Help me reduce my rejects please!

[bangerjim]

True. I have always found I need to smoke Al molds (ONLY) the 1st time. Been doing it for years with excellent success. That very thin carbon layer helps in release. Without it, I saw slight hanging and sticking. I use a beeswax candle only, (and light with a BIC lighter!!!) as it gives excellent ultra fine smoke, similar to a lazy acetylene flame.

NO SMOKE for steel/iron/brass molds needed.

banger

[Priusron]

I use a hot plate to heat my mold. I put a saw blade on the hot plate. My mold is a hp mold so has the pins sticking out the bottom. It won't sit flat on the saw blade. I place it flat on the spur plate. I have a can that I cut 1/3 off of and sit that over the mold. I turn the hot plate on high and let it warm. I set my put on 750 with a Pid. I am new to this and I can throw bullets all day with this setup with very few rejects.

[Rattlesnake Charlie]

Ahhhhhh. So many different techniques that work for so many different casters. Science, craftsmanship, black magic, and artistical talent. They all have a place in boolit casting.

[TXGunNut]

I'm guessing this is a new mould. I nowadays give them a good scrubbing with hot water, dish soap and a tooth brush. Then I generally do it again. Then I heat cycle the mould at least three times on the hot plate, letting it cool each time. Then I check sprue plate fit to make sure it fits tight but not too tight. That said, I'll agree that it sounds like your mould was likely too cold. Another thing; sometimes a mould just needs a session or two to break in. I won't pretend to know why that is but when things aren't going well with a new mould after several attempts in the first sessions I put it aside and go on to the next one. After a few sessions it's either broken in or I've finally figured out what it likes, I honestly don't know.

[Le Loup Solitaire]

Thirty percent is too high. Assuming that the mold is squeaky clean with no trace of oil or other petroleum based product, then start with the right temperature (high enough) and 1-2% tin in the alloy. It is not necessary to pressure cast with the spout tight against the sprue hole; a properly regulated stream is sufficient..not a fat oversized one as that will interfere with the air that has to get out of the cavity(ies). Make sure that a generous amount of alloy sits on the sprue plate to feed the shrinkage and not cause voids. A couple of tricks that might be worth trying; 1) drop the mold (when full) about an inch onto a lead ingot placed below the mold....the "jolt" will cause a downward pressure for the molten alloy to fill any voids/bubbles. 2) some casters run the mold back for a second "pour" while the sprue is still molten. These gimmicks take a little practice as they can be kind of sloppy at first, but there is a good chance they can cut down on defects. LLS

[CASTING MACHINE]

Way to high of a temperature for casting. Find a way to make this work at 660-675 f. Are you seeing excess dros in your pot. Constant fluxing and skimming. Keep the heat down and ventilate well you will live longer. I have read somewhere on this site, again i maybe wrong, at that temperature you maybe scorching your tin as well as causing lead alloy to release toxic fumes that at lower temps would not occur. Not sure what elements they were but go to the area and read, really read it through. Read the discussions before you proceed.
When you cast with a high heat, high tin content and use the so called pressure poor method described you are literally forcing alloy the into the venting lines and the parting line. Hence the troubles. LEAD INSIDE MOLD HALVES ETC. Better to have a hot mold with occasional frosting than have all those rejects.

[shoot-n-lead]

Help me reduce my rejects please!

Sure, I certainly will...send them to me and I will shoot them.