting by filling the chamber farthest from the handles, then moving the dipper spout over to the near chamber. Keeping an eye on the balls as they fell out and sorting revealed the second ball was often poorly formed and light.
Tried a second technique- hold mold vertical, dipper spout placed at sprue hole, then rotate to fill, then tilt vertical again and move dipper to second chamber. Number of visual rejects and weight rejects went down, but still higher than results with single cavity molds.
Third technique was to hold mold vertical, tilt and fill first chamber, then return dipper to pot for a fresh load of metal to fill the second chamber. Excellent results, in line with single chamber mold.
My theory is that in the first two techniques the dipper of metal cools just enough while filling and overpouring the first chamber that it isn't hot enough to flow properly into the second chamber.
The two scoops of metal and individual pours technique is slower than one filling of the dipper, but only opening the mold once for two balls and the lower reject rate result in higher net production than with the single cavity mold.
Comments please!