bottom pour pot guys

[gofastman]

what temp do you cast at?

I have a 10 and 20 lb LEE pot, and mostly LEE six banger molds.

I find the best bullets come out of them if the lead is HOT, like 800* or more

My alloy is kind of unknown right now, I mooved and it all got mixed up.
but my best guess is that is about equal to clip on wheel weights+2% extra antimony+2% tin

[imashooter2]

Most of my molds do well at 680 - 700. My spout freezes at ~640. I have a few molds (in particular an old Lyman 429421) that like to run hotter. This is why casting notes are important.

[rmatchell]

My Lee 6 cavity molds also seam to like to run hot I always figured it was because they are aluminum.

[Dave C.]

725-750

[500MAG]

I try to keep it around 700. Pure lead I run at 750.

[snuffy]

Without a lead thermometer, you're just guessing. Even WITH one, you'll find the lee 20# pot makes a huge temp swing from on to off, then on again, as much as 75 degrees. Then, as it empties, the temps do a gradual climb to a hotter high temp. The numbers on the top are simply a guide, they mean nothing in the way of degrees of heat.

It sounds like you don't have the mold hot enough, IF you are actually casting at 800 degrees. Mold temp is much more important than the alloy temp.

The ONLY solution to regulating any electric pot is a P.I.D. controller. Do a search for PID in the casting equipment forum, to see what it's all about.

[Rex]

680-700 on my Lyman lead thermometer

[gofastman]

I have a PID controller and a supplementary RCBS thermometer.


Mold temp is much more important than the alloy temp.
and what should that be targeted at for my LEE 6 cav's?
I plan on getting one of Swede"s (NOE) mold thermometers soon here.

[dragonrider]

I cast mostly at 750.

[David2011]

The mold temp is everything and Lee molds are hard to keep hot. Your pace determines the mold temp. Of course, if the pot isn't hot enough then the mold won't get hot enough but you can vary the mold temp over a huge range by varying how long the sprue hardens and how much time passes as you drop the boolits and refill the mold. It's easier to keep the mold hotif you use sprue plate lube so you don't have to wait for the sprue to harden.

David

[gofastman]

The mold temp is everything and Lee molds are hard to keep hot. Your pace determines the mold temp. Of course, if the pot isn't hot enough then the mold won't get hot enough but you can vary the mold temp over a huge range by varying how long the sprue hardens and how much time passes as you drop the boolits and refill the mold. It's easier to keep the mold hotif you use sprue plate lube so you don't have to wait for the sprue to harden.


ok, I kind of expected that as my 240gr .44 mold is a lot easier to work with than my 105gr .38 mold

I have a hot plate I pre heat the molds on, but right now with no thermomiter its just a guessing game.

I guess Im wondering if there is a specific number I should be aiming for... 300*F maybe?

[JonB_in_Glencoe]

I'll answer your question...kind of.

Mold temp is more important. While I don't have a mold thermometer, I can kind of tell by how long the sprue stays molten, although that indicates more of the sprue plate temp, also the shineyness/frostiness of the boolits can give a good indication of mold temp.

I try to cast with the melt is as cool as possible and still get boolits lightly frosty, instead of shiney and typically the sprue puddle will freeze in 3 to 6 seconds.

What's the pot melt temperature set to ?
well that'll depend on the type of mold and the number of cavities and how large the cavities are and how fast you are casting...and of course the alloy too.

one example:
I cast alot of Lee's 358-125 RF in a 6 cav. mold. with an alloy of 50% WW and 50% range scrap. Starting with a preheated mold and once I get my rhythum,
I maintain the alloy temp between 650º and 675º (read by a Lyman thermometer)

I rarely run the pot above 725º...maybe for a 22 cal aluminum mold.

800º just seems way to hot...but I've heard that some get good results doing that, so I won't criticize.
Jon

[Bigslug]

I am about to start using a Harbor Freight "laser pistol" thermometer to check mold temps, but thus far, I've got to say "hotter is better"

Since I never do anything the easy way, my first mold was RCBS's single cavity 265 grainer for the .455 Webley. This is a nose-poured, hollow base bullet that gave me fits the first time I tried to cast with it because the base WOULD NOT fill out. For the most recent casting I did, I cranked the dial on the Lyman pot to about "9" and left it there, keeping the pot full with fresh ingots as I went. About 700 beautiful slugs with less than 1% rejects and no freezing of the spout were the result. I would guess the contents of the pot to be in the the ballpark of 800 degrees.

[edler7]

700-725, depending on the alloy.

Lee 20 lb pot controlled with a PID.

[popper]

Same as elder7 I use the PID probe to check mould temp, > 400F before I start casting. A few pour and the sprue is up to temp. My moulds are all aluminum.

[MikeS]

I usually cast at 660F with my Lee 20lb pot. I use a PID, so the temp isn't a guess. Some moulds like the pot slightly hotter, but most work just fine at 660. Mould temp is the important one, not the pot temp.

[runfiverun]

try a mold temp in the 375 range

[geargnasher]

So far nobody's even come close.

The answer to "how hot should my alloy be" is very simple: 100 +/-25 degrees hotter than the full-liquidus point of the alloy. This is universally true of any type of boolit-casting alloy. That might be 575 degrees with Linotype and 750 with pure lead. IT TOTALLY DEPENDS ON THE ALLOY COMPOSITION.

Mould temperature target is variable, depends on ambient temp, alloy, alloy temp, mould style, material, mass, number of cavities, etc. Judge temp by fillout, and control temp with pace and sprue puddle size.

Gear

[David Bachelder]

I keep the pot at 750 or so. I also use Lee molds and have had good luck with them. Once I get the molds hot enough the casting goes well. I have also gotten the molds too hot.

When you see wrinkles the mold it too cold.
When you see frosting the mold is too hot.

Simple as that.

Works for me.

[HDS]

I run mine at 700-720F. I tried running today at 680F but it wasn't working out very well, spout refused to flow at that temp, at least regularly, it'd sometimes flow, other times not. I use a mix of wheel weight analogue I've alloyed myself and 50-70% pure lead.

[geargnasher]

I keep the pot at 750 or so. I also use Lee molds and have had good luck with them. Once I get the molds hot enough the casting goes well. I have also gotten the molds too hot.

When you see wrinkles the mold it too cold.
When you see frosting the mold is too hot.

Simple as that.

Works for me.

750 with what alloy? What is it's fully melted point? To say that you keep it at "x" temperature is meaningless to someone else, with a different alloy which has a different melt point. So say someone else, with a different alloy, takes your advice and then wonders why (as a possile example) they get excessive dross formation on the melt. "But so-and-so said to put the pot at 750" he might say. Well, did either one of you know the significance of alloy temperature? This is how confusion, frustration, and internet myths get started, because the alloy in your pot, my pot, and someone else's pot are all different, and don't react the same way to temperature. See what I mean?

The MOST important temperature is mould block temperature, but alloy temperature maintained as I mentioned above will minimize dross formation, tin loss, and other issues.

Gear

[RobsTV]

So far nobody's even come close.

The answer to "how hot should my alloy be" is very simple: 100 +/-25 degrees hotter than the full-liquidus point of the alloy. This is universally true of any type of boolit-casting alloy. That might be 575 degrees with Linotype and 750 with pure lead. IT TOTALLY DEPENDS ON THE ALLOY COMPOSITION.

Mould temperature target is variable, depends on ambient temp, alloy, alloy temp, mould style, material, mass, number of cavities, etc. Judge temp by fillout, and control temp with pace and sprue puddle size.

Gear

That is the only answer that worked for me.
Once I stopped listening to 700+ degree type answers, and used the 100 degree higher method, everything fixed itself.

My spout stops flowing at around 425. (Tel-tru 2 inch Dial 5 inch)
Normal casting with the "alloy I use" is 500 to 525 for all bullets from .311 to .501.
Prefer shiny to frosted (when possible), as long as have good fillout, so choose the lowest I can get these results at.

Alloy ingredients work out to be about 2.22sn 4.32sb .08as 93.4pb = 13.2 BHN (confirmed with Lee hardness tester)

Of course when heat treating, this also requires oven to be kept lower than what most use (this is done with a different thermometer, and confirms the low melting point when they slump sooner than I wanted).

Using the following Lee 2 cavity molds, and the thought that they must be hot doesn't work here.
356-120-TC
365-95-1R
358-158-RF
401-175-TC
C312-185-1R
C501-440 RF

All the above come out perfect at 500 to 525, with the C501-440's always a little more frosty compared to the rest.

[geargnasher]

"Frosty" or shiny is a product of mould temperature, not pot temperature, and is the primary visual cue (other than sprue puddle freeze time/rate) to determine mould temperature. You can make frosty boolits with alloy barely hot enough to pour if the mould is hot enough, and you can make shiny, wrinkled, half-filled boolits with 800-degree wheel weight alloy and a mould that's hot enough to burn you, but not nearly hot enough for casting good boolits.

Gear

[RobsTV]

Besides the lower than most use temperature, controlled speed is what is keeping the molds at desired temperature and affecting shiny or frosty. The 500 boolits are always frosty only because I do not like to wait too long between cycles, and that mold really retains the heat. Spru puddle is also what I use to time things, and it drastically changes with speed of casting. For most molds, 5 cycles a minute is close to the rate I try to run. The 500 falls to around 2 or 3 cycles per minute based on spru puddle.

I also frequently toss spru's back into melt during casting, to keep melt temp as low as I can get away with. This gives my molds a brief cool down period as well, which helps reduce frosting (except in the 500).

[gofastman]

The answer to "how hot should my alloy be" is very simple: 100 +/-25 degrees hotter than the full-liquidus point of the alloy. This is universally true of any type of boolit-casting alloy. That might be 575 degrees with Linotype and 750 with pure lead. IT TOTALLY DEPENDS ON THE ALLOY COMPOSITION.

sounds reasonable, thanks!
I wonder if this could be used to sort of decipher my alloy as well. :Bright idea:

[geargnasher]

I highly suggest getting a copy of The Lyman Cast Bullet Handbook, 3rd edition, and read the text. You'll learn a LOT.

Gear

[Griz44mag]

All this talk about pot and mold temp. What did our forefathers do? They melted lead over a wood fire, and cast in molds that were warmed on the embers and hot rocks by the fire. They cast by the way it feels. I do use an electric pot, but cast at a pace and temp that works for the mold. If the sprue frosts over in 3-5 seconds, everything is just fine. Too long? Turn up the heat, cast faster. Too fast? Turn it down. Slow down and give the mold a little resting time between casts. Get into the rythm, the mold and the purty bullets dropping out will tell you how good or bad you are doing.

[sw282]

l use a #20 Lee bottom pour pot. l fill it to within 1/2" of alloy . Temp is usually around 8 on the dial. l cast til the pot has about an inch of alloy remaining. l then flux. Skim off the dregs and refill the pot. While casting l allow the sprues to fall back in the pot. No lead splash because theres trash from refilling the pot leaving a thick skim over the alloy. l have recently increased both quality and quantity of my boolits since getting a couple of Hensley & Gibbs molds off the net. Using my set rhythm makes it much easier to cast with these GREAT molds compared to my Lyman/RCBS/Lees

[craig61a]

Just getting started so I'm no authority. I cast about 700 boolits this weekend with a Lee 10# pot (first time). I ran between 750 - 800 degrees. I started pouring when the temp got to 800 and adjusted the control a little at a time so I didn't get much over 800. As I continued the temp sometimes would drop down to 750 but the quality of the bullets was about the same. I did run a little over after the sprue filled and kept the opening only about 1/2" of less from the spout and got good fillout. I'm already considering getting something bigger and getting a cheap PID/Thermocouple/SS relay... but that's yet another project.

[RobsTV]

.... I did run a little over after the sprue filled and kept the opening only about 1/2" of less from the spout and got good fillout. ....

Another good point. Distance from spout to mold. I try to keep it around 1/4" with my low temp alloy. Further away had bad results as the melt cooled a little on its way into mold.

I think best melt temperature, mold temperature, spout to mold distance and timing rhythm are best determined by simply spending an entire day practicing and taking notes. Stick with only one mold. The beauty of all of this is that you can not fail. Simply toss them all, both good and bad, back into pot and keep testing and making notes on the results.

[John Boy]

I am about to start using a Harbor Freight "laser pistol" thermometer to check mold temps, but thus far, I've got to say "hotter is better" You wasted your money with a Non-Contact Infrared Thermometer with Laser Targeting. It only measures the surface tremperature.

Spent 20 bucks and buy a Tru-Tel bi-metal thermometer where the probe measures the temp of the melt IN THE pot
http://www.teltru.com/p-272-big-green-egg-primo-grill-dome-kamado-replacement-thermometer-lt225r-5-inch-stem-2001000-degrees-f.aspx

re: Casting temperature ... the mold will determine what temperature you should be casting at. It will vary, size of the blocks and bullet cavity. Start at 700 and work your way up in 10 degree increments. When the bullets are filled out after a 5 second pour and the sprue puddle frosts between 5 to 10 seconds (depending on alloy and bullet weight) ... write it down and keep in your mold storage box

From My Experiences - close to 200 molds: 22 LR to 50-70

[Alan in Vermont]

You wasted your money with a Non-Contact Infrared Thermometer with Laser Targeting. It only measures the surface tremperature.

Spent 20 bucks and buy a Tru-Tel bi-metal thermometer where the probe measures the temp of the melt IN THE pot
http://www.teltru.com/p-272-big-green-egg-primo-grill-dome-kamado-replacement-thermometer-lt225r-5-inch-stem-2001000-degrees-f.aspx

The member who posted about trying a laser thermometer was wanting to use it to check MOLD temps, not the temp of his lead pot. Seems like it should work acceptably in that application.

[geargnasher]

The reason for establishing molten alloy temperature at 100 degrees above the full-liquidus point is because doing so will balance the oxidation rate of the metal (which increases with heat) with the amount of extra heat energy absorbed by the tooling. If the tooling sucks up and dissipates a lot of heat (like a Lee commercial mould does, or a heavy brass mould) you may need to go 125 over full liquidus. Small-block, iron moulds with large cavities overheat easily and need cooler alloy poured into them, so the pot can be dialed back quite a bit.

So, pot temperature is based on a constant that's related to the alloy compostion and properties, not the mould primarily. Ambient temperature has more effect on which end of the suggested alloy temperature range works best for a given mould than anything. Mould temperature is controlled by casting speed, and casting speed is related to alloy temperature, thermal mass of the mould, and ambient temperature.

There are a variety of excellent reasons for establishing alloy temperature based on melt point and relying on casting technique to maintain mould block and sprue plate temperature, but those to whom it's important will discover this for themselves eventually.

Gear

[rintinglen]

I don't worry about temps--I worry about results.
I went through a phase where I was bent on getting stuff precisely right. I bought a hardness tester, a thermometer, bought some foundary metal of guaranteed alloy. I tested and measured, monitored and examined, convinced that I was on my way to one hole happiness. I was contemplating a PID controller that would just about double the cost of my lead pot when a bit of shooting told me that something was wrong.
My lever actions couldn't tell the difference. Neither could my revolvers.
My carefully measured, heat-treated, weight sorted boolits shot very little better than my older stuff.
It quickly dawned on me that my "precision" was more of an affectation than an effective means of controlling my boolit's quality. Careful attention to the finished boolit pays more dividends than all the thermometers in China. Wrinkled, poor fill out--clean the mold and then speed up your casting. Frosted, dimpled waists--slow down. Well filled out, sharp corners, no inclusions--bingo, we have a winner.
Given that the specific alloy composition is seldom known to the caster, it makes sense to focus on the end product rather than the process, because the "595 degree" mark that got you good boolits the last time may be way too cold for the antimony rich-tin-free stuff you have now. Given the variance in metal composition, and lacking an conomical means of determining that variance, let your boolits be your guide.

[geargnasher]

Obviously, attention to detail when casting is only as good as the same level of knowledge and precision applied to the rest of the loading process.

If sub-moa groups at 100 yards is your goal, you'll need to do things very much right. If minute-of-milk-jug at 15 feet is the goal, then it doesn't matter much.

Gear

[Bob Krack]

Gear has had several very informative posts in this thread and he does know what he is talking about.

I have a casting thermometer and only use it as a general idea of temperature of the alloy. I usually record the temperature of the melt as soon as the spout will flow. I try to maintain temperature slightly above that point.

I like shiny boolits and increase the temperature 1/4th of a number or so until I get the first signs of frosting and then turn the dial down the last 1/4th of a number.

I do not have the dexterity to manipulate the speed much any more. Actually becoming more selective which boolits I cast for anymore. Tremors starting to set in and I'm starting to feel much older than my age.

Back on subject - actual temperature means nothing absolute about casting. I have to run things hotter (by thermometer) in the man cave in middle winter than in warm/hat weather.

Bob

[Gunslinger1911]

I'll throw in my .02 - I run range scrap with a couple % antimony and maybe 1% tin. I smelt something like 500# in a run so I have pretty consistant alloy for quite a while.

My Lee 20# pot spout freezes under about 700 deg.

I run the melt around 750. For me, mould temp is everything, some moulds it's not too picky - Lee 6 bangers with a "simple bullet style" (.45 230g RN or 10mm TC) fill out nice running two or three moulds at a brisk pace.

A Lee .500 SWC at 440g 2 banger - I fought for a while untill I drilled it for a temp probe - can't remember the temp off hand, but I have to let it cool a while between pours.

A Mihec brass 2 banger .45 / 270 SWC is REALLY picky about temp !

As was said, best bet is to take a day, mess around with mould temps, you'll hit the sweet spot eventually - really - some times just takes a while.