mold problems come up

[Kevin Stenberg]

I have a 2 cavity NOE aluminum mold that i have started having problems casting with.
The cavity closest to the sprue pivot pin. Always leaves a raised sprue cut. And there was a very slite flashing around the base of the bullet. Today i was only casting with that cavity. I was cutting the sprue just prior to puddle freeze. And varying down pressure when cutting the sprue. But about 50% of the bullets had the raised sprue nub.
On the other cavity i was getting a lot of flashing under the sprue plate. About 80% of all bullets had flashing. I loosened the sprue bolt which helped lessen the flashing. But there was always some flashing.
The only fix i can think off is to hone the top of the mold and bottom of the sprueplate.
The sprueplate was loose enough it easily pivoted on its own weight.

 

[Ben]

The sprueplate was loose enough it easily pivoted on its own weight.

Sounds like you need to tighten up the sprue plate.

Ben

 

[KeithB]

And make sure there isn't a little smear of lead on the sprue plate under the pivot screw area.

 

[Jeff H]

I know NOE has pretty hefty sprue plates, but I've warped LEE 2C steel sprue plates, which are not quite as hefty.

Had that last winter on a LEE 2C 358158RFN and with the exact same symptoms. The plate humped up in the middle - touched the top of the blocks on both ends. Neither tightening nor loosening the sprue plate helped - had to "tweak" it and lap it to get it to behave.

 

[Rex]

On my old Ideal steel moulds I leave the cutter loose enough to swing by it's own weight. If I get a nub on the bullet base I need to heat the cutter up a bit more. Don't know about aluminum, I don't have much luck with them.

 

[fiver]

you have to set the tightness on both ends of the NOE plates.
you want it to swing over the mold with a hint of friction and then lock under the second [non swing] screw with a little friction so that you need a hint of lube on the plate right there for it to work smoothly.

hold the mold up flat and aim it at a back light and you'll see the unevenness.
set the screws so the plate is flat when closed.
one screw tighter or looser than the other will put uneven pressure on the plate causing your problem.