Brinell rockwell hardness help

[9453]

Ok new to bullet casting just gathering tooling for now. Now I ran across a rockwell hardness tester. All I seem to hear about is the brinell just not sure why maybe one of you could enlighten me Thanks

[theperfessor]

The basic Brinell test uses a 10mm hardened steel ball and a standarized force to create a hemispherical indentation in the test sample. The diameter of the dimple is measured and used in a formula to determine a BHN, Brinell Hardness Number. This test has been modified to make it work on lead and lead alloys.

The Rockewell test is really a number of tests that use slightly different indentors and loads and are applicable across a broad range of materials and conditions. the Rockwell A is for soft materials, B is for most mild and alloy steel and harder grades of aluminum, C is for hard tool steels and some ceramics, etc. some tests are designed to test thin foils, or just the surface of case hardened materials, and so forth. The depth, not the diameter, is measured and used to determine the Rockwell value.

There are conversion charts that try to compare various Rockwell scales to each other and also to a BHN, but even the charts say that the conversions aren't exact.

I like BHN over Rockwell simply because it covers the complete range of hardness values in a continuum, I don't need to know if it's Rc or Ra.

Why it's used in bullet casting I don't know but I will speculate that it is because it is simple test to do and interpret the results from.

[theperfessor]

By the way, welcome to the forum.

You could use Rockwell if you had the right load and indentor and a way to compare some known materials. Use pure lead as a baseline and then try some other alloys such s 50/50 bar solder, etc. Bet some folks here would be glad to comparison test your samples if you sent them to them.

[9453]

Alright great info thanks, now what brand tester should I be looking for? I'm thinking that I'll need one that will do boolits and ingots both.

[Griz44mag]

I use the LEE hardness tester.
I have no issues doing a single bullet or a 1# ingot.
It is around 50-55 dollars and works very well.

[1bluehorse]

I have a Lee also but when I bought mine on sale several years ago they were under 30 bucks. If I were looking to buy one now (I rarely use one) instead of 55 bucks for the Lee I think I'd spend a bit more. Maybe a Cabine Tree, everyone that I've heard of that has one seems to like them and I think at this time they're 127.00 delivered...you can also do some case work with them also...

[cbrick]

9453, welcome to the forum.

Just getting started a BHN tester isn't really needed. As you gain more experience and work on various loads, calibers with various alloys etc it could be handy but for now it's just not something you really need.

I know a lot of people here test both ingots and bullets made from those ingots but in reality this isn't accurate. What determines the final hardness of a lead alloy it how fast it cools. By mass an ingot is much larger than a bullet and it will cool much slower. Rapid cooling is why water quenching a lead/antimony alloy will harden more than the same bullet cast of the same alloy in the same mold but air cooled.

Rick

[Moonman]

Buy a Cabine Tree.

[Griz44mag]

I kept hearing about the Cabinetree, so last night, I ordered one.