How accurate can my bhn testing be

[OnHoPr]

I have a early 70's 700 VersaMec. I take the wad finger assembly off. I then insert a 1/2" bolt into the drop tube so that the hex head is only showing and temporarily duck tape it there. I then adjust my wad tube down to the approximate level. I put an ingot on the shell base plate. Next, I take my ice fishing gillin hemos and place a 5/32" ball on the ingot. I bring down the wad tube with the hex bolt in it on to the ball with 60 lb. of force from 30 second test to 60 second test. I then take off my BIFOCALS and with good light try to measure with Lyman 6" dials and reference accordingly to the chart in Lee's book. The ww's that I have tested this summer after cooling down or shall I say the same day have been in the low 9's BNH. If this is semi-accurate, could there be any possible curves for testing BHN this way with other alloys or heat treating which may lead me to inaccuracies in initial load development. Thanx :castmine:

[kylix.rd]

I use the online calculator here: http://www.ajdesigner.com/phphardness/brinell_hardness_number.php

In your case the load weight is 60lb and the indentor is .15625 inch. Get the diameter of the indentation and enter the values with the proper units into the fields one the above page.

Based on getting around the low 9s for your bhn, the measured diameter should be around .073-.075 inch.

[bumpo628]

That is a nice website you found there.

[cajun shooter]

It is not that important to be dead on with your alloy BHN. It's only a reference number that will help you make more alloy or decide what to do with the stuff you have on hand.
The biggest use I have for my Cabin Tree gauge is that time when I purchase lead or find lead and it is of a unknown BHN.
If you shoot SASS as I do and your castings are from 10 to 13 BHN, you are fine. It does not have to be an exact science.
The barrel fit to your gun is your most important factor as that will determine your accuracy, leading or not and easy or hard clean up. A ballpark BHN that fits the bore and will have obturation is what you need to have a easy casting life.

[40Super]

The main use I have for a tester is too get a rough reading so I can keep several batches the same hardness. Accuracy isn't as much of a concern to me as long as I use the same tester/process every time. As stated already fit is #1, then true hardness is almost nothing.

For calibration I use some pure lead boolits, then I know roughly where 5-6bhn is. I also have some pure lino so I know where 28-30bhn is.

[runfiverun]

get a couple of known samples some pure some linotype etc and make your dents.
now do a chart.
you just calibrated your machine.

the way you do it is the way they used to do it at home back in the day.
you'll never know the exact make up of what you are testing but you will know pretty closly how hard it is.