Lead Smelting Questions?

Status
Not open for further replies.

kcofohio

Member
Joined
Dec 16, 2013
Messages
5,342
Location
NW Ohio
I'm just getting into casting. I have been reading through "From Ingot to Target". And some here and there on the internet.
I smelted one pot of lead into ingots this morning. It was about 30' outside. I had a couple doors open, but I had a heater running in the garage. This afternoon it was in the upper 40s, so I decided not to run the heat. With the same doors open. About 10 minutes into this session, I heard a pop. It turned out to be the thermostat dial switch zapped and tripped the breaker. I'm getting a 17 ohm reading on the meter for the heat element.
My main question is, was the weather to cool out, that it taxed the melter too much? This is a new pot, 1st time using it today. I don't recall anyone mention the importance of the outside temperature when casting, only about ventilation.
Next, I only left about a half inch of lead in the bottom of the pot from the 1st session. Will that be too much added stress on the heat elements on the following heat up?
This should be straight scrap lead, but when I poured the ingots, there is some blue tint to the ingot surface. Too much heat? Or just a pour into cold molds?
Thanks for any guidance. I would rather not repeat this lesson if I caused it. :)
 
Ambient temp should not matter I have done in summer and winter.
I usually leave the pot half full or more as supposed to be easier on the heat element.

If a 120v unit 17 ohms comes in about 750 watts 7 amps should not trip a breaker.
May just have gotten a defective switch.
Check with the mfgr if no love see below.

You could order a cheap pid controller set and wire it direct to the element. Under 20$ and you get a digital temp display and control.
 
Possible it had to draw more to offset the cold. Also possible the breaker is weak, maybe going bead. At least it tripped. I've never had a pot trip a breaker but neither have I poured in that cold of temp.
Only idea I can think of is if some kind of insulation around it might help it not loose so much heat, if the cold is making it over work.
As far as venting you may not need open doors. When I pour in my barn I just make sure I'm working from the up wind side. I do open door if it's not cold. But as long as there is a draft being up wind works. Been pouring for 40 years and haven't had any ill effects.
Ive left mine full to empty and has not mattered. If it's working properly it should not matter.
If it is a bottom pour you need to keep the bottom cleaned so it won't clog it.
Use about 3/8 sq chunk of parifin to clean the lead. Stir it in when it's up to temp. It will smoke like crazy and may even flame but will burn itself out. Scrape all the junk out. You can put parifin in several times as you pour.
My dial goes 0-10. I start on 10 and let the lead get good and hot. Put in parifin and turn down to 8. First dozen pours go back in so the mold gets hot. Main thing they come out without wrinkles. Keep a 90^ pick handy and if the pour gets slow use it to clean the speckit. I went as far as drilling it out to a #40 (.098). Pours faster and doesn't clog up as bad but if you do that its even more important to keep the pot clean so you don't get a bunch of impurities in the pour.
 
A loose connection will cause more current draw, trip a breaker. Re-tighten all connections, even at the breaker panel, outlet. On the outlet make sure they used the screw terminals and not the push in one. Best to have the main turned off if you don't have the electrical insulated screw drivers.
 
I agree on the ambient temperatures in the same space not adding that much of a factor. There isn’t any start up draw it’s an on or off appliance I think.

You didn’t say if it’s an ongoing problem or a one off.

Does the pot turn or just trip the breaker.
Ambient temp should not matter I have done in summer and winter.
I usually leave the pot half full or more as supposed to be easier on the heat element.

I empty the pot after casting. First I’ve heard of element problems from an empty pot. Guess I’ll start leaving lead in the pot also. I empty for two reasons one thinking it would save time on the next melt and two if cooling attracted moisture trapping it between the lead plug and the metal pot sides.
 
You said that your new to casting, is your pot new? If it is I would be on the phone to who-ever made it and trying to get free parts shipped to me under warranty.

You did absolutely nothing wrong and the cold air had nothing to do with it. Heating elements are resistive loads and can only draw what they are rated for unless they ground out.

What brand and model is the pot?

If the heating element grounded out and didn't weld itself solid to the metal around it, you wont' see a ground on your meter because it grounded when it was hot and stretched out. Now it's cold

They usually burn off though.

If it's rated for 750 watts than, it can only draw 750 watts to heat in any condition. It like an incandescent light bulb. They're plugged into 15 amp circuits but can only pull the rated wattage or they would burn out immediately when turned on.

It blew your breaker so the something inside grounded out and maybe burned off.

Check your switch also for grounds, it should just be a simple thermostatic switch that is on or off, nothing in between.
If your switch is cooked you already know what is wrong.
 
I had ar15 amp breaker that would run my heat gun no problem all summer. 1500 WATT. Come 30 degrees or cooler outside it would trip the breaker in less than seven minutes.

The cold did increase the amp draw. This was corrected by confirming all outlets on the line ro check for reasonable load on the circuit. Confirmed the outlet only circuit had 20 amp outlets, and upgrading the breaker ro 20 amp. Wiring wax also in spec.

Note that an extension cord and length of cord will change draw also
 
I had ar15 amp breaker that would run my heat gun no problem all summer. 1500 WATT. Come 30 degrees or cooler outside it would trip the breaker in less than seven minutes.

Your breaker was already maxed out at 1500 watts, The OPs is barely in the middle of the breakers range of service. If his did draw a few amps more, so what.

I don't see how it could though.
 
Last edited:
Your breaker was already maxed out at 1500 watts, The OPs is barely in the middle of the breakers range of service. If his did draw a few amps more, so what.

Agree. By the math it looked as if I have 2.5 amps under max and the gun would not run on low which shows a 6.5 amp draw. Just another thing to consider. What about my previous homes setup led to the math not fitting the real world I'm unsure.
 
Thanks everyone! The pot is Lee's Magnum Melter #20 pot, no bottom valve.
The switch has a definite arcing mark between two of the plates. I'm not sure what, but something looks to be missing now. I can see what looks like a thin lead that was soldered onto a plate, but very little of it is left now. And heat marks on and around one of the insulating rings.
Before it popped, the pot had quite a hum to it. When it popped, my 1st thought was that moisture had gotten into the lead melt. But there wasn't any splatter.
Englishmn, thanks for the math, I was kind of lazy about looking for the formula. :)
tigthgroup, I can see what you're saying about the element settling after cool down to give a false positive, as it were. I'm hoping it is all in the switch, but I'll keep that in mind in case the switch doesn't completely fix it. I ordered one from Lee and only have to pay shipping. But I'm going to contact them tomorrow anyway.
Texas, I hadn't given that aspect of it much thought. But now that you say that, it makes sense and would probably save me some troubles down the line.
Thanks again everyone for your input. :)
I was hoping it wasn't a fair weather answer. As I want to get ahead on this casting thing before good weather gets here. When my free time gets reduced.
 
The cold did increase the amp draw.

Cold does not increase amp draw on a heating element, which is all a heat gun is with a small fan motor. The 1500 watt heat gun pulls 12.5 amps + what ever the small fan pulls, if it is a 120 volt gun (1500 watts divided by 120 volts). A breaker is only good for 80% of its rated capacity at continuous draw or 12 amps. Your 1500 watt gun had the circuit overloaded by itself.
 
Sounds like a defective component or moisture (condensation/frost) got involved and caused a short. We have a Lee pot and a Lyman pot we use for work stuff on electrical and pipeline jobs. I don't know exactly what alloy they're using or exactly what they do with it (lineman and pipefitter stuff, not my job), but I did notice the gear. I know it's run off a gasoline generator from 90 plus to sub-zero temperatures in less than ideal conditions, so I highly doubt the colder temperature caused any issue.
 
Sounds like a defective component or moisture (condensation/frost) got involved and caused a short. We have a Lee pot and a Lyman pot we use for work stuff on electrical and pipeline jobs. I don't know exactly what alloy they're using or exactly what they do with it (lineman and pipefitter stuff, not my job), but I did notice the gear. I know it's run off a gasoline generator from 90 plus to sub-zero temperatures in less than ideal conditions, so I highly doubt the colder temperature caused any issue.
More than likely a defective part. I saw no signs of moisture or oils inside the switch housing or on the switch itself.
 
One more question. I have looked for muffin bake trays or mini loaf pans as ingot molds. All that I have found so far have a non-stick coating on them. Will that coating become a problem with molten lead?
Right now I have foil trays, which work, but won't last many uses.
 
Calculating current draw from an ohm reading on a heating element is not totally accurate. The resistance in the element can change with temperature. Element temperature, not ambient.
 
Non stick is easy to get rid of. Just get it really hot with a torch or bonfire and it will flake away. I use an iron "corn stick" pan for ingots. Makes small flat ingots which also double as decoy and buoy weights for my other passions.
 
If a 120v unit 17 ohms comes in about 750 watts 7 amps should not trip a breaker.
May just have gotten a defective switch.
Check with the mfgr if no love see below.

You could order a cheap pid controller set and wire it direct to the element. Under 20$ and you get a digital temp display and control.

The PID controller is a very good idea. I bought one with a solid state relay for $14, delivered. For another $5, I got a high temperature thermocouple. At least on the Lee, the internal heater controller isn't worth a dang.

There is no need to directly wire to the heater element. Just turn the internal heat control up to maximum. That also provides a little bit of safety, since the heat could otherwise run away if the PID controller is turned on without the thermocouple in contact with the lead.
 
Status
Not open for further replies.
Back
Top