# Thread: my math is all kaput

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## my math is all kaput

to think I used to tutor college algebra and have studied trig and calculus...

I'm trying to figure out how to get 1 part tin and 40 parts lead mix using pure lead and solder which is 63% tin and 37% lead...

my mind is all a swim and this stuff used to be so easy... it's very discouraging

My furnace holds 20 pounds of mix… max

2. ## Re: my math is all kaput

This has got to be the most feeble attempt ever at a gun thread.

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## Re: my math is all kaput

Originally Posted by Paul Pless
This has got to be the most feeble attempt ever at a gun thread.
Paul... I serious... I can't even hardly begin... it's the math that troubling me, really... I haven't done this stuff in 30 years

no doubt I could wag it but I want to be able to repeat the mix

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## Re: my math is all kaput

okay... I just started writing knowns on paper... wrote down all I could think of and came up with an answer... will give me 1lb tin in 39 lb lead... close enough so long as it's repeatable

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## Re: my math is all kaput

It does not have to be precise measurement does it?
19 pounds lead + 9 ounces solder.

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## Re: my math is all kaput

now the next problem is weighing the stuff without a proper scale

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## Re: my math is all kaput

Originally Posted by Glen Longino
It does not have to be precise measurement does it?
19 pounds lead + 9 ounces solder.
to get 1 pound of tin I must use 1 1/2 pounds solder... okay I think I have it close enough... the brain cells needed were pretty rusty so what should have been easy was somewhat daunting

getting old

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## Re: my math is all kaput

Originally Posted by TANSTAF1
When you say 1 part do you mean volume or weight? To me a part implies volume not weight. I think lead is much heavier than tin so you can not get the correct quantities by weighing.
it's by weight... but I don't mind approximations so long as it's repeatable

I have bullet/powder scales but nothing to weigh heavier stuff... gonna cast a lot of tin bullets and weigh in enough to get my pound and a half and trust to the manufacturs assertion that the lead pot holds 20 pounds

actually I need to cut my 1 1/2 pounds of solder in half for 20 pounds of lead
Last edited by Phillip Allen; 04-11-2012 at 12:17 PM.

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## Re: my math is all kaput

OK - I get 12.69 oz of solder and 19lb. 3.3oz of lead will give you 20 lbs of mix with a 40:1 ratio of lead to tin.

Is the lead in ingot form? What are the weights of the ingot? Can you use a bathroom scale, compared to something known, like a 5 lb bag of flour, or a gallon of water or something ( to get reasonable accuracy)?

Is the solder on a spool? Unroll the 1 lb spool, measure the length and snip off the correct length, i.e. 12.69/16 = 79.3% of the length.

NB: This gives you an approximate 40:1 ratio by weight of lead to tin ....if you need more accuracy, let me know. Also you won't get 40 atoms of lead to 1 atom of tin with this estimate.
Last edited by JBreeze; 04-11-2012 at 12:32 PM. Reason: NB

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## Re: my math is all kaput

the solder (S) is cast into muffin sized moulds

I will cast a lot of bullets from the solder then weigh in 12 oz of (S) bullets and mark the pot at the full point and add lead until I reach that point... should be close enough I think

11. ## Re: my math is all kaput

Pretty pricey using eutectic solder to make bullets out of. Did you get it surplus?

12. ## Re: my math is all kaput

You have 63 parts tin and 37 parts lead. How many parts of lead do you need to add to have 63 parts tin and (40*63) parts lead?

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13. ## Re: my math is all kaput

Interflux sell "Lead Free anti-oxidant pellets"

They are pure tin.

14. ## Re: my math is all kaput

To make up 20 lbs of alloy at 1 part tin to 40 parts lead by weight using pure lead and solder that's 63% tin and 37% lead, I get 1.3184 lbs of solder and the remainder (18.6816 lbs) pure lead. Here's how I got there. I'm pretty sure my maths are right, but I'm open to criticism:

Code:
```1. Set up your equation:

37         1
---------- = ----
( 63 + X )    40

2. Cross-multiply and simplify:

37 * 40 = 1 * ( 63 + X )

1480    = 63 + X

1417    = X

3. So, for a given weight of solder, you need to add 14.17 times that weight in lead to get to the desired 1 part tin/40 parts lead.

To make a 20 lb batch, then, set up your equation and simplify to get the weight of solder required:

X + ( 14.17 * X ) = 20

15.17 * X = 20

20
X = -----
15.17

X = 1.3184

It follows then that to make your 20 lb batch, you'll need 1.3184 lbs of solder and 18.6816 lbs of lead.```

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## Re: my math is all kaput

Originally Posted by Nicholas Carey
To make up 20 lbs of alloy at 1 part tin to 40 parts lead by weight using pure lead and solder that's 63% tin and 37% lead, I get 1.3184 lbs of solder and the remainder (18.6816 lbs) pure lead. Here's how I got there. I'm pretty sure my maths are right, but I'm open to criticism:

Code:
```1. Set up your equation:

37         1
---------- = ----
( 63 + X )    40

2. Cross-multiply and simplify:

37 * 40 = 1 * ( 63 + X )

1480    = 63 + X

1417    = X

3. So, for a given weight of solder, you need to add 14.17 times that weight in lead to get to the desired 1 part tin/40 parts lead.

To make a 20 lb batch, then, set up your equation and simplify to get the weight of solder required:

X + ( 14.17 * X ) = 20

15.17 * X = 20

20
X = -----
15.17

X = 1.3184

It follows then that to make your 20 lb batch, you'll need 1.3184 lbs of solder and 18.6816 lbs of lead.```
thank you... I haven't set up a problem like that since 1975

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## Re: my math is all kaput

Originally Posted by Phillip Allen
thank you... I haven't set up a problem like that since 1975
Last edited by Glen Longino; 04-11-2012 at 03:41 PM.

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## Re: my math is all kaput

Originally Posted by Nicholas Carey
To make up 20 lbs of alloy at 1 part tin to 40 parts lead by weight using pure lead and solder that's 63% tin and 37% lead, I get 1.3184 lbs of solder and the remainder (18.6816 lbs) pure lead. Here's how I got there. I'm pretty sure my maths are right, but I'm open to criticism:

Code:
```1. Set up your equation:

37         1
---------- = ----
( 63 + X )    40

2. Cross-multiply and simplify:

37 * 40 = 1 * ( 63 + X )

1480    = 63 + X

1417    = X

3. So, for a given weight of solder, you need to add 14.17 times that weight in lead to get to the desired 1 part tin/40 parts lead.

To make a 20 lb batch, then, set up your equation and simplify to get the weight of solder required:

X + ( 14.17 * X ) = 20

15.17 * X = 20

20
X = -----
15.17

X = 1.3184

It follows then that to make your 20 lb batch, you'll need 1.3184 lbs of solder and 18.6816 lbs of lead.```

I think I found a problem:

is the first equation reversed?

it looks like it's set up to show lead over tin in the first half then tin over lead in the second half

I don't know how to put the math on the screen

(63+X) 1
___ = ___
37 40
tried but can't make the typing work
Last edited by Phillip Allen; 04-11-2012 at 02:06 PM.

18. ## Re: my math is all kaput

Please excuse a slight thread divergence, but I've often wondered why math is sometime singular and sometimes plural. Phillip says, "...my math is" and Nicholas says, "...my maths are". Seems like I usually see Americans using singular and others using plural. Is there a better reason for the difference?

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## Re: my math is all kaput

Nick - I think there is an error there somewhere.....1.3 lbs of solder that is 63% tin will give you 13.3 oz Tin. 13.3/320 = ~ 4.2% solution. 1:40 is ~ 2.5%

Long, long time ago, I'd get infrequent calls in the middle of the night asking "I have small amounts of D50W and plenty of D5W. How much D50W do I add to 100ml of D5W to make a D7.5W solution?" After I gave the answer and hung up, I'd scurry to my reference book to dbl. check the math

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## Re: my math is all kaput

well, this is good excercise for me...

I think my brain will be sore tomorrow

21. ## Re: my math is all kaput

Originally Posted by Phillip Allen
to think I used to tutor college algebra and have studied trig and calculus...

I'm trying to figure out how to get 1 part tin and 40 parts lead mix using pure lead and solder which is 63% tin and 37% lead...

my mind is all a swim and this stuff used to be so easy... it's very discouraging

My furnace holds 20 pounds of mix… max

N.B. Lots of he solder now on sale is lead free - and and most of the rest is not the classic 63/37 brew.

22. ## Re: my math is all kaput

Originally Posted by JBreeze
Nick - I think there is an error there somewhere.....1.3 lbs of solder that is 63% tin will give you 13.3 oz Tin. 13.3/320 = ~ 4.2% solution. 1:40 is ~ 2.5%

Long, long time ago, I'd get infrequent calls in the middle of the night asking "I have small amounts of D50W and plenty of D5W. How much D50W do I add to 100ml of D5W to make a D7.5W solution?" After I gave the answer and hung up, I'd scurry to my reference book to dbl. check the math
I think you're right. I hadn't had my cofee yet. I gotta run out the door this minute, but I think I confused my lead and tin.
Code:
```1. Set up your equation:

( 37 + X )     40
---------- = ----
63       1```

Originally Posted by Nicholas Carey
To make up 20 lbs of alloy at 1 part tin to 40 parts lead by weight using pure lead and solder that's 63% tin and 37% lead, I get 1.3184 lbs of solder and the remainder (18.6816 lbs) pure lead. Here's how I got there. I'm pretty sure my maths are right, but I'm open to criticism:

Code:
```1. Set up your equation:

37         1
---------- = ----
( 63 + X )    40

2. Cross-multiply and simplify:

37 * 40 = 1 * ( 63 + X )

1480    = 63 + X

1417    = X

3. So, for a given weight of solder, you need to add 14.17 times that weight in lead to get to the desired 1 part tin/40 parts lead.

To make a 20 lb batch, then, set up your equation and simplify to get the weight of solder required:

X + ( 14.17 * X ) = 20

15.17 * X = 20

20
X = -----
15.17

X = 1.3184

It follows then that to make your 20 lb batch, you'll need 1.3184 lbs of solder and 18.6816 lbs of lead.```

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## Re: my math is all kaput

I look forward to the next episode

24. ## Re: my math is all kaput

For every 100g of solder there is 63g of tin and 37g of lead.

So to every 100g of solder you need to add 2483g of lead, making a total of 2583g, about 5.7 pounds total.

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## Re: my math is all kaput

Originally Posted by htom
For every 100g of solder there is 63g of tin and 37g of lead.

So to every 100g of solder you need to add 2483g of lead, making a total of 2583g, about 5.7 pounds total.
that is the way I finally worked it out

26. ## Re: my math is all kaput

Originally Posted by Phillip Allen
Paul... I serious... I can't even hardly begin... it's the math that troubling me, really... I haven't done this stuff in 30 years

no doubt I could wag it but I want to be able to repeat the mix
find a kid who knows the new math. Knowing what he's doing is more important than getting the right answer, so you can't go wrong, no matter how wrong you go.

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## Re: my math is all kaput

Originally Posted by Phillip Allen
that is the way I finally worked it out

I can use grams, now !?

I was trying to make it easy, with household scales, etc. to get you to 20 lbs.

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## Re: my math is all kaput

Originally Posted by JBreeze
I can use grams, now !?

I was trying to make it easy, with household scales, etc. to get you to 20 lbs.
grams or carats or whatever... conversion is easy... no 'system' is more accurate than another

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## Re: my math is all kaput

Originally Posted by Phillip Allen
grams or carats or whatever... conversion is easy... no 'system' is more accurate than another
Did you end up making 20 lbs total?
How much solder did you end up using?

30. ## Re: my math is all kaput

Hey guys......

..... go metric, eh?

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## Re: my math is all kaput

Originally Posted by JBreeze
Did you end up making 20 lbs total?
How much solder did you end up using?
96 drachms solder to 684 scurples of lead

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## Re: my math is all kaput

Originally Posted by The Bigfella
Hey guys......

..... go metric, eh?
I like barley corns and cubits... you Frenchies are stuck on metric

33. ## Re: my math is all kaput

Originally Posted by Phillip Allen
I look forward to the next episode
Yes...I got a mite confused with the lead and the tin. Here's the updated algebraic solution:

Code:
```1. Set up your equation:

63        1
---------- = ----
( 37 + X )    40

2. Cross-multiply and simplify:

63 * 40 = 1 * ( 37 + X )

2520    = 37 + X

2483    = X

3. So, for a given weight of solder, you need to add 24.83 times that weight in lead to get to the desired 1:40 tin/lead ratio.

To make a batch with a total weight of 20 lbs, then, set up your equation and simplify to get the weight of solder required:

X + ( 24.83 * X ) = 20

25.83 * X = 20

20
X = -----
25.83

X = 0.7743

It follows then that to make your 20 lb batch, you'll need 0.7783 lbs of solder and 19.2217 lbs of lead.```
WRT to units, they don't really apply. In computing the right factor, you're dealing with ratios and percentages, not weights. Weight only comes into play in deciding on your target batch size.

FWIW, to get the fancy dancy fixed-pitch font I used, use the [code]...[/code] markup tags.

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## Re: my math is all kaput

Originally Posted by Nicholas Carey
Yes...I got a mite confused with the lead and the tin. Here's the updated algebraic solution:

Code:
```1. Set up your equation:

63        1
---------- = ----
( 37 + X )    40

2. Cross-multiply and simplify:

63 * 40 = 1 * ( 37 + X )

2520    = 37 + X

2483    = X

3. So, for a given weight of solder, you need to add 24.83 times that weight in lead to get to the desired 1:40 tin/lead ratio.

To make a batch with a total weight of 20 lbs, then, set up your equation and simplify to get the weight of solder required:

X + ( 24.83 * X ) = 20

25.83 * X = 20

20
X = -----
25.83

X = 0.7743

It follows then that to make your 20 lb batch, you'll need 0.7783 lbs of solder and 19.2217 lbs of lead.```
WRT to units, they don't really apply. In computing the right factor, you're dealing with ratios and percentages, not weights. Weight only comes into play in deciding on your target batch size.

FWIW, to get the fancy dancy fixed-pitch font I used, use the [code]...[/code] markup tags.
I ended up using 12 oz solder and because I can't weigh that much lead (I only have a powder scale) I assumed the pot holdes what it's advertised to hold... I measured the finished level at 1/2 inch from the top with a straight edge laid across to measure to

this is repeatable even though It won't be exactly 1/40. The point is to make a very soft bullet but pure lead is hard to cast and the addition of tin is like adding soap to water so it pours better

35. ## Re: my math is all kaput

1) The correct answer is 0.7743 lbs solder to 19.2257 lbs lead. 2) 0.7743 lbs of solder contains 0.63 x 0.7743 = 0.4878 lbs tin and 0.7743-0.4878 = 0.2865 lbs lead. 3) So the total tin is 0.4878 lbs and the lead is 19.2257 + 0.2865 = 19.5122 lbs. 4) 0.4878/19.5122 = 0.0249997. 5) 1/40 = 0.025. 6) QED
Last edited by Todd D; 04-11-2012 at 09:13 PM.

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## Re: my math is all kaput

Originally Posted by Todd D
The correct answer is 0.7743 lbs solder to 19.2257 lbs lead0.7743 lbs of solder contains 0.63 x 0.7743 = 0.4878 lbs tin and 0.7743-0.4878 = 0.2865 lbs leadSo the total tin is 0.4878 lbs and the lead is 19.2257 + 0.2865 = 19.5122 lbs0.4878/19.5122 = 0.02499971/40 = 0.025QED
looks aproximately right to me

37. ## Re: my math is all kaput

Well Phillip. Your math may be kaput, but your problem solving skills are still excellent.

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## Re: my math is all kaput

Originally Posted by ron ll
Please excuse a slight thread divergence, but I've often wondered why math is sometime singular and sometimes plural. Phillip says, "...my math is" and Nicholas says, "...my maths are". Seems like I usually see Americans using singular and others using plural. Is there a better reason for the difference?
"Maths" is correct in British English, and "math" correct in American English. I have no idea why.

39. ## Re: my math is all kaput

Originally Posted by PhaseLockedLoop
"Maths" is correct in British English, and "math" correct in American English. I have no idea why.
Okay Nicholas, you got some 'splainin' to do. Are you a Brit transplanted to Seattle?

40. ## Re: my math is all kaput

Originally Posted by ron ll
Okay Nicholas, you got some 'splainin' to do. Are you a Brit transplanted to Seattle?
No, but I grew up with a bunch of Anglos and Scots and I used to work (here in Seattle) for an English software company out of Cambridge...though the office I worked with was in Alderley Edge, just south of Manchester.

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## Re: my math is all kaput

don't feel bad Nick... I love to play with the language(s)

42. ## Re: my math is all kaput

Originally Posted by PhaseLockedLoop
"Maths" is correct in British English, and "math" correct in American English. I have no idea why.
I think "maths" is plural because there is more than one "math": you've got arithmetic, algebra, geometry, calculus, trignometry, etc. That's why its "mathematics".

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