Does this formula work?

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  • Last Post 12 January 2015
shootzem6.5 posted this 12 January 2015

Recently i read this formula and am wondering if it`s accurate to any degree. 5 times (lead diameter times test diameter) divided by 2 =BHN. Used with a Ball Bearing and a vise.

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vmwilson posted this 12 January 2015

If I did your formula the way it's written, it doesn't work.  Try this one.

From an old American Rifleman reference the example given was a diameter of .175” in pure lead and .105 in the sample.  Lead assumed to be 5 BHN

BHN = 5 (.175² / .105²)

Thus BHN = 5 (.030625 / .011025)

.030626 / .011025 = 2.7777777

BHN = 5 * 2.7777777

BHN = 13.888888

You have to square the figures to do the calculations. 

BTW for those interested you can insert that little ² in to your text by holding the ALT key and pressing 253.  It has to be done on the keypad not the ones above your letters so I guess laptops won't work.  Couple other useful ones are ALT 0176   ° ALT 0177   ± ALT 0162   ¢

Mike

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shootzem6.5 posted this 12 January 2015

Thanks VM, I didnt know that i had to square the diameters.

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