Lead hardness tester

[dbldblu]

On the mini lathe thread I was asked for details of a lead hardness tester I made. The idea comes from the Lyman third edition cast bullet manual, page 115. You use your reloading press to indent a cast bullet with a ball bearing and a fixed load. The diameter of the indent is related to the hardness of the lead alloy by an equation that they list.
Hardness = 5 (Diam of indent in lead/Diam of indent in sample)2

They used a spring loaded gizmo as the load. As long as the spring is compressed to the same amount each time then the load is the same. I decided to go a simpler route and just use a fixed weight (barbell plates). There are three components to my hardness tester as shown in picture 1. On the left is a platform that snaps in like a shellholder on my press. In the middle is the body of an old die. On the right is a barbell plate support part that slides into the die.

[dbldblu]

Picture 2 shows the barbell plate support inserted into the die.

[dbldblu]

Picture 3 shows the parts on a press. There is a cast bullet on the platform and a ball bearing is sitting on the bullet. The ball bearing is .250" diameter. A dab of grease will keep it there. For the picture, I used a 5 lb barbell plate, but, in reality I use 100 lbs of plates for actual testing. The amount of weight is not critical as long as it is the same each time you use it. To use it you lower the operating arm of the press until contact. Then a little farther to just lift the plates. The press has lots of leverage and it is easy to lift the 100 lbs. You make an indent in a pure lead bullet and measure it with a magnifying glass and caliper. That is your standard and then you can make indents in samples and measure them. Plug the measurements into the equation. With 100 lbs of plates and pure lead I got a .136" indent. With wheelweight alloy I got a .095" indent. The equation says my wheelweight alloy is 10.2 BHN. I use the same bullet design for all measurements. It is the Lee 252 grain bullet intended for 45 Colt. The bullet needs a flat nose significantly larger than the ball bearing.

[cheese1566]

Nice!

[RobS]

Like this:

http://i612.photobucket.com/albums/tt206/RobS01/4.jpg

http://i612.photobucket.com/albums/tt206/RobS01/6.jpg

I made this one two or so years ago.

[akraven]

Looks like a great project for the lathe. Thank you for taking to the time to post it!!!

[Charlie Sometimes]

Great idea, and simple to make. :smile:
I had a similar idea, but no way to make it.
I was going to try and put a 30 lb. spring loaded shaft in a die using a similar set up.
The die would be adjusted to test hardness at the top of the ram stroke and read BHN on a scale rod on top of the press.
Got some of it figured out, but no way to apply it.