I know a lot of the CBA members are also members of castboolits, but I'll come back and post a link when the results are all in and his report is prepared. It should be quite interesting. So far all I've done is look at the 10 bullets and did a “thumbnail” test. I'm already guessing the ones I got are over 16 BHN.
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i believe this to be a blind test also with one or two control bullets, to see the boundaries of sensitivity to these testers.
i would bet that one manufacturer will see a lot of business after this test.
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The preliminary results have been posted here:
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Thanks for the heads-up.
Some curiosities in the data, though: all the per-Bullet observations seem to increase across the rows. Bad ju-ju.
Some real stink? Check out the reported “Raw Data” (which is labelled BHN ib at least one spot) and “Actual Readings Before Conversion” for Lab Tested Hardness: the “Before Conversion” values increase across the row indicating decreasing strength -- but the hardness numbers increase across the row! That ain't right...
I have no idea what to make of a “+ .5” or “+ .1” report when using a SAECO tester -- it seems that the operators didn't understand verniers.
I don't know how the Cabine Tree tester works and have no idea what “Actual Readings” are being reported.
The standard deviations should not be compared: they're derived from values drawn from different domains and (some of) the reported conclusions are not consistent with that statistic's proper use.
I applaud the intent and appreciate the effort -- but think the study methods need improvement. It's still useful, though: the numbers hold some surprises and provide contrast for other similar studies -- like Joe Brennan's.
Stuff like this is very hard to get right...
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The test sample could have been chosen a little more carefully. The cabineTree test readings can be verified by testing known samples of Lead, Lyman #2, and pure linotype. The test samples appear to be testing off the designed scale of the saeco and cabintree units. Perhaps using a blend that is within the designed use range would have been more appropriate and meaningful and left “interpolation” out of the test. I do not have or use the Lee hardness tester. Does it actually read to 40 BHN which I believe some tests indicated? Duane Mellenbruch Topeka, KS
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Interesting data but does it really matter?
I used my hardness as a facility to draw a line in the sand. That ACTUAL BHN is real of little consquence to me. What is more important is how consistent my batches are. The hardness tester number is purely nominal for me which, in real terms, is much like loading data and all other variables in shooting. All the numbers a “nominal".
Cheers from New Zealand
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JimmyDee; I believe that increase you mentioned (bad juju) was simply the order they were printed out from the test results we sent in, rather than the hardness readings in the order they were arrived at. I was tester #14 with a Lee and didn't get increased readings as the test ran on. They were simply entered in increasing order on the results tabulation. Hope this clears that up. Bill
Duane; I think you meant LBT rather than Lee in your post? I didn't see any readings above 29 in the Lee results, and its scale chart only goes to 36.
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Yes, you are correct. There is a lot of information there, and I think I failed to check my notes often enough. I was disappointed that the test samples were at the high end of the scale rather than a more common mid range hardness. But, knowing the amount of samples that had to be produced, and consistantly, it was probably the only way to accomplish the task. Unless a lead/tin mix would have been used. But the expense would have been significant.
I have and use the cabintree tester and it is very repeatable. I also know that it uses a seperate chart to convert the dial indicator readings into BHN readings. There is a chance for error in using this tool, and I have tried to limit that error by adding a plastic tie on the indenting shaft under the brass pointer. It was difficult for me to keep track of my starting point with the markings on the far end of the shaft, and I felt I might make my own error in operation.
Recently, it was suggested that a plastic sheet be placed over the dial indicator to make a direct reading BHN scale. I rather like that idea. I have also used known pure alloy samples to determine that there is some error in the readings I obtain. While it could be corrected mechanically, I will leave it along and just subtract the correction from each reading.
I tend to agree that the actual numbers are not really important as long as one can recreate the same hardness in the alloy for consistant bullets. And it is very helpful in determining just how newly acquired metal compares with your current supply. Duane Mellenbruch Topeka, KS
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Like Jeff said i use mine to compare batches and not to get an exact bhn reading on lead. None of them will do it with precission. I dont care much about the test either. Ive owned an lbt and a seaco and a cabintree all at the same time and sold the lbt and seaco because the cabintree unit is a much better unit and is much more user friendly.
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Bill* said, “...that increase you mentioned was simply the order they were printed out from the test results we sent in."
Yeah, I guessed that. The problem is that there is no way to correlate the raw data with the interpreted data -- which greatly diminishes their value.
Don't get me wrong: it's a worthwhile study with distinctive features and I thank everyone for the effort they contributed. But it could be made better...
(As an aside: you might think that the temperatures at which ice melts and water freezes are well established -- but the NIST is, to this day, publishing the results of contemporary experiments trying to determine what those temperatures are. Obviously, we're not going to get the strength of these alloys nailed down any time soon...)
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Duane, Many thanks for the SACO to BHN chart. Now I can stamp the BHN on my 40 year old ingots as I recast and clean them.
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