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View Full Version : Pounds per inch in Lee 20 pound pot?



JimA
05-17-2014, 05:21 PM
Has anyone ever calculated how many pounds of melt there is in a Lee 20 pound pot by the space left to the brim?
I realize this would be approximate depending on alloy. I have a good deal of pure/soft lead that I would like to add tin to in the pot. It would be easy to weigh the tin to make the desired alloy if I knew how much lead was in the pot.

lancem
05-17-2014, 06:30 PM
Since all mixes are ratios I would think that finding the volume of the pot empty then calculating the volume of the space left to the brim necessary for your ratio would be the way to go.
volume=Pi * r squared * h
where:
π is Pi, approximately 3.142
r is the radius of the circular end of the cylinder
h height of the cylinder

So say you want to add 2% tin, and now you know the total volume transpose the formula for h and use 2% of your calculated total volume and solve for the height needed. Once you have that just fill your pot with pure lead to your 98% volume and top it off with tin.

zuke
05-17-2014, 07:12 PM
:goodpost:

JimA
05-18-2014, 09:04 AM
Thanks. I'll try that.

Mike W1
05-20-2014, 10:06 PM
I did compute my Lee 10 pound pot at I believe 9.96 pounds to the bottom of the "lip" that goes over the top. Made a little dip stick out of aluminum with I believe 3/8" spacing so I could tell how much was left in the pot. Just more working of a very idle mind but it works!

vidiot
05-20-2014, 10:10 PM
I loves intelligence :2_high5:

mdi
05-21-2014, 11:29 AM
what alloy? You do know that different alloys used for bullet casting weight differently per volume...

gwpercle
05-21-2014, 04:01 PM
Pie are not square....Pie are round....Cobbler are square.
Easy answer is 20 pounds , Mr Lee said so. No math required....sometimes you got to have the faith and believe.

Springfield
05-21-2014, 04:37 PM
They hold about 17 lbs unless you like the level even with the top. No real way to safely get 20 lbs in there.

JimA
05-22-2014, 01:21 PM
I have calculated they will hold 19.96 pounds filled to the brim, or 5.15 pounds per inch with pure lead. That's close enough to figure my added tin/pewter percentage.

ohland
06-04-2014, 06:52 PM
I have calculated they will hold 19.96 pounds filled to the brim, or 5.15 pounds per inch with pure lead. That's close enough to figure my added tin/pewter percentage.

OK, it appears we got us a scientist here! For me, math without alcohol HURTS!

What is the head pressure in PSI per quarter inch upwards from the bottom of the pot?

Super trivia round, what is the velocity of the alloy coming out of the spout at each quarter inch rise in height?

Alpha geek skinny chest thumping, pocket protector adjusting bragging rights, what is the volume of alloy coming out from the spout for each second the spout is open for each quarter inch rise in alloy height?

To me, the pot capacity in pounds of lead (or adjusted to whatever alloy) is just data.

:2 drunk buddies:

dragon813gt
06-04-2014, 07:21 PM
Why do any complex complications? Put a known quantity of lead in the pot. Measure how far it came up in the pot. Then do simple division to find out how many pounds per inch. I don't put more than 16#s in for safety reasons.

JimA
06-05-2014, 01:12 PM
[QUOTE=ohland;2808230]OK, it appears we got us a scientist here! For me, math without alcohol HURTS!QUOTE]

Alcohol was definitely involved in the calculations...:-P

I found a site that had done all the math for me.... http://www.custompartnet.com/quick-tool/weight-calculator
Close enough for my use.

I have a good source of pure/soft lead that I needed to add tin to and I didn't want to drain the pot. It is simple to measure from the top down to calculate the pounds of lead in the pot if you know the pounds per inch. I then go to our friendly lead alloy calculator and find the amount of tin needed. I pour ingots until I get near the bottom and fill it back up with my soft lead and start over.

Djones
06-08-2014, 06:51 AM
Does the bottom of the pot have a radius or is it a true cylinder? If it has a radius on the bottom the formula to calculate volume of a cylinder is not valid.

Airman Basic
06-08-2014, 09:48 AM
We're kinda slow down here, but I would weigh the empty pot, then fill it to my preferred level with my preferred alloy and weigh it again. Then do some of that arithmaticin'.

mold maker
06-08-2014, 09:55 AM
An old set of bathroom scales solves lots of problems.

Djones
06-08-2014, 12:42 PM
We're kinda slow down here, but I would weigh the empty pot, then fill it to my preferred level with my preferred alloy and weigh it again. Then do some of that arithmaticin'.

Your said method is Too easy and too accurate.
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