Stress relieve moulds?

[Slugster]

I recently purchased two Lee 6 banger Moulds. TL452-230-TC, and 358-158-RF. I have not used them yet as I am heat treating (?) them on my hot plate. Sprayed the moulds with brake cleaner (the correct non-oil bc). Soaked and washed them in water as hot as I can stand, used old toothbrush with Palmolive dish soap. Allowed to dry. Heated them to about 220f degrees and allowed to cool to room temperature twice. Cleaned them again with dish soap and toothbrush. Put them back on the hot plate and heated to appx 400F. Will do this twice before I clean them again.
I have never tried to break in a mould in this manner. I just always accepted the fact that I would have to cast a lot of bad boolits before getting good ones. Giving this a try. Maybe it will stress relieve the moulds and help condition them, or not.
Had to remove burrs on the 452 mould and had to lightly stone the 358 sprue plate because it had material that was dragging on the top mould surface. Going to properly lube the moulds before putting them into service. Will post an update when I have results.

[Larry Gibson]

Mould Cleaning

Forget soap and water.

Clean mould blocks inside and outside and top and bottom of the sprue plate with acetone, brake cleaner or carburetor cleaner (my preference) by simply spraying it on and scrubbing a little with an old toothbrush. Pay particular attention to the cavities.

Let dry, it won't take long.

Now [here's the part where I get yelled at, cursed at and proposed I be banned from the forum] using a propane torch with a medium flame play the flame across the mould, inside and out including the cavities and the top and bottom of the sprue plate. Slowly play the flame back and forth and you will see moisture or oil or whatever come to the surface and evaporate. When it evaporates move the flame on until the entire mould is done. Contrary to popular criticism you are not heating the mould hot enough for anything to warp. Yes, it will be too hot to touch but that's all.

Let the mould cool. When cool I swab the cavities out with a clean dry Q-Tip. I also prep the top of the blocks, top and bottom of the sprue plate and the alignment pins with a graphite mould prep.

That's it. The mould is now ready to pre-heat and begin casting with. You should get excellent bullets within two or three casts. If not, then the alloy probably doesn't have enough tin in it or you are not getting the molten alloy into the cavity quick enough.

I cast with the alloy at 710 - 725 degrees generally, let the molten alloy fill the cavity quickly from my BP Lyman Mag20 and let a very generous sprue form even if some alloy runs off.

I was shown this method many years ago by an old bullet caster. It works on any kind of mould, cast iron, aluminum, or brass. Since I started using this method of mould cleaning I have never experienced the problems many are having. I did have most all of related bad experiences of wrinkled bullets and/or poor fillout even after many, many casts and varying the alloy temp up and down before the use of this method.

[Mk42gunner]

What I do for Lee molds is spray them with brake cleaner, wipe them with a paper towel, then lube with aluminum anti-seize.

I normally don't bother with heat cycling them, my back doesn't let me cast for long any way so by the time I have two to four shortish cycles done they are usually casting fine.

Being an old plumber/HVAC/appliance repair man, I see no problem with Larry's method of heating with a propane torch. I have even been known to use one to heat a lubrisizer to get the lube flowing in cold weather.

Robert

[FLINTNFIRE]

Rubbing alcohol and a toothbrush , put in oven or on hot plate 400 degrees Fahrenheit do it 3 times and cast after pre heating mold , dump first half a dozen casts before checking , I have used a torch but do not over do it , actually acts like smoking a mold along with heating it up , not stress relieving as much as it is conditioning .

[gwpercle]

Acetone and a tooth brush for cleaning ... You want to keep water away from a mould ... water causes the steel parts to rust ... no water .

Follow Larry Gibson's advice in post #2 ... That is good info / advice .

Gary

[Slugster]

Thanks everyone for the tips. I will try Larry Gibsons method with propane torch. Hadn't heard of that, but sounds right. I sometimes use Acetone (out of at the moment) or usually Lacquer Thinner for mould cleaning.