Mold help...

[scion19801]

How do I get this issue to go away? I'm having a sprue plate issue with the sprues cutting cleanly. Every cut I make it is pulling the base of my slugs out of round on the .249-rf NOE mold. I have flat sanded the bottom of the sprue plate. tried a few times to re-chamfer to make sure there is no visible lip in the sprue plate opening between the chamfer and bottom. re-sanded to ensure perfectly flat. I wait a 5 count after sprue freezes over and it pulls half-moons on the right lower corner of the slug base to where you can see a clear black outline. I have tried cutting when the sprue is still molten, and it still does it. Wait longer after complete sprue freeze over and it gets even worse, and harder to cut. LOL. Grr.

[Loren]

Add some Antimony to your alloy.  It will bring up the compression strength of the alloy and help with the deformation.  I would start with 1/2% and work up from there by 1/2%.   Maybe 3% max so you do not get too hard.  You could do the same with Tin.

[scion19801]

this is pure lead. so a bit might not hurt. i also just flattened the top of the mold so now spure plate is flat and mold top is flat. the half-moon side was higher that the other side. so i'll keep playing and see how it goes with mold back up to temp. I tried pressure pouring thinking maybe it was due to mold not filling out all the way. but no change there.

[sb327]

It appears as though the pour hole is a little large for caliber. Unless I’m seeing the image wrong.

Dave

[Greg_E]

I would question whether the edges of the cutting area were dull, but I think you already sharpened things up. Next I'd think the sprue plate was bent at the screw location allowing the plate to ride a little high. Since you have now flattened the mold and the plate, not sure what else could be an issue

[triggertreat]

Some thoughts are to loosen the sprue plate bolt just slightly more and lower the pot temp to a range around 740° to 760°.  I will say the sprue hole edge is critical for a clean cut and they can become fouled up.  I use a perfectly fitted slot head screwdriver to periodically keep the hole's cutting edge clean.  One other thought would be the brass holding hotter temps on long runs.  Touching the mold to a damp sponge or cloth will help to bring the temp back down.

[scion19801]

measured holes. the one hole next to handles in sprue plate is. 155" the second is .166" hmm. This is a .249 mold. for .25 cal. I run my lead temp at 800 *F. seems to always give me the best-looking slugs. By best looking I mean no wrinkles or craziness. Any cooler and I get wrinkles and blobs.  Also, pid controlled with in the pot K-type probe. And correct this is a brass 2 cav.
I cut my molds with a pig skin gloved tig welding glove and my hand rarely feels the heat of the mold. I don't like to mallet my sprue plates open. they snap open fine with a gloved hand, and it allows me to keep mold heat in check.

[Wayne52]

Both sprue plate holes on mine measure .138", I'd see if they might have one you could get from NOE because those holes are too big IMO.

[maraudinglizard]

Both sprue plate holes on mine measure .138", I'd see if they might have one you could get from NOE because those holes are too big IMO.

I have to agree with Wayne, those sprue holes are to big for the size slug you are casting.

[scion19801]

hmm, i think i got a damaged pellet 2 cavity brass mold i could possibly swap sprue plate off and see if it works or not. Now to figure out where i put that mold.

[sb327]

We like to think that sprue plates cut but in reality, they kinda cut/break/burnish. Look at about any sprue plate and the bevel seldom goes all the way through to create a sharp edge.

This can be evident by the little broken out piece in a lot of bullet bases.

Dave

[Greg_E]

The worst of mine got sharpened in the direction of cut and works better now. But I also noticed last night that it can oval the bullet at the "cut" point. I wrecked that entire batch while sizing (still not sure how) and they all went back in the pot to try again. This was a steel Lyman mould, rarely do I see this with my Lee molds.

[scion19801]

Found my other mold. It has sprue holes in the .145" range, and both are the same. Gonna fire up the pot and see what happens. More in a few hours on if this fixes the pulling in my bases. I hope it does. Being they are both two cavity molds the hole centers do line up. Awesome job that NOE does on their molds.

[scion19801]

ok, we're on to something now. the smaller sprue hole is improving the bases and less pulling. the half-moon issue is smaller. But now the mold wants to be force-filled. which I'm fine with. I now wonder if we drop the spue hole down further yet if it will eliminate the pulling all together. so, I've dropped around .01-.02" in sprue hole diameter, would another .01"-.015"-maybe even .02" totally eliminate and the cause a definitely pressure fill only situation but give perfect bases? Could possibly be even a cavity venting issue as to why it now wants to be force fed versus just direct bottom pour into the hole from a 20# pot.

[triggertreat]

Just a thought from when I was fighting this same issue.  One thing I did was to flip the plate mount around to the other end.  I definitely saw different results.  I did this mainly because of being a lefty though.

[sb327]

I pressure pour with a ladle only. One thing with the smaller holes is the sprue plate needs to be kept HOT. I generally allow quite a bit of lead to pour across the top as I remove the ladle.

The smaller the caliber, the more difficult they can be.

If you were having good fill out with the larger hole, venting is probably not the suspect. Although more venting may help.

Dave