Need hardest lead alloy for casting round ball for ball mill.

[passgas55]

I plan on building a ball mill for making blackpowder. I am going to cast round ball and want the hardest lead balls
I can make. At one point I was thinking of using about 10% zinc but do not know if using zinc in my lead could be a spark hazard. I do have wheel weights. Which direction would you go in?

[Toymaker]

A touch of silver already alloyed with lead or tin would give a very hard alloy.
You could order some Laser Cast bullets and melt them to cast roundball. That's about BHN 35.
You could grind some copper sulfate crystals and mix it into your wheel weight alloy it there's some zinc in it. Stir until the crystal powder turns white then add some more and repeat. The copper replaces the zinc.

[passgas55]

Toymaker , thanks for the info. This will help me out in making a very hard lead ball.From some more of my readings I think it is safe to use zinc in the ball mill. I don't mind the zinc being there. I will add a little zinc then the copper sulfate method to get a hard alloy. If all else fails I just add more zinc at the end.

[Half Dog]

Do you have the setup to heat treat?

[jmort]

I would get a balanced lead alloy 94/3/3 or Lyman #2 90/5/5
And heat treat it
It will get real hard
My opinion, is to avoid Zinc, but if that is the direction you want to go, then go for it.

[popper]

beryllium copper is a non sparking alloy but any dust from it is very toxic. Monel metal ball bearings should work. I would assume a conductive rubber tumbler?

[Soundguy]

I would think something like foundry type ( 64.5 lead, 23 antimony, 12.5 tin ) or something like rotometals super hard.. 70/30 lead/antimony.

[Whiterabbit]

Passgas, don't overthink this.

Hardball is good enough. 92/6/2 is fine. If you want to go harder, use mono or lino type metal and be done. Concentrate more on what you are milling.

The real key is round balls, about 50 cal, and about half full on the drum. It's a simple formula.

No need to heat treat, take care of the sprue, etc etc etc. Roundball is key (no conical bullets), and about 50 cal size is good. I'm using 58's. The balls will self polish into perfect milling media.

[John Boy]

Why not just spend the few bucks and buy some stainless steal chrome loose bearing balls ... https://bearingballstore.com/

[Whiterabbit]

Sparks. Even if unlikely.

We use lead.

[popper]

passgass - I've gone to 2% Cu which dents superhard when WD. You could completely convert #2, don't know what temp to cast - 5% is about the highest you can go. 2% casts fine @ 730F. Superhard doesn't cast very well - too hot and the surface gets lots of pits. You going to use a wet method? Just don't add Al. powder to it - did that as a stupid kid.

[rwadley]

Marbles?

[rockrat]

#2 Babbit would be pretty hard.

[Walstr]

E.G. onlinemetals.com has 25, .5"dia. brass balls for $12. Many other sizes to compose a good mix & sounds safe to me.

[dondiego]

Passgas, don't overthink this.

Hardball is good enough. 92/6/2 is fine. If you want to go harder, use mono or lino type metal and be done. Concentrate more on what you are milling.

The real key is round balls, about 50 cal, and about half full on the drum. It's a simple formula.

No need to heat treat, take care of the sprue, etc etc etc. Roundball is key (no conical bullets), and about 50 cal size is good. I'm using 58's. The balls will self polish into perfect milling media.

Thanks for this info. I was planning to use some linotype conicals. Why is it important?

[country gent]

Use up those zinc wheel weights. melt over a propane burner and use steel mouds youll need to get it up to around 900* - 1000* but will make some very hard balls and use a material you have sitting around probably