how many watts needed for a melting pot?

[Tazza]

Are there any calculators out there that you can use to calculate what size heating element you need to melt a set amount of lead per hour?

I'm trying to work out how many heating bands i need to use to make a casting pot that will be dropping X amount of lead per hour. I need to do some guesstimation of how much i will be dropping per hour though.

I'm trying to build my own version of a bullet master, their website says it requires 3,700 odd watts, but i assume that would include the electric motor. It also has a pot that can hold 115 lbs of lead. The majority of projectiles i will be making will be 125-135 grains so hopefully i won't need the full 3,700 watts to do the job.

The plan is to keep the top of the pot covered too, hopefully it will keep in as much heat as possible.

[bbogue1]

Are there any calculators out there that you can use to calculate what size heating element you need to melt a set amount of lead per hour?

I'm trying to work out how many heating bands i need to use to make a casting pot that will be dropping X amount of lead per hour. I need to do some guesstimation of how much i will be dropping per hour though.

I'm trying to build my own version of a bullet master, their website says it requires 3,700 odd watts, but i assume that would include the electric motor. It also has a pot that can hold 115 lbs of lead. The majority of projectiles i will be making will be 125-135 grains so hopefully i won't need the full 3,700 watts to do the job.

The plan is to keep the top of the pot covered too, hopefully it will keep in as much heat as possible.

Here's a company that you can call who can answer your questions and a great article on how to determine your heating needs. go to http://thermo-llc.com/watt-density-w...it-mean-to-me/

[jsizemore]

I've got a Magma Cast Master Pot that uses 3-1000watt cartridge heaters. That thing melts lead right now!

[Tazza]

Thanks for the replies guys, hopefully the information i can get from thermo-llc can point me in the right direction. I was thinking i'd need around 3,000 watts, if i keep it covered as much as possible, it will help keep the heat in. Worst case, i can add another heating element and keep the power company happy

[CIC]

1.21 jigawatts!

[Tazza]

hehehe Is it sad that i get the reference?

Great movie(s) just looked up on IMDB, only 32 years old now

[CIC]

I'm glad you liked it.

[Idz]

lead melts at 650 F, lead specific heat = 0.03 BTU/(F*lb), lead latent heat = 9.65 BTU/lb, 1 KW*hr = 3412 BTU

so to take 1 lb of lead from 50F to 650F requires 0.03*(650-50)*1 = 18 BTU
to melt that lead requires 1*9.65 = 9.65 BTU
total energy per lb of lead melted = 18 + 9.65 = 27.65 BTU = 0.008 KW*hr

if your system was perfectly insulated it doesn't require much energy to melt lead.
When I melt range scrap with a propane system I get about 70% yield of lead and get a thermal efficiency of melted lead energy / propane energy of about 15%. The rest of energy is lost due to imperfect insulation, chimney losses, and heating the junk in the range scrap.

[Tazza]

That is exactly the information i'm after, thank you. From my very rough calculations with those figures, 2,400-3,000 watts will be enough. It just depends on how fast it can recover when "cold" lead is added to the pot. Ideally you want enough energy there to be able to keep the metal liquid as you add more that is still solid.

It's one of those things isn't it? you can never get 100% efficiency, with using gas to heat, you will loose even more as where you try and input the heat, you have no insulation from the outside air. I guess it's all the price you have to pay.

[dikman]

Given what's happening to electricity costs in this country I reckon you should factor in buying your own generator to power it! Probably work out cheaper in the long run!!

[Tazza]

Dikman - You are spot on there..... I try and reduce the power we use, yet the bills just keep going up. You use less KWH, they just change you more for "access" to the grid, it used to be 50c a day when we bought our house 4 years ago, now what, $1.20 per day? no matter how much energy you use. Now they charge you for the power meters too!.

Of you are in SA, yours is even worse, i heard yours is the most expensive in oz. AND it goes down when they have storms.

[Ausglock]

Tazza.
There is a mob in Coffs called TEE.
They do all this sort of stuff.
Heating elements are their thing.
I use them for all my electric heating here at the Sawmill in Grafton.

[Tazza]

Thanks fr the lead Trevor, i know who to harass if the heating bands i have aren't up to the job.

The heating bands were gifted to me, hopefully they will do the job, but if not, i can always harass TEE to come up with an alternative. They may even have the insulation that i will need.

[dikman]

Just to set the record straight, we (in SA) have the most expensive electricity in the world! We also have, so we've been told, the most expensive building in the world - the new hospital, which is going to cost the taxpayer $1 million a day, for the next 30 years, to pay it off!

Pretty good, eh?

Tazza, take a few photos as you go, if it works out others may be interested.

[Ausglock]

Got our power bill yesterday. 28.47cents per KWH. Bloody Ned Kelly mongrels.
Thanks christ we have a 5KW solar setup to offset the power bill.
The solar feedin paid $192...

[Tazza]

I will be sure to take pictures, a member is going to take pictures of his mark 5 melting pot for me to get some sizes off to work from. I need some ideas of what size i needed to make it.

I didn't realize it was the most expensive in the world, yet i did know it was expensive and not as reliable as it should be. The cheap skates don't turn the "booster" generator for when you have high load and need more energy, when i heard that on the news i couldn't believe they would do that. You pay for a grid connection, they should provide you with non stop power.

Trevor, we have solar at home too, but we missed the 50c feed in tarrif by two bloody months, so we get a MASSIVE 6c/kw, which last bill went to 7c woohoo!

BUT

They put the power consumed as about 26c/kw PLUS GST, yet the 7c is Including, go figure hey? gotta make it sound bigger than it really is. Glad you have a good sized system to really help with your bills, I do try and run as many power hungry things during the day to let the sun power it.

[Idz]

Let's see 0.2847 A$ = 0.223 US$. Our rate here in New Mexico, USA is 0.1152 US$ / KW*hr are you guys paying a Carbon Tax to the global warming clowns?

[Tazza]

That is without a carbon tax.

The thing that really stinks is most of our generators are goal powered, we export millions of tonnes of coal every week, so surely we can get it cheap to make power.

The big charge we get that you may not have is a connection fee or line fee. We have to pay about $1.15 per day to have access to the grid to use when we need it. Four years ago, this charge was only $0.50 per day

[Tazza]

Just remembered i have a bill in my email from earlier this week.

Peek power (anytime use) $0.26961/kw
T33 controlled power (off-peek hot water) $0.22528/kw
Supply charge per day for peek power $1.25609/day
Supply charge for off-peek power $0.03c/day

All including taxes

[Idz]

The connection fee is 12 US$ / month so about 0.40 / day. I guess we're just behind the times over here in the USA. Fortunately for us we now have a President that got rid of the previous administration's War on Coal.