9mm mold misalignment

Melnic · Nov 26, 2014

OK,
Got in a 9mm mold last week and had some time before work so fired up the casting pot.
Warmed up the mold, cast about 4 pairs dumping back into pot then went to down. Then about 30 into it, I noticed flashing coming from the top. Tightened the top screw and still kept going. Grabed some samples and put it all away and took samples and mold to work.
Here is what I found. Pins backed out or were not properly aligned. I think they backed out cause I did not noticed this when I was smoking the mold.

bigalf · Nov 26, 2014

Thats weird. I have some of the Lee molds myself, but never had that issue. If you want some real expert advice, post over at http://castboolits.gunloads.com.

Melnic · Nov 26, 2014

Reading previous threads on the CB website, I found this has happened to others. Then was pointed to this FAQ on the lee site:

Alignment Pins Fall Out- Overheating Double Cavity Mold
Posted by Steph @ Lee Precision on 11 February 2014 01:32 PM
We made a change to the alignment pin system in 2012, and have produced and delivered tens of thousands of the new style molds. have received glowing reviews and almost complete satisfaction.

The maximum operating temperature should be limited to 400 degrees and the absolute maximum of 450 degrees for a maximum of 30 minutes. At 450 degrees the pins will turn a Pale straw-yellow. Any temperature above this will excessively reduce the tensile strength of the aluminum block by annealing. Once this overheat occurs the only repair possible is replacing the pins and cups with suitable oversize pins.

The aluminum molds will not overheat by simply casting but can be overheated by preheating with a hot plate, torch, setting on top of the pot to heat up or immersing in molten alloy for an excessive amount of time.

I did not torch my mold. I did pre-heat it by dipping into the molten lead.
450 max, wait I guess they mean 450C (842F)?

Maybe My pot was too hot?

Trigger Time · Nov 26, 2014

That's interesting because the bullets don't look frosted like a too hot mold would cast.
Maybe Lee will give you a replacement?

Blacksmith101 · Nov 26, 2014

The maximum operating temperature should be limited to 400 degrees and the absolute maximum of 450 degrees for a maximum of 30 minutes. At 450 degrees the pins will turn a Pale straw-yellow.

They are talking about 400 F and 450 F. Steel like the pins are made from will permanently turn color as the temperature increases, these are oxide colors that are specific to certain temperatures.

Here is a list of temper colors:
http://www.anvilfire.com/article.php?bodyName=/FAQs/temper_colors_hardness.htm
A photograph
http://commons.wikimedia.org/wiki/File:Tempering_colors_in_steel.jpg

It looks to me like your pins are a darker than what I would call pale straw-yellow which means they have been heated to a higher temperature. This could have happened during the preheat and the damage was already done before you started casting even though your alloy temp was correct for the casting. The melted lead is much hotter than 450 F but because of conduction and convection the mold wont reach the same temp as the alloy poured in.

Because aluminum and steel expand at different rates the steel pins will get loose because the hole they are press fit into expands more than the pin. That level of heat has changed the factory heat treatment of the aluminum blocks. I suggest you call Lee Customer Service and see what they say. If they tell you to return the mold send a couple of bullets with it so they will understand.

9mm mold misalignment

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