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Discussion Starter #1
My alloy is recovered metal from the firing point, plus a small amount of pure linotype to add a little hardness. I have recently discovered that my Lee melting pot is faulty and has been running at VERY high temperatures, far above the range specified in the instructions. I am not sure what the effects of casting at very high temperatures are, but this may be contributing to the problem.
Has anyone got the engineering know how to expalin what the effects of using very excessive temperatures for melting and casting are? at number 4 on the thermostat setting the alloy has an orangy glow to it. The mould overheats very quickly and may have actually been damaged by the excessive temperature.
The melting pot is only a couple of months old and seems to have been faulty from new.
 

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I made your post into a new thread, as it didn't seem much related to cast bullet tumbling.

Sounds like the thermostat failed. Send it back to Lee.

Overheating can damage molds, as you noted. If they are Lee molds, I would send them to Lee with the pot for checking out. Tin will oxidize out fast at that temperature and a melt that hot won't flux easily with the usual materials, so you can get some inclusions in the bullets that ruin their balance. The seriously overheated mold will cast bullet too big.

At one atmosphere vapor pressure, lead needs to be heated to over 3000 degrees to evaporate. That's yellow hot, so you aren't there yet. I doubt the Lee pot could even approach that. It if looks orange, I would guess you may be at around 1500 degrees, depending on the lighting conditions?
 

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I sure can't imagine my Lee pot getting getting bullet alloy anywhere near "orange hot" without melting the power cord or tripping a circuit breaker?

Do your hear the melter cycle on and off? The power cord on mine is no more than 16 gauge wire. Good for no more than 1500 watts at full duty. The high-tech polymer(plastic) insulation should be getting a bit soft and sticky if you are above that.

Cheezywan
 

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Could be the dross on top of the melt turning funny colors, just a thought.
 

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If my Lee pot got up to 3,000 degrees the pot would melt away. The melting point of Aluminum is is about 1,225 degrees F. Some aluminum alloys require more heat, but no where near 3,000 degrees. Once in a while I do some small foundry work and we do aluminum and bronze.

Jerry
 

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That's a good point. My Lee doesn't have any aluminum in direct contact with the melt, though it's in the outer insulation sheathing. If he were getting orange hot, though, that skin would be at risk where meets the steel lip of the inner liner. I was wondering how it got that hot, myself? I think Mike is on to it, and he is seeing oxide film color rather than orange heat.

That goes back to the question about whether he hears the thermostat operate? If not, it's a defect.

I should also mention that my Lee pot's thermostat would let it run up and down over fifty degrees. That's because it samples temperature inside the control box through the heater tubing, which is inadequately linked. That was a bit much, so I replaced it with a thermocouple controller back in the mid-80's.
 

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Discussion Starter #7
I have contacted Lee and a nre thermostat is on its way to me. They are really helpful at Lee.

The thermostat doesnt really click much at all, I think it is stuck in the ON position so runs permanently.

It is the 240 Volt model for use here is the UK, so cable etc. is presumably all beafed up. There is no sign of the cable overheating.

Bullets were very over size which I agree is no doubt due to the temperature problem. The orangy glow was generated by the alloy itself and no amount of skimming the surface removed it.

I do not know how high the temperature would have got to if I hadn't turned off the power, or what would have failed first, I'm just glad there was no serious failure that could of injured me.

I'll let you know if the new thermostat solves it.
 

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Also remember that steel melts below 3,000 degrees. I am a blacksmith, and I can get steel up to 2600 to 2800 degress F and it will melt away. I normally work in the 1,900 degree F range, it is workable at that temperature, so think of a dense liquid sitting in a thin steel shell.

Jerry
 

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One thing that was not mentioned is the danger of the lead fumes.....Anything over 900 degress will cause your lead to put OUT SOME VERY DANGEROUS FUMES......Get your self a thermometer....Cast in a well ventalated area.....Good luck and be safe....
 

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I have two Lyman dial type thermometers and always keep an eye on them. Over the years, I don't I have gone over 750 degrees when melting lead.

Thanks for that warning and we always can be more cautious.

Jerry
 

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Bulletmaker,

Do you have a reference for the 900 degree number? I've seen everything from government documents claiming even electronic soldering with an iron tip below 500 degrees to nothing short of the 3180 degree boiling point causing serious vapor. I don't believe either extreme, and keep looking for some reliable source or a vapor v. temperature chart for one atmosphere pressure.
 

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Sorry I have no proof of this...Only what some of the older casters have passed on to me
over the years....But I followed their advice anyway...Why would anyone have to cast over
say.700 degrees in the first place anyway...John
 

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the outside. Air movement that is sufficient to carry away the wisp of smoke from an extinguished match is generally considered sufficient ventilation. Lead melts at 621 degrees (F). When lead is molten, it releases minute amounts of vapors at a progressive rate as temperatures are increased. Harmful levels of lead vaporization are believed to occur at elevated temperatures above 1800 degrees (F). Only lower temperatures between 700-800 degrees are normally needed to cast lead hobby parts. Most melting equipment sold to hobbyists will not raise temperatures much above 900 degrees. Minimize vaporization by operating melters at the lowest temperature ........I never knew about the 1800 degrees...But I still believe in the 900 or more being un safe...john
 

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Discussion Starter #14
The new thermostat has not yet arrived from Lee, so no casting going on at the moment.

I have been reading up on melting alloys and it does appear that the excessive temperarures would have caused all sorts of problems with the metals in the alloy, depending on which author you read.

When my pot was at well over 900degrees the tin would probably have been destroyed and I guess the lead fumes would have been excessive. Although I was working with reasonable air circulation I guess there would still be some risk.

With the pot failing to turn off I assume the temperature would have just kept going until some part of the pot failed. I am very surprised that the pot left the Lee factory with this fault. I'd be interested to hear if anyone else has had this problem.

The mold is written off, the excessive temperature must have warped the aluminum blocks as I cant get the two halves to line up and there is a wafer of alloy flowing under the sprue plate. Can this be rectified does anyone know?
 

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Discussion Starter #15
I have recently noticed that the thermostat in my Lee melting pot is marked up with "6.7A/120v".

I'm im the uk where our electricity supply is 240 Volt. I am no expert, but would this fact explain why the pot is overheating and the thermostat isnt cutting out the power when the pot is up to temperature?

I assume 120volts is the voltage in America.

Could anone come back to me and confirm if this explains the overheat problems?
 

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I suppose it could be the problem...120 is the standard here in the US...But it seems like your 220 would burn up the pot...Then again maybe not...Get a thermometer to be sure of what it is....Just to be safe...
 

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Yes, that would be the standard wall voltage here. I would sure send Lee an email and ask them if you got the right one. Maybe it needs converted? Some laptop power supplies will run on either, FYI, but they are usually marked as such. Some computer power supplies as well, but those are usually equipped with a physical switch in the back....
 

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Discussion Starter #18
alloy STILL overheating UK Lee Melting pot

The good news - the new thermostat arrived from LEE
The bad news - the pot is still overheating - It got up to 1157 Fahrenheit today, and thats only at setting 6 !
I gradually turned the setting down one number at a time, waited 10 minutes each time and retook a temperature reading, it wasnt until I had the knob down at setting number 2 that the heating element stopped glowing and the temperature dropped a little. Still operating at around 1000 degrees.

The replacement thermostat was marked 120 volt, the same as the original part, but LEE Precision assure me this is ok ???? I'm not so sure.

Does anyone on here use a melting pot in the UK, Could you check & see what is on your thermostat, you need to take it off to read the markings engraved in the top. mine says 120 volts.

Does anyone have any suggestions or advice? The high temperature caused a lot of scum to form on top of the pot, and presumable a LOT of lead fumes, how dangerous would they have been ?

Any ideas ?
 

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OK. Time to play detective. The thermostat won't care except that it's contacts would probably have issues with arc-over if the load were inductive. But it isn't. It's resistive.

Next step is to get either a clamp-on ammeter and measure that the current going into the pot, or else to, get an ohmmeter and measure the resistance at the wall plug pins. My Lee pot is ancient, but the label clearly shows it is 500 Watts. For 230 volts that will draw just under 2.2 amps and will have a resistance of about 106 ohms. For 120 volts, though, it would be 4.2 amps and 28 ohms.

From the heat you are seeing, I am suspicious they may have givne you a 120V heating coil heating coil instead of a 230? That would draw 8.2 amps and produce almost 1900 watts. The heater couldn't take that forever, but it could take it for awhile. That exceeds the thermostat contact rating and could pit the thermostat contacts enough to make them stick?
 

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I'd have to suspect that the thermostat was and still is wired such that the heating element is not being regulated by the thermostat.

I've never replaced one though. Are there three lugs or only two?

If three(and one is un-used) move the wire from the element to the not used lug?

I'm thinking that it may have been mis-wired from the factory, and that you have now duplicated the factory's mis-wiring by just replacing the parts as you saw them?

Were the instruction clear with the replacement parts?

Cheezywan
 
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