LittleBill
04-11-2013, 07:08 PM
Today at the end of the work day, I stole some time to cast some more boolits. In my last exciting episode, I was getting some strange craters, which some of you opined might be caused by contamination from the sprue plate lube. Now I've got something new going on with the same boolit. In today's session, I was getting slightly rounded bases from time to time. It was not consistent with a particular cavity, nor was it consistent from pour to pour. The mold was nice and hot, and I was getting good fill out for the most part. But sometimes the left cavity would produce a slightly rounded base while the right had a nice crisp corner, and then they would flip, where the left would have a crisp corner and the right would be rounded. And sometimes both would be fine. [smilie=b: I could see a line around the rounded one every time I knocked the sprue off.
After casting a bunch and letting them cool enough that I could handle them, I grabbed my Mitutoyo micrometer and started checking bases. The rounded ones were measuring a scant .452, sometimes .4515. The crisp corner bases were pretty much measuring .453 - .4525. I have some fuzzy photos below of what I observed. In the first one, the boolit on the left is the good one, and the one on the right is rounded every so slightly. In the second one, there are two good ones on the left and two rounded ones on the right. I was getting a good sprue each pour, and the bottom of all the bases look as nice as nice can be. Any ideas from the wisdom here?
http://i119.photobucket.com/albums/o159/FotoBill/roundedbasecolt02_zps5e44554b.jpg (http://s119.photobucket.com/user/FotoBill/media/roundedbasecolt02_zps5e44554b.jpg.html)
http://i119.photobucket.com/albums/o159/FotoBill/roundedbasecolt01_zps9858c003.jpg (http://s119.photobucket.com/user/FotoBill/media/roundedbasecolt01_zps9858c003.jpg.html)
And yes, I know there is a little flash or whatever on the base of the one. It is probably going back into the soup anyway.
After casting a bunch and letting them cool enough that I could handle them, I grabbed my Mitutoyo micrometer and started checking bases. The rounded ones were measuring a scant .452, sometimes .4515. The crisp corner bases were pretty much measuring .453 - .4525. I have some fuzzy photos below of what I observed. In the first one, the boolit on the left is the good one, and the one on the right is rounded every so slightly. In the second one, there are two good ones on the left and two rounded ones on the right. I was getting a good sprue each pour, and the bottom of all the bases look as nice as nice can be. Any ideas from the wisdom here?
http://i119.photobucket.com/albums/o159/FotoBill/roundedbasecolt02_zps5e44554b.jpg (http://s119.photobucket.com/user/FotoBill/media/roundedbasecolt02_zps5e44554b.jpg.html)
http://i119.photobucket.com/albums/o159/FotoBill/roundedbasecolt01_zps9858c003.jpg (http://s119.photobucket.com/user/FotoBill/media/roundedbasecolt01_zps9858c003.jpg.html)
And yes, I know there is a little flash or whatever on the base of the one. It is probably going back into the soup anyway.