20# pot?

[Land Owner]

Is the RCBS Pro Melt considered to be a "20#" pot? If it is, I can get no more than 10 weighed pounds of lead ingots in mine to reach its maximum capacity.

Which pots are actually 20# capacity - or are there any? Perhaps the name sticks because the pot, ingots, and supporting structure weigh 20#'s when full?

[Targa]

My Lee 4-20 pot certainly doesn’t hold the 20lbs it says it’s rating for.....apparently it holds more than your Pro Melt at about 17 lbs its at full capacity.

[Hossfly]

I’ve never weighed my Lee 4-20 pot when full to top with any alloy, but if it did weigh 20# there wouldn’t be room for any fluxing or stirring.

[Springfield]

Older RCBS Pro-melts can hold 22 lbs if filled to the brim. I have 2 of them. Maybe what you have is not a Pro Melt bottom pour. Got a pic of it?

[Burnt Fingers]

I've got both a PM and a PM-II and have no problems getting 20 lbs of melt in either one.

[Land Owner]

I am certain that its nameplate and instructions in its box (see image), assure it is an RCBS Pro-Melt.

I weigh my ingots on a beam scale that is locally "certified" with check weights made from a plastic bullet box into which lead boolits have been added. The boolits were weighed on a PACT Digital AND RCBS 5-0-5 Beam Scale. The sum of the component parts provides the "certified" check weights, and yes, they are accurate.

I have just emptied my Pro-Melt, twice, of 2/3 of its capacity. When I add 6#'s of lead-WW ingots and 1.92 ounces of tin each time (49-49-2 Pb-WW-Sn) to the 1/3 full pot, I reach maximum capacity, just below the lip. Any more and it will overflow. This Pro-Melt is no 20# pot.

https://i.postimg.cc/7YNVRjZn/RCBS-Pro-Melt.jpg

[bangerjim]

Why does it even matter?

When your pot gets to 50%, add more feed ingots. Works 100% for me! The liquid weight in the pot determines the outflow rate due to gravity, so keep it FULL! Whether is it 10%, 17#, or whatever. A low alloy level (and your casting techniques) will create casting problems with some molds.

You should do all your alloy ratio calculations with cold ingots on your digital scale, and not try to mix on the fly in a 700F+ pot based on it's level. That is NOT an accurate way of mixing alloys.

And preheat ALL your feed ingots on your electric mold heating plate to around 15-20F below liquidous temp of your casting alloy. That way, pot temp recovery is almost instantaneous.

Happy casting.

banger :guntootsmiley:

[Mk42gunner]

If you want to get specific, measure the volume of the empty pot then figure out how much that volume of your alloy weighs.

This could be as simple as volume of water vs volume of lead. IIRC lead weighs 23 pounds per quart.

Personally, I've never bothered. I just fill the pot and cast, I do my mixing of alloys in my smelting pot on the fish fryer.

Robert

[JonB_in_Glencoe]

Have you tried putting 20 lbs of pure Lead in the pot?
You mention WW...that's a lead alloy, not pure lead. WW alloy is less dense than Lead and takes up more space.

[Land Owner]

I never said I added feed ingots to create a specific alloy by guessing the level of the pot. All I have ever run though my pot is 49-49-2 Pb-WW-Sn. All of my feed ingots are 50-50 Pb-WW (I made them), about 3#'s pounds +/- a few ounces, each, weighed cold. Two percent (2%) Tin is added by weight to match the specific feed ingots added. The resulting alloy is "fine" for the shooting that I do and I am satisfied with it.

When the pot gets to about 1/3 full and the flow slows below a tolerable threshold, I take a break, and add feed ingots. Six (6) #'s is all that the pot, at that level, will take. Preheating them is good advice.

I was just wondering...about a 20# pot and whether the RCBS Pro Melt is one...it's not important.

[richhodg66]

Have you tried putting 20 lbs of pure Lead in the pot?
You mention WW...that's a lead alloy, not pure lead. WW alloy is less dense than Lead and takes up more space.

Would a difference in alloy make that big a difference? I know it can be significant difference in bullet weights, but three pounds or more out of only 20 seems like a lot. I don't doubt you just seems like a lot.

I have never used a pot that held more than ten pounds and have often thought about getting a bigger one, glad to know they aren't all what they claim to be.

[Petander]

If in doubt,measure.


My Pro Melt holds exactly a quart and math tells me a quart of lead weighs 22 lbs.

[JonB_in_Glencoe]

Would a difference in alloy make that big a difference? I know it can be significant difference in bullet weights, but three pounds or more out of only 20 seems like a lot. I don't doubt you just seems like a lot.

I have never used a pot that held more than ten pounds and have often thought about getting a bigger one, glad to know they aren't all what they claim to be.

That's a good question. I suspect it does make that big of a difference, especially when you work in the other variable.
The OP mentions "maximum capacity". That hasn't be defined by the OP. Is that full to the rim? or is that to a level he deems as safe and logical? I know I never fill my 20 lb to the rim. Wednesday, I cast about 800 boolits from a pot that was only half full and only used half of that, to accomplish the task ...filling the five small cavities of a 37gr boolit mold goes better with less head pressure. So in that instance, half full is the safe and logical maximum capacity.

[Land Owner]

I "fill" to within 1/8" of the rim, a capacity I deem "safe" on a stable bench. I will empty the pot, one day, and measure to the rim, then calculate volume and weight of lead. I was just observing "reality" and it "seems" that at about 2/3 empty, the pot "fills" with only 6#'s of alloy and 1.92 ounces of tin. I am pouring 50.5 grain (+/-) 22 Bator boolits, with a 2-cavity aluminum mold, by the thousands, and enjoying it. At "full" capacity, the bottom pour "gushes" its charge into the mold. I can adjust that - but won't. At about 2/3 of capacity, the alloy stream settles into an enjoyable pour. At about 1/3 capacity, I "worry" about overworking the electrical elements in the portion of the pot with no alloy, so I take a break and refill. This methodology is "working" for me.

[Larry Gibson]

Is the RCBS Pro Melt considered to be a "20#" pot? If it is, I can get no more than 10 weighed pounds of lead ingots in mine to reach its maximum capacity.

Which pots are actually 20# capacity - or are there any? Perhaps the name sticks because the pot, ingots, and supporting structure weigh 20#'s when full?...........All I have ever run though my pot is 49-49-2 Pb-WW-Sn.

You add 10 lbs of "lead" then add another 10 lbs of COWW + 2% tin?

[Mal Paso]

My Pro Melt holds 20lbs with room to spare, the Pro Melt 2 25lbs with room. Someone must have short sheeted the OP.

[Land Owner]

Larry - no...lead-WW alloy ingots and an additional 2% tin. I should edit my OP.

[44magLeo]

I might suggest either of two options, one is to fill the pot up full and cast ingots till the pots empty. Weigh those ingots.
Two is to empty the pot and start adding weighed ingots till pots full.
Either way will tell you how much your pot holds.

On my lee pot I measured the inside diasmeterr and depth of the pot. Using thse figuires and some simople match I found the pot holds 20 lbs. of lead when the pot is level full. When using it 17 or 18 lbs. is full enough. This gives my room to flux and stir if needed.
I think if you measured your pot empty and caslculated it's capacity you may find your pot my be 20 lbs to level full or maybe a bit more.
Leo

[alamogunr]

I've never thought about it. I've gotten old and by the time the pot is down to about 1/3, I'm ready to rest, so I add back the sprues and bring the level back up. A 5 min rest and I am ready to go again.

[Winger Ed.]

Maybe they call it a 20 pound pot if it can be filled to over flowing with pure Lead, and then weighed--- pot & all.

[Land Owner]

I'm going to measure the interior diameter (when hot), melt the pot, stick in a rod, and measure that for the depth to the rim, then calculate the theoretical weight of lead. I will report back.

[onelight]

The simplest way to check if you have a scale that will read in that weight range is weigh the pot empty and weigh it full .

[Mitch]

lol well now 2/3 full and add 6lbs of alloy seems that makes atleast 18lbs of lead in the pot.no matter seems it is working for you.if you want 20 lbs of bullets out of your pot go buy the 40lb magma lol

[Land Owner]

The pot is full of cooled alloy. Melting, dipping a steel rod in to the bottom, measuring the rod, measuring the pot diameter, and doing the math calculation:

Volume of pot (cubic inches) = Pi * (pot diameter/2) ^ squared * depth of pot (all measurements in units of inches) [Eq. 1]

Weight of Lead = 0.41 pounds per cubic inch [0.41pci]

Weight of pure lead = 0.41pci * Volume of pot [Eq. 2]



Unraveling this "math" in reverse, a 20# pot of pure lead has to be 20#/0.41 pci or 48.78 cubic inches.

I measure my pot diameter to be: 4 and 1/8" diameter and not more than 5.5" deep (cold, full, can't take apart to see where heating elements are, etc.). My pot is at most 73.50 cubic inches and most probably 48.78 cubic inches...so I am closer to the pin of a 20# pot, theoretically, than before I started this thread.

[Land Owner]

lol well now 2/3 full and add 6lbs of alloy seems that makes atleast 18lbs of lead in the pot.

Mitch, I emptied the pot to 1/3 of its capacity, not by 1/3.

[Burnt Fingers]

The pot is full of cooled alloy. Melting, dipping a steel rod in to the bottom, measuring the rod, measuring the pot diameter, and doing the math calculation:

Volume of pot (cubic inches) = Pi * (pot diameter/2) ^ squared * depth of pot (all measurements in units of inches) [Eq. 1]

Weight of Lead = 0.41 pounds per cubic inch [0.41pci]

Weight of pure lead = 0.41pci * Volume of pot [Eq. 2]



Unraveling this "math" in reverse, a 20# pot of pure lead has to be 20#/0.41 pci or 48.78 cubic inches.

I measure my pot diameter to be: 4 and 1/8" diameter and not more than 5.5" deep (cold, full, can't take apart to see where heating elements are, etc.). My pot is at most 73.50 cubic inches and most probably 48.78 cubic inches...so I am closer to the pin of a 20# pot, theoretically, than before I started this thread.

There's a BIG difference between 73.50 and 48.78 cubic inches.

Using your given measurements your pot would have 73.5 cubic inches, which would make it a 30 lb pot.

The heating elements on a Pro-Melt are not in the pot, they surround the pot.

[Land Owner]

Let me be clear(er). The pot is nearly full of alloy and cold. Not wanting to heat the alloy just to measure the pot depth, I measured the outside of the Pro-Melt housing, top to bottom, as a "cannot-be-deeper-than-this" number. So 73.5 ci is a big number, but is not representative of the "pot" that actually holds the alloy when it is liquid.

[44magLeo]

When you draw the pot down to 1/3 left, who do you determine it's 1/3 left? If it's at 1/3 and it's a 20 lb. pot you should be able to add 13 lbs. If you are only adding 6 lbs. you are not drawing it down to 1/3 left, you are drawing it down to 2/3 left.
The only way to now for sure is to heat the pot and measure the depth of the pot and the depth of the lead at what you think is 1/3 left. If you don't want to do either then I guess you don't really want to know.
Leo

[popper]

Try advertising an 17 & 3/4# pot.
Just fill with alloy you weigh before hand and get to casting.

[Alan in Vermont]

Is the RCBS Pro Melt considered to be a "20#" pot? If it is, I can get no more than 10 weighed pounds of lead ingots in mine to reach its maximum capacity.

Which pots are actually 20# capacity - or are there any? Perhaps the name sticks because the pot, ingots, and supporting structure weigh 20#'s when full?

Something weird is happening, my Promelt when filled to the rim and then emptied yields 22 pounds of small ingots.

[Land Owner]

Alan - yes. Just guessing.
44magLeo - I will quit the speculation and measure the pot when it is next molten.

[Frank H]

My lee 4-20 can melt right at 20lbs of pure lead and slightly less from ingots made from wheel weights.

[Mitch]

No matter where you are taking the pot down to when you stop to refill.Apples to Oranges.you may be only refilling 6 lbs but there is still 20bs or more in the pot when full.Me when I get to a point I stop to refill the pot I drop in 2 ingots 4lb each then put in the sprues>this works out pretty good for me with my RCBS promelt.I get it it would be nice if we could pour 20lbs of lead from the casting pot but not going to happen with any 20lb pot.my lee holds about 18lb and the Promelt holds about 22lbs.this is toltal lead in the pot from empty to full.Depending on the bullet and size of the sprue i need to pout i get about 6 yo 8lbs of bulllets from the Lee and 8 to 10lbs of bullets from the Promelt. Now if you want to cast 20lbs of bullets you need the Magma master pot it holds 40lbs.anymore I welcome the break between filling.

[Mike W1]

I'm guessing here but I suspect the bottom of the pot MIGHT be rounded like my Lee !0# is. Just put some water in the thing to the level you fill to and measure that water capacity. Simple matter to convert water volume to what an equal volume of lead would weigh! Also depends on how full you fill and I doubt anyone fills a lead pot up to the brim anyways. 18, 20 ,22 pounds what difference does it make?

[onelight]

Makes no difference to me :) I know my 20 holds a lot more than my ten.

[ioon44]

My 2006 vintage RCBS Pro melt holds 22 lb.