Odd issue with my lee molds

[Gswain]

I have noticed that a couple of molds appear to have a strange condition with the cavities. When the mold is closed, the top and bottom of the mold will be completely flush, no light is visible when held up to a source through the blocks. Yet when I look down in the cavities, it appears that there is a very slight gap in the mold between the halves, almost like the 2 mold surfaces are not completely flat, like they are ever so slightly concave in the middle, running lengthwise down the blocks. I will occasionally, not very often though, get a boolit that has a fin of flashing sticking up on the nose. out of 1 of the cavities. Anyone else seen this?

[stubshaft]

Yup, on a warped 6 cavity Lee 45 mold.

[Gswain]

Hmm, I hear ya but that seems unlikely, I have only used them a few times. How would I have warped it? Never hit them with a hammer, and just use them to cast boolits with a frosted appearance. It seems strange that the tops and bottoms would line up perfectly still if they were warped, just thinkin out loud.

[Wally]

I have noticed that a couple of molds appear to have a strange condition with the cavities. When the mold is closed, the top and bottom of the mold will be completely flush, no light is visible when held up to a source through the blocks. Yet when I look down in the cavities, it appears that there is a very slight gap in the mold between the halves, almost like the 2 mold surfaces are not completely flat, like they are ever so slightly concave in the middle, running lengthwise down the blocks. I will occasionally, not very often though, get a boolit that has a fin of flashing sticking up on the nose. out of 1 of the cavities. Anyone else seen this?

I had this happen to a DC .38 Cal 105 SWC & a .44 Cal 200 RF. I have to run the cast metal hot on these and I suspect that they warped. The .38 Cal has a much larger gap than teh .44 cal...I have since shipped them back to Lee.

[wallenba]

Put them on a hot plate, get them good and hot. Then let them cool. Repeat this a few times and check the gap again. It might need some stress relieving.

[Gswain]

I preheat the molds on a hotplate before I cast, it usually takes 2 pours to turn out perfect boolits. How hot should I heat and cool them?

[725]

As above also, but have you checked the vent lines and other obscure locations for a whisper of lead or other debris that is holding the halves apart?

[wallenba]

I preheat the molds on a hotplate before I cast, it usually takes 2 pours to turn out perfect boolits. How hot should I heat and cool them?

I'm assuming that, if that is your routine, they already have been seasoned and the problem is elsewhere. Lee leaves a lot of burrs all around the cavities, usually on one side of each cavity half. Also on the bottom edge of the blocks and around the pin holes. (moreso on two cavity molds though)

[Gswain]

I do have some lead "staining" on the blocks, but nothing that I can wipe off with a hard piece of oak with a sharp edge when the mold is hot. Just enough to be visible apparently. I have tried getting it off and no such luck so far. Ill take the blocks off the handles next and see if a more detailed inspection turns up anything. What is a common cause of warped molds?

[JIMinPHX]

Pictures?

[Gswain]

Ill get some up next time I get a chance, i cast up at my parents house cause there is far more space.