Alloy BHN

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  • Last Post 01 July 2019
shootcast posted this 29 June 2019

Years back I found this on the web. However I cannot find it any longer. This address brings no results but maybe you’ll have better luck. http: www. prfelr0.f2s.com/prfelr0/hardness/hardness2.jpg

If you have a drill press this rig works OK. Also you will need a 7/16 dia. Ball bearing. I made a stem to hold the bearing and secure the stem into the chuck of the drill press. The drill press is never turned on. It is simply a way to easily apply pressure to the sample. Another item of need is your bathroom scale. Adjust the table of the drill press to allow room between the ball bearing which is mounted in the chuck and the bathroom scale which sets on the drill press table. Put your sample alloy on the scale and lower the press handle to apply  200 lbs. of pressure. Dwell about 3 seconds and let off. Measure the indent diameter with your calibers. Cross this measurement to the chart for your BHN . On the low end a diameter of .190 equals about 4.7 BHN and on the high end a reading of.090 equals about 21.7 BHN. I have compared samples to other commercial testers and would say this is accurate. 

Dia.                 BHN 

.090                21.7

.095                19.0

.100                17.9

.105                16.2

.110                14.4

.120                12.1

.130                10.4

.140                9.0

.150               7.8

.160               6.8

.170               6.0

.180               5.3

.190               4.7

My copy is faded but as far as I can tell this is what it reads. Close enough for me. Hope you enjoy.

 

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TRKakaCatWhisperer posted this 29 June 2019

Here's a link with a bit-o-background:  https://en.wikipedia.org/wiki/Brinell_scale

(of course using a 10mm ball and loads in kg.)

 

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John Alexander posted this 29 June 2019

Using a 10mm ball and the right load in kg with this approach is about as close as you can get to the standard Brinell test (assuming your bathroom scale tells the truth) without buying the official apparatus which is very expensive.

The other approaches may be close enough, or not, throughout the range of hardnesses for cast bullet shooters but are all non-standard tests and may be off for part of the range. This includes the usual commercial devices (LBT, Lee, ect.) Of course some of them (pencil and LBT) have the advantage of being quicker and probably good enough for our purposes.

John

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BudHyett posted this 01 July 2019

The common lead hardness testers (Lee, SAECO, LBT, bathroom scale-Brinell) will be accurate for our usage. The question is the degree that each is repeatable. I have found these to be repeatable enough for my usage, but there is a bit of an art included. The bullet caster needs a repeatable tool and needs to use it the same each time. There is a little bit of art in the usage, doing the steps in the same manner. 

And the hardness varies with the time, most alloys need several days to "set up" and be hard. Casting and sizing two nights before a match, then loading the night before the match did not produce the scores as well as winter casting and sizing, then loading two nights before a match. 

Farm boy from Western Illinois, living in the Magical Pacific Northwest

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shootcast posted this 01 July 2019

Yes the hardness changes as time goes by. I usually blend w/wts. With Lino and now even hardball. Just remember the total amounts of each and the results stay pretty much the same. Quenching from the mold this will harden in about three days pretty much as far as it’s going to. This from my testing up to about a year. Can’t tell much past that because I don’t keep them that long. This gives a BHN back near Lino . Is this the best technique? Probably not judging from my scores. Oh well, I’m out shooting having a great day with others that enjoy shooting also.  

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