Making my own hardness tester

[Shotgun Luckey]

I am helping a newly widowed relative clean out her basement and have hauled out over 300 lbs of lead ingots. My only problen is, they weren't labled and had gotten mixed and re-mixed so I can't even be sure one bucket is all the same alloy.

So I figured I needed a lead hardness tester. Now, I'm not a machinist or engineer, but I'm working on building may own tester. I've done some prototyping and believe I almost have it figured out. Now I'm waiting on a magnifier with a scale to more accuratly measure my indentions.

I don't think it will be precise enough to cross directly to a BHN but it will give me a relative scale of hardness. I've tested it on pure lead, wheel weight, 20-1 alloy, pure tin, and lino type and have been able to accurately rank them in terms of hardness.

Has anyone else done this with success?

[Buckshot]

..............To use an imprint type hardness tester you have to have pure lead for a baseline. Everything is determined from that. Otherwise the tester itself can be very simple, but it needs to be consistant in operation. Also, your sample should have a smooth surface to recieve the imprint. It should also be thick enough so the imprint isn't affected by the supporting surface.

The Lyman Cast Bullet Manual has a formula used to convert a sample imprint OD to a BHN number. This is based also on using the pure lead OD in part of the formula so if your pure lead sample isn't really pure, your continueing results will be skewed because of it.

...............Buckshot

[Stove_Pipe]

Maybe something like a automatic Center punch could do a consistant imprint?

[Piet]

http://en.wikipedia.org/wiki/Brinell_hardness_test
You will find the Brinell hardness formula there. The Lee hardness tester uses this calculation.
You need the Applied vertical load, the diameter of the indenter ( steel ball from a ball bearing)
and the size of the indentation in the lead alloy. The easiest way is to make a spreadsheet.