Simple hardness calculator

[Traffer]

This is the simplest hardness calculator I have seen:

https://youtu.be/7Y0raK6_Vbk

[kevin c]

I believe Wiederlader's mixing cross assumes a linear relationship between alloy content and hardness (twice the content of ingredient metal X gives twice the hardness). From my admittedly primitive understanding of metallurgy, that's a rule of thumb that doesn't always hold up closely, but sometimes being in the ballpark is good to go.

[Traffer]

I believe Wiederlader's mixing cross assumes a linear relationship between alloy content and hardness (twice the content of ingredient metal X gives twice the hardness). From my admittedly primitive understanding of metallurgy, that's a rule of thumb that doesn't always hold up closely, but sometimes being in the ballpark is good to go.

I knew that was going to come up. How about "let us assume an alloy of Lead and Antimony." .001% copper or .0001% silver or .000001% zinc all have minor effects of the alloy but for 99% of reloaders this RULE OF THUMB works just fine.

[GregLaROCHE]

That’s pretty cool.

[kevin c]

I knew that was going to come up. How about "let us assume an alloy of Lead and Antimony." .001% copper or .0001% silver or .000001% zinc all have minor effects of the alloy but for 99% of reloaders this RULE OF THUMB works just fine.

Be chill, my friend. I didn't say it wouldn't work. My comment was more to let folks know that they shouldn't worry that there is something wrong if they hardness test the result and it's not exactly as predicted.

And I don't remember any concerns about the other low level metals when this was posted before:

http://castboolits.gunloads.com/showthread.php?402785-Mixing-alloy-for-best-9mm&highlight=Mixing+cross

[Traffer]

Be chill, my friend. I didn't say it wouldn't work. My comment was more to let folks know that they shouldn't worry that there is something wrong if they hardness test the result and it's not exactly as predicted.

And I don't remember any concerns about the other low level metals when this was posted before:

http://castboolits.gunloads.com/showthread.php?402785-Mixing-alloy-for-best-9mm&highlight=Mixing+cross

Yikes, thanks for pointing that out. My dementia is getting bad. (seriously) I sometimes find stuff that I made a few years ago and don't even remember making them. Makes me look like a fool here sometimes.

[kevin c]

It's good to bring techniques to the attention of folks starting out. With a big forum going back years, browsing at random may not turn up useful stuff right away, and even searches won't help if the searcher doesn't know what they're looking for. Can't sticky everything.

[PBaholic]

Yes, as long as you keep your final BHN in the 10 to 16 range this method will work.

I have attached a chart of the 24 to 48 hour BHN hardness of Lead/Tin Alloys. Do you see how flat the line is from 10 to 16?

This is what they call a linear relationship, where you can use simple math (like your video) to calculate the hardness of alloys.

[Traffer]

Yes, as long as you keep your final BHN in the 10 to 16 range this method will work.

I have attached a chart of the 24 to 48 hour BHN hardness of Lead/Tin Alloys. Do you see how flat the line is from 10 to 16?

This is what they call a linear relationship, where you can use simple math (like your video) to calculate the hardness of alloys.

Do you have a graph that has the bhn numbers for antimony and lead? I don't think that there are many folks who use tin to harden lead anymore.
Tin is very expensive.

[PBaholic]

Do you have a graph that has the bhn numbers for antimony and lead?

Antimony (Sb) isn't so simple. The RotoMetals calculator [BHN = 8.60 + (.29*Sn) + (.92*Sb)] is fairly accurate in the BHN 10 to 16 range. So, 96-2-2 (AKA 92:2 SnSb) would be: 8.60 + (2 x 0.29) + (2 x 0.92) = 11.02. I've made this alloy, and measure it at 11.1 after 48 hours.

Alloys made where the Sb and Sn are equal (AKA SnSb) are more stable over the long term. I made a bunch of these alloys to test their hardness. The chart shows my results for 24 hours and 48 hours after pouring. The Calc column is the Rotometals calculation, which appears less accurate at higher and lower BHN's.