Will this work?

[kcajeel]

Can I mix 10 pounds of 30 to 1 (mix), to 10 pounds of 10 to 1 (mix), and end up with 20 pounds of 20 to 1?

Thanks

[Whiterabbit]

if one pound is 341 "parts", then 30:1 = 330:11, and 10:1 = 310:31. Add equally and you get 2 pounds, 682 parts, which is 640:42. that is .0656, 20:1 = .05. So actually, you are gonna be a little tin rich still.

.0656 is very very close to 15:1 alloy. You will end up with 20 pounds of 15:1

[NewbieDave007]

^^Agree (basically 14:1)

[johnnysespresso]

Approximately 15.2377:1 Pb to Sn

[ShooterAZ]

This is why we need to pay attention in math class. I sometimes have trouble wrapping my head around alloying stuff.

[NewbieDave007]

9.67 lead + 0.33 tin = 10 lbs of 30:1
9 lead + 1 tin = 10 lbs of 10:1

9.67 lead + 9 lead = 18.67 lead
0.33 tin + 1 tin = 1.33 tin

18.67 lead : 1.33 tin
18.67/1.33 : 1.33/1.33 = 14:1

[jmort]

I never have trouble using weight. So you have .3 pounds of tin and 9.7 pounds of lead and 1 pound of tin and 9 pound of lead and you end up with 18.7 pounds of lead and 1.3 pounds of tin. 20 pounds of 20 to 1 consists of 19 pounds of lead and 1 pound of tin, so close but not 20 to 1.

[badbob454]

heck im a mix it shoot it kind of guy ..... if its hard shoot faster

[sqlbullet]

Mix 1/3 10:1 with 2/3 30:1 to get 20:1.

So, if you want 20 lbs final, mix 6.6 lbs 10:1 with 13.3 lbs 20:1. If you have 1 lb ingots, go for 18 lbs, 6 + 12.

[kcajeel]

Thanks guys with a special thanks to sqlbullet with an explanation that even I understand.

[bumpo628]

As I understand it, the traditional way of mixing lead-tin ratios like 10:1 was to take 10 lbs of lead and 1 lb of tin to make 11 lbs of alloy with 9.09% tin. The other way to do it is to take 9 lbs of lead and 1 lb of tin to make 10 lbs of alloy with 10% tin.

I contacted Rotometals and found out that they use the second method (9 Pb +1 Sn = 10).

Here is a comparison between the two methods for common alloys:
Alloy - Old Sn% vs New Sn%
10:1 - 9.09% vs 10%
16:1 - 5.88% vs 6.25%
20:1 - 4.76% vs 5%
25:1 - 3.85% vs 4%
30:1 - 3.23% vs 3.33%
40:1 - 2.44% vs 2.5%
So there really isn't too big of a difference. The old method saves a bit of money on tin. The new method has nice round % numbers.

Using the old method, I got 15.5 lbs of 30:1 and 5.5 lbs of 10:1 to give you 21 lbs of 20:1.
Notice it is half the amount of a full batch of each alloy.

Using the new method, I got 15 lbs of 30:1 and 5 lbs of 10:1 to give you 20 lbs of 20:1.
Again, it is half the amount of a full batch of each alloy.

Either way it is basically a 3 to 1 ratio.
Wait....is that a new or old 3:1?

Hope this helps.