Curios issue with Lee Mold

A couple of weeks back I was teaching a friend the basics of casting. We started to have a problem with one of my mods that I have not seen before. This was with a Lee 90310 mold, a 200Gr SWC, six cavity. Normally I drop boolits that are 203 grains, but these were coming out about 205 grains. I am not aware of any change to my alloy. I was using the same recipe, from a batch of 500+ ingots from range lead with some superhard and tin. I have had good luck in the past with this alloy. I did notice that I had to turn my pot up a little, as the weather was about 35 - 40 degrees in my garage that day with the doors open and a fan running. So the boolits were dropping a few grains heavier, and on occasion the mold was not closing all the way, we were getting thin flashing on the boolit where the mold came together. The mold was also occasionally sticking together at times. Together we ended up casting about 2400 boolits that day.

I normally drop my boolits in a 5 gallon bucket of water. While I was not watching my friend after he got going, I am wondering if there was some water that may have splashed on the mold. Normally I may get a drop here or there from boolits droping in the mold, but I am wondering if he may have had some water that splashed on the mold that caused it to warp?

The mold did not appear to be damaged, and a visual inspection did not reveal anything.

How many boolits can one reasonably expect to get from an aluminum mold before it starts to wear out? Or do they not wear out? Any ideas on things that I should check?

Best Regards

any chance that a little bit of lead got on the face of the mold and was not letting it close all the way. would explain the finning and mold halves sticking together. Not sure if it would add 2 grains worth of weight tho. I've got a couple of lee six gangers that have been run HARD ( teaching a friend also ) and are still running fine. ( look like he!! )

Any chance that the pins have shifted and the halves are not coming together or you need to apply lube to the pins? Do you normally cast in those same conditions without issue? A draft and cold ambient temps will affect the mold and sprue plate temp and that might also be a consideration. Is it also possible that the tempo has changed with the other individual being slower and stopping and looking at the bullets instead of just making them and moving right along?

temp makes a difference.

It just may need a good cleaning and lube to come back. Look it over real close with a magnifying glass pay close attention to around the pins blocks junction ( this is a place for crud lead to hide). Pay attention to the faces also as it dosnt take a lot of build up here either to cause problems. Carefully and gently remove any build ups. I use a popcycle stick, bamboo skewers and coarse cloth here. If its lead stuck you may have to heat it a little to help it unstick. Check pin alighnments a to long pin can cause this. I would start with a good dish soap water cleaning then the visual inspection if the problem persists then I would lightly grease or ink one block with bearing blue and mate blocks to see where the highs and lows are.

The key here is having to turn up the pot. Those minor weight differences are probably due to temp differences.

If said friend was holding the spru handle it will cause the mold to flex open.

Quote:

---

The mold was also occasionally sticking together at times.

---

This tells me that the alignment pins are probably the issue. They may be moving a bit, or may just need a small touch of lube.

I have a Lee six cavity that the alignment pins were put in wrong on, they swelled the mold block and it took a long time to figure out just what the problem was. If you measure your heavy boolits, you may find they are out of round by a thousandth or so, which will also point to the alignment pins.

As mentioned holding the sprue plate handle can also cause problems.

Robert