Cast Boolit Calculator

[TacAlert]

If pure lead has a BHN of 5 but the bottom value on the calculator shows 8.6 (which from my understanding is more indicative of WW or implies some SN or SB has been added). Maybe I am using the bottom value wrong but nothing matches the BHN value on the right.

I know the calculator has been up for a while. Does anyone have an update?

If not, does anyone know of another way to calculate (other than the tic-tac-toe cross)? I have about 100 lbs of pure lead (BHN 5) that I need to mix for my many projects :)

Thanks

[Delkal]

AFAIK all of the calculators use lead as 8.6 and while this works for most calculations it is off a little for a high dilution alloy like 40:1. If you look at the published data for 40:1 it is ~BHN=8 but if you enter 40 lbs lead and 1 lb tin you get BHN=9.3 with the calculator. The calculation error becomes insignificant and goes away once you get to 20:1 and BHN~9-10.

How soft of an alloy do you want and does it matter if it is BHN 8 or actually 9?

[jdgabbard]

Yeah, the spreadsheet calculator doesn't work for near pure alloys. I like the idea of the calculator, but have given up on using it.

[mehavey]

Again, see https://castboolits.gunloads.com/showthread.php?469290-16-to-1-hardness&p=5732771&viewfull=1#post5732771
For actuals on binary lead-tin alloys.
("Settled Science" does have a hard time dying)

[Forrest r]

Again, see https://castboolits.gunloads.com/showthread.php?469290-16-to-1-hardness&p=5732771&viewfull=1#post5732771
For actuals on binary lead-tin alloys.
("Settled Science" does have a hard time dying)

Again

Lead/tin alloys age soften!!!!

You're testing of lead/tin alloys months after they're made will read "softer" then what they were when made.

A link that explains this
http://www.lasc.us/CastBulletAlloy.htm

Tin (Sn) Tin melts at 449o and alloys very easily with lead. Tin was used for many years as the hardening agent in lead. In the years of large caliber, big bore black powder cartridges the minimal hardening effects of tin was sufficient. With the advent of smokeless powders and much higher pressures and velocities and far sharper pressure/time curves of the faster smokeless powders tin’s limited hardening/strengthening effect on lead left alloys too soft for many cartridges.

Lead/tin alloy’s age soften quickly and the higher the percentage of tin the faster the age softening. If your lead/antimony/tin bullets are to be quenched or heat treated (lead/tin alloy does not respond to heat treatment) the percentage of tin will affect the final amount of hardening that can be achieved, the higher the percentage of tin the lower the final BHN in addition to faster age softening. Lead/tin alloy should age soften at a fairly steady rate for 25 or 30 days and then soften very slowly after that. Be that as it is, tin is still a very valuable addition to the bullet casters alloy. The true value of tin for today’s bullet caster is that it helps reduce dross during casting which enables it to reduce the surface tension of the melt. It does this by inhibiting the oxidation of the metal entering the mould and enabling a more complete fill-out of the moulds intricate details. NOTE: It is not only the surface of the melt in the pot subject to oxidation, the stream of alloy from a bottom pour pot or casting ladle is also in contact with oxygen and this is where tin has it's largest benefit in reducing oxidation and aiding better mold fill-out, from the spigot to inside the mold. Tin does add some hardening/strengthening to lead alloys but at the percentages in most bullet alloys it is minimal. [7]Maximum hardness of lead/tin alloys is 17 BHN at 63% tin and 37% lead (commonly known as 60/40 solder). Tin lowers the melting point of lead alloys, eutectic 60/40 solder melts at 361o F. Loss of tin from the alloy from oxidation is low as long as the melt is not overheated. [8]Tin provides dross protection up to about 750o and also improves castability. Casting temperatures with alloys containing tin should be held to about 700o so that tin’s ability to reduce dross won’t be lost.

While the calculator has it's own issues.

Things like age hardening of alloys with antimony will change the hardness of an lead/antimony/tin alloy.
Things like age softening of alloys with tin will change the hardness of an lead/tin alloy.

[mehavey]

You're testing of lead/tin alloys months after they're made
I'm testing immediately (12-24 hrs) after they are cast.

BUT.... I'll go out and cast some 200gr 10mm 30:1 this morning and test

- Immediately
- 1 day
- 3 day
- 7 day
- 2 week
- 1 month

I'll let you know.

[Rickf1985]

I have been saying this for years and I even tried to remake the calculator on my computer using the true vales for pure lead but I do not have the skills on the computer. 3.5 points on the BHN scale is a big deal if you are thinking you have 5 BHN for pure and they are using 8.6. This is something that Rotometals thought up I believe. All that is needed is to reconfigure the pure lead as a value of 5 but I do not know how to do that. I was a master auto mechanic, not a programmer.

[jdgabbard]

I have been saying this for years and I even tried to remake the calculator on my computer using the true vales for pure lead but I do not have the skills on the computer. 3.5 points on the BHN scale is a big deal if you are thinking you have 5 BHN for pure and they are using 8.6. This is something that Rotometals thought up I believe. All that is needed is to reconfigure the pure lead as a value of 5 but I do not know how to do that. I was a master auto mechanic, not a programmer.

I'll take playing with the formula in each of the result cells. The BHN is hard programmed into them. The only way to truly correct it is to actually write a program to calculate it, instead of a generic excel formula that is prone to inaccuracies.

[mehavey]

I'll just keep a running Track:
These will be individual measurements on individual bullets, so I expect variation.
What we're looking for is trend over time

BHN meas:
30:1 (RotoMetals)
RCBC 10mm 200gr SWC
Microscope: Celestron
Magnification:39.49
Lee Hardness Tester (same as calibrated for 30:1 with ATS/Marietta, GA)

06/18/24
Time after cast (15 min)
Diameter Impression(in): 0.93
BHN: 5.6

06/18/24
Time after cast (2hrs)
Diameter Impression(in): 0.92
BHN: 5.7

06/19/24
Time after cast (24hrs/1 day)
Diameter Impression(in): 0.92
BHN: 5.7

06/25/24
Time after cast (1 week/7 days)
Diameter Impression(in): 0.93
BHN: 5.6

[TacAlert]

Thank you for the reply. But I purchased pure lead (no tin) from Rotometals which has a BHN of 5.
I posted this question because assuming all lead sources are WW 8.6, then it makes it extremely difficult to calculate the proper alloy mix. I purchased some superhard and hopefully, that will help.

[Tom Myers]

This is the Brinell Hardness calculation algorithm that I developed to use in my Precision Casting Alloy Calculator (https://www.tmtpages.com/Alloy/alloycalc.htm)



This formula is constructed from a best fit curve using a rational equation to fit the ratio
of Tin/Lead alloy to a Brinell Hardness chart. It seems to be a very close fit and works well
for me.

Hope this Helps

Let BH = The Brinell Hardness number of the Tin/Lead alloy
Let Tu = Units of tin in the alloy
Let Au = Total units in the alloy
Let T = The ratio of tin to the alloy
Then

T = Tu / Au

BH1 = ( -7.81904 * T * T ) + ( 222.50132 * T )
BH2 = 23.121604 * T +
BH = BH1 / BH2 + 5

1 unit of Tin and 19 units of Lead = a 1/20 Tin:Lead Alloy
1 / 20 = 0.05
BH1 = ( -7.81904 * 0.05 ) + ( 222.50132 * 0.05 ) = 11.1055184
BH2 = ( 23.121604 * 0.05 ) + 1 = 2.1560802
BH = ( 11.1055184 / 2.1560802 ) + 5
Brinell Hardness = 10.15 for a 1/20 Tin:Lead alloy

Measuring the Brinell Hardness Number of an alloy cheaply

1. Pour an ingot of pure lead and an ingot of your sample alloy. The ingots need not be large ( I used to use bottle caps when they were still available)

2. Obtain a steel ball bearing with a diameter of around 3/8" to 1/2" in diameter. (size is not critical but larger impressions are easier to measure)

3. File one side of each ingot flat and smooth.

4. Sandwitch the ball bearing between the smooth surfaces of the two ingots and place the sandwitch in a vice.

5. Tighten the vice untill no more the 25% of the diameter of the ball is impressed into the pure lead sample.

6. Use calipers and a magnifier to carefully measure the diameter of each impression in the ingots.

7. Record the diameter of the pure lead impression and label it as " L ".

8. Record the diameter of the alloy sample and label it as " A ".

9. The formula for determining the Brinell Hardness " BH "of the alloy sample is;

BH = ( L / A ) x ( L / A ) x 5

Let's say that you have some alloy that is supposed to be Lyman # 2 but you are not sure.
Pour and prepare the ingots as described above then hunt around untill you find that old 1/2" ball bearing that you dropped in your "possible drawer" a few years ago.

Sandwitching the bearing between the ingots and squeezing them in your vice untill the impression in the pure lead ingot is just under 0.125" in diameter. (0.5" / 4) and then using a magnifier and calipers to measure the impressions, you find that the impression in the pure lead ingot is 0.121" ( L ) and the impression in the alloy ingot measures 0.070" ( A ).

Now you divide 0.121 by 0.070 with a result of 1.7286.

Next, multiplying 1.7286 x 1.7286, you obtain a value of 2.988.

Multiplying that product by 5, you obtain the estimated BHN. 2.988 x 5 = 14.94

You are still not sure that the alloy is Lyman #2 but you can be fairly certain that the Brinell Hardness number is quite close to #2 Alloy.

(Click on the image to see full size)

327838

[mehavey]

Because of the spherical geometry in calculating the depression surface area, squaring the ratios is doggone close,
but raise that power to 2.21 and you're pretty much right on (assuming pure lead is actually BHN 5) *


*
Use 2.1993 if you believe (and I do) that pure lead actually is BHN 4.5
https://castboolits.gunloads.com/showthread.php?292459-BHN-calculations&p=3441666&viewfull=1#post3441666
:groner: :dung_hits_fan: