Hardness tester

yomomma said:
There is a formula...Lees works off it.
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The LEE tool works off of a formula based on applying a known quantity of force to the indent ball:

BHN = 2 P / (π D (D - (D[SUP]2[/SUP] - d[SUP]2[/SUP])[SUP]1/2[/SUP])) (1)
where
BHN = Brinell Hardness Number
P = load on the indenting tool (kg)
D = diameter of steel ball (mm)
d = measure diameter at the rim of the impression (mm)
​
So if you know the force being applied then you don't need the soft lead comparison Frogge is talking about. That's why I was asking him how he calculated BHN using his method because I don't know of a formula that gives a BHN value from comparing one indent to another indent.
 
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jethunter said:
That will get you an educated guess. It's about half way between a real hardness tester and using a thumb nail.
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That is all you will get with any of the testers affordable by us peons, any sort of comparator method will work close enough for most any home castor. Even for the most anal slug user, consistency in an alloy mix is easily attainable & more important than the actual BN #. If you have a sample of pure lead and one of COWW as well as a specimen of a commercial bullet such as from BB you can come very close to estimating a BN# of your own slugs using any repeatable comparator method.
 
fingers284 said:
That is all you will get with any of the testers affordable by us peons, any sort of comparator method will work close enough for most any home castor. Even for the most anal slug user, consistency in an alloy mix is easily attainable & more important than the actual BN #. If you have a sample of pure lead and one of COWW as well as a specimen of a commercial bullet such as from BB you can come very close to estimating a BN# of your own slugs using any repeatable comparator method.
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That's true but sometimes you get lead and want to get an idea what it is. It's also true better tools only give better results if they are used correctly.

From my experiences:

I notice hardness is influenced by temperature. A cold bullet from an unheated garage in winter takes more force to size than if it warmed up. We should do hardness testing with the alloy the same temperature every time.

Doing a hardness test on cylindrical objects like bullets produce a different shape and size crater/indent than a flat surface. We should use a flat surface for hardness testing.

Lead alloys keep getting harder for a while after casting so we should let the alloy age a few days before testing. This is esp. noticeable with antimonial lead alloy if you heat treat or water drop bullets. Size them right away takes noticeably less force than if you size them a day later.

Tools are only as good as the people using them and the conditions they are used in. The Lee tool is cheap but the results are repeatable. Using 2 brand new Lee hardness testers on the same alloy we've seen differences of 2 BHN in soft lead but they were within 1 BHN on harder alloys. That's close enough for what we use it.
 
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