Troubleshooting Casting Defects

[justindad]

Is there a thread with examples of different casting defects, and how to resolve them? Maybe some guidance on what imperfections are acceptable for plinking?

My first session today gave me 95% reject rate due to rough surfaces, with a few wrinkles too. I might be too picky on the rough surfaces.

[44Blam]

Wrinkles are normally too cold or an oily contaminate...

[WheelgunConvert]

The 3 best lessons I had to learn:
1. Mould cleanliness is critical
2. A clean mould is worthless if it is not hot enough.
3. It’s a hobby, keep more and shoot’em anyway. Don’t lose the enjoyment in your long term pursuit of improvement.

[GregLaROCHE]

Clean the mold thoroughly to make sure there is no trace of oils that can cause wrinkles. Is there any tin in the alloy? It helps to get a better fill out. Flux well. Make sure the alloy and mold are hot enough.

If you post some pictures maybe we can give you more detailed advice about your problems.

[Wayne Smith]

And go to your profile and add a location. One of us may be close.

[justindad]

Alloy is 92-6-2 Pb-Sb-Sn from Missouri Bullet Company. Mold is new 358-124-TC-R4 5 Cavity PB from NOE. I did the 350F warm-cool cycle three times and then deposited carbon inside the cavities with a Bic lighter, following instructions that came with the mold.

In my shame, I melted my mistakes. Too bad I can’t do that in real life

Next time I’ll use the thermometer, and see if I can get smoother parts at some temperature around 350F.

FWIW - the roughness was like pitting, not like frosting. I don’t see colors in the pitting to indicate debris inclusions, but they could be really small.

[onelight]

What defects are acceptable for plinkers for you is your choice . I see a lot of cast that I would have put back in the pot. One of the reasons I started casting was the commercial cast bullets in the gun stores at the time had rounded driving bands , and other defects most leaded at even low velocity .
So for me almost any visible defect goes back in the pot even for plnkers .
Your choice choice I do make compromises on my short range 7 to 25 yard plinking ammo that I would not make on long range or hunting or cary ammunition .
One thing that seems to have an impact on how easy it to get good bullets is the bullet shape the fewer 90* corners on the bullet the easier it is a round nose bevel base is easier to cast , but l prefer Kieth style for my best.

[Dusty Bannister]

It sounds like your alloy should not be the issue. As long as you did not have junk alloy in the pot to begin with. What is the melt temperature? I cast conventional lube groove bullets at about 720F and do not cast HP bullets. But I do understand they need to be cast at a higher temperature since there is a lot more metal acting as a heat sink, so the melt cools too rapidly. I do not know if the carbon coating is an issue, but if you wipe it off with a clean Q tip and things do not improve you can always lightly apply it again. The purpose of the carbon it is speed up the break in of the mold.

Common problems. Incomplete fill or creases on the sides of the bullet. Mold and alloy not hot enough. Incomplete filling around the HP pins, Need more heat and a fast pour. Pitting with debris is dirty alloy or pot residue. Pitting without residue, still giving off oil vapor and not enough heat/time in the break in cycles. Round base casting, venting issue or pouring too slowly or missing the sprue hole. Will wait to hear what other issues you might have.

When you can provide photos, please show the nose, sides and bases so we can get an overall view of the problems you have encountered.

[GregLaROCHE]

350* seems a bit low.

[high standard 40]

You might try removing the smoke residue from the mold cavities. I have about 20 molds, aluminum and iron, 22 through 45 caliber, and not one of them needs smoked cavities to produce excellent bullets.

[Hossfly]

Get a hot plate and get your mold up to temp before casting. I get up to at least 400+ then over fill mold and let soak for a few seconds, before doing a run. This gets everything good and hot, pretty quick, then keep up your rhythm. Any oils should be out by then. I start casting at 725-750 and try to maintain that temp, easy with good PID control. Good thermometer makes a difference.

[popper]

Way to low temp, even 350 C is only 650 F and barely liquid. That alloy needs to be 730 F or so. Something big wrong with temp measurement?

[Gator 45/70]

Zn or Zinc is not you're friend

[mdi]

Not sure of my memory this morning, but other members can correct me if I'm wrong. IIRC the Lyman Cast Bullet Handbook has a trouble shooting section with pictures of defects and reasons for flaws. More than likely the 3rd Edition as I used it much more than the 4th.

My standards are pretty tight because I have plenty of time. I only have one 6 cavity mold as most are 2 cavity and perhaps your 5 cavity mold is adding to the culls because mold temp can vary from one end of the mold to the other. Rough finish can be from the carbon from smoking and frosting normally from high heat. I haven't found minor wrinkles to be bad for accuracy so I let some slip by. For me the most important "standard" is sharp corners on a flat base. Next is sharp corners on driving bands, grooves. And I don't like those tiny black "spots" from dirty alloy so I clean and flux often....

Like I said these are my requirements and some others will probably differ.

[Burnt Fingers]

Way to low temp, even 350 C is only 650 F and barely liquid. That alloy needs to be 730 F or so. Something big wrong with temp measurement?

350F isn't the same as 350 C. Not even close.

OP:

Did you clean the mold before the heat cycles?

How heavily did you smoke the cavities? They should have just a slight bit of color to them. Not totally black.

[Bazoo]

The art of bullet casting book has a section on defects and causes.

I clean my moulds with lighter fluid. With the mould hot and the blocks closed but sprue cutter open, I fill the cavities with lighter fluid. It boils, removing any oil contamination and leaves a thin carbon layer (I suspect). It doesn't cool a warm mould like brake cleaner would.

Defects acceptable to me include a small pulled sprue cut, a slight wrinkle or crease on a driving band, a very small inclusion in the lube groove, surface spider webbing or graying from needing fluxed (this I describe as visual imperfection and will largely disappear if you rub with a towel).

What I discard for is any roundedness of the driving bands. Any large inclusions, or any inclusions on the driving band. Wrinkles. Very large hole at sprue cut. And I reject any with a hole.

I'm more picky about rifle bullets than pistol bullets. I continue to be a better caster than I was previously so I'm always upping my level of desired perfection.

[oley55]

Is there a thread with examples of different casting defects, and how to resolve them? Maybe some guidance on what imperfections are acceptable for plinking?

My first session today gave me 95% reject rate due to rough surfaces, with a few wrinkles too. I might be too picky on the rough surfaces.

I guess there isn't a thread which identifies typical defects and causes other than tin content, temps and mold contaminants. Mores the pity as I was hoping there was one. I'd like to know more about sprue cutter issues; tear-outs, smears and etc...

[robg]

wrinkles =low temp or oil etc in mold .clean mold higher temperature or add more tin.

[GregLaROCHE]

Seems the first issue to address is the temperature. There seems to be a bit of confusion. Does the OP know what temperature he was casting at? A simple way if you don’t have a thermometer or you aren’t sure if it is correct, is to keep heating the alloy until the boolits begin to have a frosty look and then turn down the heat some. Frosted boolits are fine to shoot too.

[justindad]

Did you clean the mold before the heat cycles?

How heavily did you smoke the cavities? They should have just a slight bit of color to them. Not totally black.

I cleaned the molds with dish soap and a toothbrush before smoking. The flats between the cavities had a black coating, but the actual cavities did not have any visible deposits.