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Rusty Shackleford
07-17-2008, 08:47 PM
I have some 1lb. ingots, I think they are linotype. I don't own a hardness tester. Is the sound an ingot makes when it is dropped on concrete a reliable way to test what it is or hardness? They have a higher pitched tone than a WW ingot when dropped.

John Boy
07-17-2008, 09:31 PM
Lead Hardness Test
Here is a simple way to test the Bhn number of unknown lead samples: all you need is a caliper, two bottle caps, a vise, a 5mm diameter (aprox. size) ball bearing, and a known pure sample of lead

1. Melt enough lead to fill one bottle cap with unknown sample, and the other with known pure lead. Make sure the surface is smooth and flat when the lead hardens and cools.

2. When the lead is cold, put the ball bearing between the two lead surfaces and squeeze this "sandwich" in the vise until the ball is driven partly into both surfaces (just enough to make a fair sized dent, but not past the middle of the ball).

3. Remove the sandwich and measure the two dent diameters. First measure the known pure lead dent and write down this number. Then measure the dent diameter in the unknown lead sample and write it down. Square both numbers (multiply times themselves). Then divide the resulting square of the unknown lead dent diameter into the square of the known pure lead dent diameter. This could be written as (L times L) divided by (X times X) where L is the pure Lead dent diameter, and X is the unknown lead dent diameter.

4. The answer should be a number of 1 or greater. If it is a fraction, or less than 1 in value, you have inverted the two dents and divided the wrong way. In that case, try again. When you get an answer that is 1 or greater, multiply it by 5. This is the actual Brinnell Hardness Number of the unknown sample.

The reason that you will always get a number of 1 or greater is that the ball will always go further into soft material (pure lead) than it will into hard material (any alloy of lead with tin, bismuth, antimony, etc.). Therefore, the diameter of the dent will always be smaller in the unknown sample, if it is harder than pure lead, or the same as the known pure sample, if it is also pure lead. When you divide a smaller number into a larger one, you always get something greater than one for an answer. Brinnell numbers are all greater than one. You must multiply the answer by 5 because this is the adjusting constant for pure lead, which is Bhn 5 hardness.
This method is as accurate as your sample purity and your ability to read the diameter of the dent. A smooth surface is necessary so you can get a clean diameter to measure. A rough surface will throw off the answer because you may not get a true diameter to measure, if one side of the lead surface is higher or wavy.

But in general, this is as accurate a method as any that uses tools which cost less than $500. A reading with an accuracy of only Bhn plus or minus 0.5 will be more than sufficient for purposes of swaging. When the Bhn number actually increases from 5 to 10, or doubles, the pressure goes up by a factor of four, or the square of the increase in hardness.

Rusty Shackleford
07-17-2008, 10:07 PM
John Boy,
That is pretty cool, i'll save that post and try it sometime.
Thanks Rusty

jhalcott
07-18-2008, 07:50 PM
That will definetely tell you the hardness, but wont tell much about what MAKES it hard. I call this stuff "MYSTERY METAL". I melt a batch and see how hot it has to be to become liquid. Then I add some WW or pure lead and test a sample for hardness. If I guessed right on the original melt/mix I start to make bullets. OR I go sit in the corner and sulk!

Rusty Shackleford
07-19-2008, 09:14 AM
I see alot of you guys here cut your WW's with 50% lead, and that is what I will do. I know these mystery ingots are at least Lyman #2. I only cast for hangun, with speeds under 1200fps. in plain base. I have a fair amount of pipe and roof flanges, and 50/50 bar solder.