I have a 20 pound Lyman lead pot that I have upgraded to a home built electronic temperature controller. This works so well it is scary. +/- 5 degrees F is very east to maintain. The probe is calibrated via the software so that the top of the melt and the bottom of the melt are the same temperature.
The problem I have is that the the bottom pour drain keeps cooling and blocking the flow of the alloy which is at it's ideal melting temp of 680 Degrees F.
If I crank up the temp above 725 degrees my alloy separates and no amount of fluxing / mixing will prevent it from doing so. The cast bullets at this higher temp are frosted as well.
The drain is very close to allowing a flow and a one second blast of torch heat will free it all up again,only to happen a couple of minutes later.
The melt is not clogged with crud,it has solidified due to being cooler than the lead in the pot. The drain and its valve are cooler than the melt.
I'm using a bullet ladle now from the top and it works just fine. The sprue is larger than I'd like. The bottom pour has very little sprue when used.
I'm open to any helpful ideas you may have on how to not overheat the melt, but have the bottom pour drain not solidify up ?