Thermodynamics of melting lead

[barnfrog]

Probably misusing that term, but it'll take the grammar police some time to get a warrant so I'm safe for a little while at least.

I'm slowly working my way into trying my hand at casting my own bullets. Lead melts at 621.5 degrees F. I have an old electric hot plate that, according to the thermal imaging camera at the firehouse, will reach at least 750 degrees F. (It might get hotter, but I turned it off when it reached 750.) Will that be hot enough to heat whatever vessel I use, melt the lead, and get it hot enough to cast bullets? Or will there be too much heat loss for it to be a useable heat source for that purpose? In the "Bullet Casting 101" chapter of From Ingot to Target, Fryxell says to set the thermostat of one's melting pot to 750, so it seems like the hot plate is at least close.

Antecedent appreciation for any and all advice or admonishments.

 

[.38 Special]

It might work, but it won't be terribly fast. Even boiling a pot of water can take a while with those things. I'd use a small pot with good heat retention properties. A cast iron pot holding five or ten pounds of lead might be ideal.

Personally, though, I'd hold out for either a proper electric pot, or a propane burner.

 

[troy fairweather]

No

 

[41 Mag]

I usually run my Lee 4-20 at around 730'ish using a PID controller with a thermocouple inserted into the pot.

Not sure what the depreciation will be when you throw a SS or steel pot on top, but you can assist it using a propane torch to heat up the lead from the top.

 

[hso]

Pot dependent. Thin steel or cast iron, perhaps. Some slab or multilayer pan might have the aluminum or copper melt at those temps.

 

[GeoDudeFlorida]

Probably misusing that term, but it'll take the grammar police some time to get a warrant so I'm safe for a little while at least.

I'm slowly working my way into trying my hand at casting my own bullets. Lead melts at 621.5 degrees F. I have an old electric hot plate that, according to the thermal imaging camera at the firehouse, will reach at least 750 degrees F. (It might get hotter, but I turned it off when it reached 750.) Will that be hot enough to heat whatever vessel I use, melt the lead, and get it hot enough to cast bullets? Or will there be too much heat loss for it to be a useable heat source for that purpose? In the "Bullet Casting 101" chapter of From Ingot to Target, Fryxell says to set the thermostat of one's melting pot to 750, so it seems like the hot plate is at least close.

Antecedent appreciation for any and all advice or admonishments.

That’s how I started out in 1978/79, using an old hot plate and a cast iron stew pot. I also used a ladle and candy thermometer. No, it is NOT an ideal setup but it made some darned good bullets, two at a time, for many years. Eventually I made a fancy bottom-spout pot and made a controller using a breadboard and parts from Radio Shack but I didn’t get to enjoy it for very long thanks to some job shuffling and multiple moves. To be honest, the cast iron pot and ladle worked fine. I wasn’t exactly mag-dumping my Ruger Blackhawk.

 

[AJC1]

Hot plates are good for preheating molds, but a propane burner is better for ladle type pours due to rapid heat loss. You could try it, but I bet you get a ton of wrinkled bullets. The base melting temperature of lead isn't really helpful as you most likely aren't casting miniball and more likely using antimonyal lead which needs more heat

 

[lightman]

You probably will not be happy with a hot plate. Buy a proper bottom pour pot and be done with it.

 

[hdwhit]

Whether it will work is dependent not only on temperature but whether the hot plate can generate enough heat so that you are adding heat to the combination of the pot and the lead faster than it is being transferred out of the pot and the lead into the surrounding air.

I think you can probably get it to work, but the amount of lead and the size of the pot may need to be small enough that the experience may not be satisfying.

Any way it goes, you're going to learn a lot from the experience. Please share what you learn.

 

[thump_rrr]

Probably misusing that term, but it'll take the grammar police some time to get a warrant so I'm safe for a little while at least.

I'm slowly working my way into trying my hand at casting my own bullets. Lead melts at 621.5 degrees F. I have an old electric hot plate that, according to the thermal imaging camera at the firehouse, will reach at least 750 degrees F. (It might get hotter, but I turned it off when it reached 750.) Will that be hot enough to heat whatever vessel I use, melt the lead, and get it hot enough to cast bullets? Or will there be too much heat loss for it to be a useable heat source for that purpose? In the "Bullet Casting 101" chapter of From Ingot to Target, Fryxell says to set the thermostat of one's melting pot to 750, so it seems like the hot plate is at least close.

Antecedent appreciation for any and all advice or admonishments.

Are you melting pure lead?
Wheel weights melt at 505F.
My PID controllers on my Lee 20lb pot and my 40lb pot on my Master Caster are both set at 630F.

PS: That's a really cute kitty.

 

[dredd]

That’s how I started out in 1978/79, using an old hot plate and a cast iron stew pot. I also used a ladle and candy thermometer. No, it is NOT an ideal setup but it made some darned good bullets, two at a time, for many years. Eventually I made a fancy bottom-spout pot and made a controller using a breadboard and parts from Radio Shack but I didn’t get to enjoy it for very long thanks to some job shuffling and multiple moves. To be honest, the cast iron pot and ladle worked fine. I wasn’t exactly mag-dumping my Ruger Blackhawk.

Similar process for me, but not that long ago. I didn't have to go to Radio Shack. I also wasn't smart enough. LOL
I still keep that thermometer handy.
When I was happy with the casting experience, I picked up a bottom pour pot and moved forward.

FYI: Bottom Pours are not perfect. They still have to be cleaned out once in awhile.
They will develop a drip.

I still use the burner and cast iron pot for rendering small batches of lead.

 

[barnfrog]

Are you melting pure lead?
Wheel weights melt at 505F.
My PID controllers on my Lee 20lb pot and my 40lb pot on my Master Caster are both set at 630F.

PS: That's a really cute kitty.

Haven't got any lead yet. I have a couple molds that I got as part of an estate sale lot, and I figure a small cast iron pot can't cost too much. If I decide to proceed down this lagomorph lair, I'll probably buy some commercial alloy to start, and find a ladle on fleabay.

That's our three-legged cat, Kramer. Dumb son of a gun got hisself runned over. Crawled home a week later to show us his crushed pelvis. Were I in his place, I would have curled up in a ditch and cried until I died. He's nothing if not tough.

 

[stormshrike]

Today at Miday you can get a Lee Pro 4 20 bottom pour for $72+tax (free shipping) with RELOADING050523 code. Good price for these days, and if you don't like it resell it. Just my opinion, but you'll improve your odds of successfully learning to cast (and enjoying it!) with a tool made for the purpose.

 

[Slamfire]

I do not think you will be happy with a hot plate. Sure the hot plate will get to 750 F or so, but something else that matters is the amount of heat the hot plate creates. As you heat that lead, it gives off heat to the surroundings. Sort of trying to fill a bucket that has a hole. You need a lot of heat to melt 10 or 20 pounds of lead. Maybe your hot plate can do it, but it may be very, very slow in doing so.

 

[barnfrog]

I do not think you will be happy with a hot plate. Sure the hot plate will get to 750 F or so, but something else that matters is the amount of heat the hot plate creates. As you heat that lead, it gives off heat to the surroundings. Sort of trying to fill a bucket that has a hole. You need a lot of heat to melt 10 or 20 pounds of lead. Maybe your hot plate can do it, but it may be very, very slow in doing so.

That's what I was wondering. Intuitively I figured the coil in the hot plate wouldn't necessarily heat objects on the hot plate to the same temperature, but I don't know how much heat is lost to the surrounding environment. Obviously it depends on the vessel, the alloy and how much material one tries to melt at once.

 

[mdi]

I have read of some newer casters using a hot plate for melting bullet alloy, but they eventually (soon) went with a dedicate casting pot. I started with a Coleman stove and a stainess steel pot (2 quart?) and the pot seemed to heat the alloy quickly, a bit faster than a cast iron pan/pot. If your hot plate is getting to 750 degrees, then it should work, but it may take a while. I sometimes use a single burner propane stove for alloying/cleaning which will melt 15-20 lbs in a steel pot (1/4" thick walls) in about 15-20 minutes. I'd start with about 10 pounds or so of alloy and try a hotplate. Might get you started in one of the most satisfying/fun parts of do it yerself reloading...

 

[Docendo Discimus]

Will that be hot enough to heat whatever vessel I use, melt the lead, and get it hot enough to cast bullets?

Yes it will probably melt the lead. It may also frustrate you to the point that you give up on casting altogether. Casting is all about timing and temperature control. If the alloy is a little to cold you will get bad fill out and wrinkles, if it is too hot you will get frosty undersized bullets with flashing spots at the vents and seams. If the mold is too hot or cold you will have problems with fill out and cutting sprues. Molds have a temperature sweet spot where they cast perfectly, this can be hard to find and hard to maintain. Brand new molds are notorious for being hard to cast with for the first couple sessions.
I am not saying this to discourage you, I just wanted to point out that with the hotplate method you may have temp swings that will make you pull your hair out.
A dedicated lead melter is set up to maintain a consistent temperature and that makes staying in the sweet spot easier.
DD

 

[jmorris]

The heat source for the casting machine I built is a 3500 watt replacement element for my oven. I wrapped it around the (3/8” thick) steel pipe I use for a pot and then wrapped a piece of stainless around that to hold the element tight against the pot. You can see the end of it coming out above the stainless holder, on the right side of the pot, in this video.



I control it with a PID and solid state relay and it will hold over 60 lbs full.

 

[Show Me]

used olds and a hot plate is a good way to get discouraged. Who sells a good mold or an accurate rifle

 

[johnjohn]

A hot plate is great for preheating your molds. It may melt lead "well enough" but you loose a lot of heat enough to frustrate you because of how much it slows you down.

 

[doubleh]

The melting point of aluminum or copper is well above 750 degrees but the draw back is each is an excellent conductor of heat with copper having the higher melting point and also the higher heat transfer capability. Steel or cast iron will be much better at retaining heat. Something capable of producing more heat will mean lower melting times and the capability to cast in a well ventilated area. Of course with more heat available you can turn it down to what is needed to get good wrinkle free bullets. I started with a little single burner Coleman gas camp stove and a dipper but graduated to a Lee electric pot. I cheat and use either a propane torch or my A/O rig to speed up the melt time holding the ingots just above the pot with channel lock pliers. The A/O torch makes lead run like water. My Lee pot's setting aren't the most accurate but I have determined by trial and error that it gives good results set at 750 degrees. Less and wrinkles appear. I lay Lee molds on the melt to heat, steel ones get helped with a propane torch.

 

[GeoDudeFlorida]

Melting casting alloys on a hot plate in a cast iron pot must be one of those old-school things that only worked during the upside down dark ages before Algore invented the internet - the same as drinking out of water hoses and running around in the grass with bare feet.
It’s remarkable my generation survived childhood!

 

[AJC1]

The melting point of aluminum or copper is well above 750 degrees but the draw back is each is an excellent conductor of heat with copper having the higher melting point and also the higher heat transfer capability. Steel or cast iron will be much better at retaining heat. Something capable of producing more heat will mean lower melting times and the capability to cast in a well ventilated area. Of course with more heat available you can turn it down to what is needed to get good wrinkle free bullets. I started with a little single burner Coleman gas camp stove and a dipper but graduated to a Lee electric pot. I cheat and use either a propane torch or my A/O rig to speed up the melt time holding the ingots just above the pot with channel lock pliers. The A/O torch makes lead run like water. My Lee pot's setting aren't the most accurate but I have determined by trial and error that it gives good results set at 750 degrees. Less and wrinkles appear. I lay Lee molds on the melt to heat, steel ones get helped with a propane torch.

I've never had a mold of any size or material that did not heat on the pot. A 4 hole or larger steel gang mold probably does but I haven't used one. The amount of material in a brass mold would make it warm the slowest, but in 30 ish minutes the pot and mold are ready to go.

 

[Shooterbob]

I’m not supposed to drink from a garden hose? When did that happen?

 

[doubleh]

I've never had a mold of any size or material that did not heat on the pot. A 4 hole or larger steel gang mold probably does but I haven't used one. The amount of material in a brass mold would make it warm the slowest, but in 30 ish minutes the pot and mold are ready to go.

I couldn't hold a 4 hole steel mold up long enough now to get anything done. With my method of helping the melt an mold heating I am casting quicker than 30 minutes. Casting is just work so I can shoot more and I like to get it done and over with as quickly as possible.