What's This, Is There A Cure?

[JohnH]

When I open the sprue plate on my Lyman 379449, the sprue falls away but leaves a half moon shaped flake in the bottom of the sprue countersink. I have to keep this picked off, I use the tip of my screwdriver/mallet to do this. It does not interfere with my casting, prolly keeps me from going too fast and over heating the mold, but man is it annoying. Every 10 or 15 casts, I take a carpenters pencil and mark graffite the bottom of the sprue plate real good around the hole, adn also the top of the mold block, but it don't eliminate the flake, just keeps it easy to remove and keeps it from turning into a lead smear. Thoughts? Suggestions? Knowledge and Wisdom? Better yet, correct diagnosis and cure????

[44man]

As long as the plate cuts the next boolit nice and smooth, it is not a problem. It is normal for a little lead to stay in the hole. Don't worry about it. As long as the cutter is sharp and doesn't tear the lead you are doing just fine.
The only time it is a problem is if you cut the sprue when the lead is still molten. That doesn't have anything to do with a piece of lead in the cutter hole though, just causes smears on the mould top and under the plate. If you don't have smears, cast more boolits and be happy. Leave the little piece of lead alone.

[Sky C.]

Sounds a lot like a small burr. If you have some fine lapping compound - 320grit or better, it might be worth the time to mount a polishing bob in a drill motor and lightly polish the countersink area.

Best regards-

Sky C.

[44man]

Sky, I make my own moulds and the sprue plates are razor sharp with no burrs. I get a little lead at the edge of the hole and it doesn't hurt a thing. It is only lead scraped off the sprue side. Waiting for the sprue to get dead hard will eliminate it but it slows down the casting and lets the mould cool too much.

[JohnH]

Respectfully 44man, defend your position elsewhere. To me this is a problem because left unattended it causes leading. Been there, done that, don't want to do it again. The time it takes to pick it off ain't the issue either, that it forms, and I don't know why or how to stop it is. If I have to pick it off so be it, but I figured that others have seen this problem and resolved it someway, and I'd like to know the what and why of thier solution. Don't worry about it is not a solution. It is in my experience, not normal for a litlelead to stay in the sprue hole/countersink, and every time Ihave encountered it, left unattended it causes leading on top of the mold block. If I was OK with leaving the situation alone, I wouldn't have bothered creating a thread seeking solution. So.... If you have a solution, I'd like to hear it. If you don't, then........

[Buckshot]

...........JohnH, whoa dude 8). 44man's response:

" As long as the plate cuts the next boolit nice and smooth, it is not a problem. It is normal for a little lead to stay in the hole. Don't worry about it."

Prolly based on his own experience, and the fact that you did say in your first post:

" It does not interfere with my casting, prolly keeps me from going too fast and over heating the mold, but man is it annoying."

I too read it as a mere annoyance and not a real problem until your last post. I've had it happen to me and fairly frequently. I have found it forming due to only 2 things. One is that the pour hole doesn't have a sharp edge to cut with. There is a very narrow, but still straight (up and down) section which plows, rather then slices through the lead.

The other cause is a bit of lead smear deposited on the underside of the sprueplate on the side of the hole that does the cutting. As you swing the sprueplate over and across the hot base of the boolit a bit of lead adhears. It may slightly curl up and back into the countersunk hole of the sprueplate.

I have had both happen to moulds regardless of who made it. I will have to be honest and say that Lee moulds have it happen most commonly. I've ignored it and had the stuck material assume a size large enough I'd figure it was interfering with the pour.

In the instance of the blunt sprueplate hole, the remedy is obvious. On the second it always isn't taken care of by tightening the sprueplate pivit bolt. You may have to remove the sprueplate and polish the underside, or polish the spruehole sharp AND polish the plate underside. Sometimes covering the bottom of the plate with pencil lead, mould release, or moly may work.

Bullshop's Bullplate lube also would be a remedy for all but maybe the blunt cutting edge in the sprueplate hole.

..................Buckshot

[JohnH]

My sincere apologies if my post came across short tempered, certainly not my intent. Sounds like I need to get some Bull Plate

[David R]

This is from the 1958 lyman cast boolit handbook. Take a dowel and a small piece of cloth. Saturate the cloth with grinding compound and put it in the sprue hole. Spin the dowl and "sharpen" the sprue hole.

Make a nice even smooth cut. It will help.

David

[44man]

JohnH, no you didn't sound angry and I respect what you say. As long as the plate is smooth and sharp with some bullplate of other carbon on it, the only reason for a build up is trying to cut lead that is still too soft. That is the ONLY reason for smears on top of the mould or under the plate.
The tiny piece I get in the hole is from the same reason. When the next boolit is poured, the new sprue melts the tiny piece and if cooled properly before cutting it, it will be gone.
If it continues to build up for you, you just have to slow down or reduce the lead temperature. You should never have to pick the piece out. Try it next time, if it appears, cast another boolit and WAIT for the sprue to get real hard. It should remove the chunk unless you have actually tinned the plate. If it is tinned, you must stop and clean all the lead off and apply bullplate, pencil or mould prep.
The only way that steel gets tinned is when it exceeds the melting temperature of the lead or by continuing to smear and pack it onto the steel.
The other guys are correct that a blunt edge will cause problems, but this should have been corrected with a new mould before ever casting the first boolit. Your initial mould prep should have included that step.
I have never viewed casting boolits as a race. Casting should be done at a nice leisurely pace that will give the best boolits with the least mould problems. You will find that casting as fast as you can to get the most boolits in the shortest time will actually cost you in mould problems, shut downs and mould cleaning.
Your response puts you into this category and it sounds like you don't want any help.

[nighthunter]

Another thing you may want to try is remove your sprue plate and work the bottom side on a flat sharpening stone. The stone MUST be flat. I keep one on hand that I use only for this purpose.
Nighthunter