I am trying to get the most accurate and comparable results from my homemade hardness tester.

Basically, it comsists of an hellical spring,which excerts 50 pounds through an steel ball of 1/8 inch diameter.

The question is: How many seconds do you recommend to maintain the load to get the most accurate measurements?

I will thanks if you indicate how is your test nethod , ball diameter, if it is homemade system, or if it is a Lee, Saeco, LBT, Gussy or another. It would be very usefull for me to know how long these tester manufacturers recommend and if you got better results with a different lead time.

Thanks for your advise

BA Shooter

I have never used a hardness tester for lead, the proper test would be Brinell hardness, look into a machinist handbook for further info on that.

Since I am not the brightest bulb in the circuit, this is the test I would devise for a homemade rig.

I would get these samples:

pure lead

16 to 1 (lead/tin)

wheel weight

Lyman #15

Linotype

I would then conduct a test measuring the indention diameter at 5, 10 , 15, 30, 45, and 60 seconds. To be sure, I would do a few tests at 1 min. 15 sec. and 1 min. 30 sec. to verify that no further growth of the indention occurs. I would then choose a time based on the average time of maximum diameter production.

It would be interesting to see if there is a curve, if the indention depth will grow over a longer time in pure lead than in linotype.

Lee's second edition reloading manual has a discussion of the Brinell test parameters and the design of the Lee tester. Lyman is a good source for a list of alloy hardness. since commercial hard cast pistol alloy and linotype are practically the same hardness, 21 and 22 Brinell, the commercial cast generall containing only 2% tin compared to linotypes 6%, and wheel weight and 16 to 1 being very close to the same at 10 and 11, a tester can only tell us how hard a sample is, not what it is made of. I find knowing what I have more useful than how hard it is, I can figure that out from a chart.

According to Mark's ME handbook, "15 seconds for ferrous materials .... 30 seconds in the case of most nonferrous materials .... longer periods ... on certain soft materials that exhibit creep at room temperature." Lead certainly fits into the latter category. Personally, I use 60 seconds.

I would bring it up to pressure, count 1 and release. If I maintain pressure, particularly on pure lead or soft alloys, the point will keep going in and distort readings.
Doz

On my LBT, I use a slow count to three. Seems to work for me.
I just checked the instructions for my LBT and they say hold for two seconds.
Paul B.

I'm neither a metallurgist nor machinist but do have a bit of background in test & measurement.

My suspicion is that the critical point for repeatability is that the pressure be applied in a consistent manner (force vs. time) & for a consistent duration once you hit peak force. The exact time probably is not near as important as that the time is exactly the same for each test.

Absolute accuracy will depend on both repeatability of the test method and of comparison to calibrated (known) reference standards. Like most things depending on deflection - I suspect that the sensitivity falls off on one end of the scale. In the case of my LBT tester - it is less sensitive at the high end of the scale.

Best regards-

Sky C.

Thanks for your answers.
I see there are several periods of time,ranging from few seconds to 30 seconds , I could add that Lyman Handbook recommends 1 second.
So, there is not a pattern for time. It depends on which works the best for each specific application.
Considering I deal with 9mm and .40S&W lead bullets from 12 HBN to 20 HBN,I will try with 4 or 5 seconds.

Thanks a lot

BA Shooter