Calculator for BHN?

[Mike W1]

Is there a calculator that'll determine BHN if you input the percentages of Sn, Sb and Pb?

Have tried several of them and haven't found one that does that particular chore?

[bangerjim]

Do a search on here in the little white box in the upper right corner for "alloy calculator.

It will do everything you need.

Jim

[Ken in Iowa]

Here's a good thread on it.

http://castboolits.gunloads.com/showthread.php?105952-Lead-alloy-calculators

[PBaholic]

Is there a calculator that'll determine BHN if you input the percentages of Sn, Sb and Pb?

Here is the calculator:

BHN = 8.6 + ( 0.29 x Sn%) + ( 0.92 x Sb% )

So for 95% lead, 5% Sn, 5% Sb alloy = 8.6 + (0.29 x 5) + (0.92 x 5) = 8.6 + 1.45 + 4.6 = 14.65

The Alloy Calculator has a few problems. It is starting with an initial value for lead at 8.6, so it is not reliable with high percentages of lead. If the BHN out of the calculator is under 10, it is most likely incorrect. It also has a problem when the Sn goes above 10%.

[Mike W1]

Here is the calculator:

BHN = 8.6 + ( 0.29 x Sn%) + ( 0.92 x Sb% )

So for 95% lead, 5% Sn, 5% Sb alloy = 8.6 + (0.29 x 5) + (0.92 x 5) = 8.6 + 1.45 + 4.6 = 14.65

The Alloy Calculator has a few problems. It is starting with an initial value for lead at 8.6, so it is not reliable with high percentages of lead. If the BHN out of the calculator is under 10, it is most likely incorrect. It also has a problem when the Sn goes above 10%.

That would be Rotometals calculator I believe. Never have figured out how they came up with that 8.6 figure for lead but hopefully they're a lot smarter than I. Ran 8 tests on 4 bullets from a batch I'd made up and consistently got 14 BHN with my LBT tester and aged 3 weeks. Calculator showed 11.8 and 12.3 depending on whether I used the figures on what I added to the mix or Xrf figures from the mix. Close enough I guess either way. Was 95% + lead with either set of figures so I'd say your high lead observation is correct far as accuracy of prediction.

[OS OK]

I've thought about that discrepancy in Pb BHN...thought too that we prolly don't see much pure Pb since our Pb mines are shut down.
So...where do they get the Pb @ 8.6? I think it's all reclaimed, re-smelted in some way that removes as many of the other metals and thats what they call pure Pb.
I have been able to mix batches that come out +1 to +1.5 and using all the various forms of scrap but sweeten with known Pb from RotoMetals like Hardball or Linotype.
I depend heavily on the BHN tester with testing done as accurately as I can manage but we just can't account for the other metals in the mix we are not aware of. If we had opportunity to XRF all the time I suppose we could be more accurate but...close enough, like horseshoes and hand-grenades seems to getterdone well enough...I have clean bores and that's the objective right, well...that + accuracy.

[BAGTIC]

Lead does not come from the ground in pure form any more than gasoline comes out at 89 octane. Pure lead is a manufactured product everywhere in the world. Where do you think the rest of the world gets its 'pure lead' for batteries and chemical purposes.

[bangerjim]

The Pb factor is also a "fudge" factor to make the calculators work. Do we really care what the hardness of pure lead is in a calculator? I sure have never used it to calculate pure?!?!?!?!?

I care more about the 9-22 range....and it seems to be darned close, as compared to my Cabine tester.

banger

[OS OK]

Lead does not come from the ground in pure form any more than gasoline comes out at 89 octane. Pure lead is a manufactured product everywhere in the world. Where do you think the rest of the world gets its 'pure lead' for batteries and chemical purposes.

What an absurd and obtuse reply...maybe you should review for yourself the story of lead. It comes out of the ground as an ore.

A Story Of Lead (1948) (https://www.youtube.com/watch?v=6HhdkkdsvTM)

[PBaholic]

That would be Rotometals calculator I believe. I'd say your high lead observation is correct far as accuracy of prediction.

Yes, that is Rotometals formula. The reason why it is not exact is that to outcome of alloys is not linear, meaning if you were to graph it, you would not get a straight line. The formula is of a straight line. It closely approximates the BHN over a portion of the curve.

Also, there are many issues with measuring the BHN of a specific alloy accurately. Read the article at:

http://www.lasc.us/Shay-BHN-Tester-Experiment.htm

And you will see that BHN measurements were all over the map.

Be happy if your calculation and measurement are within 2:bigsmyl2:

[Ken in Iowa]

Yes, that is Rotometals formula. The reason why it is not exact is that to outcome of alloys is not linear, meaning if you were to graph it, you would not get a straight line. The formula is of a straight line. It closely approximates the BHN over a portion of the curve.

Also, there are many issues with measuring the BHN of a specific alloy accurately. Read the article at:

http://www.lasc.us/Shay-BHN-Tester-Experiment.htm

And you will see that BHN measurements were all over the map.

Be happy if your calculation and measurement are within 2:bigsmyl2:

I totally agree.

Aging and and the Sn to Sb ratio has to play a role as well.