My home made mold heater

[Paul_R]

I built this nifty oven to warm my molds in. Made from 3/8" and 1/2" aluminum with a solid aluminum block base that drops into my spare Lee 4-20. Probably overkill but it works great! About $20 worth of materials and hardware.

http://i67.photobucket.com/albums/h312/pjriss/20150927_115728.jpg
http://i67.photobucket.com/albums/h312/pjriss/20150927_115718.jpg
http://i67.photobucket.com/albums/h312/pjriss/20150927_115903.jpg

[VHoward]

You shouldn't run a melting pot without lead in it. Tends to burn out the element and liner faster than normal. Most just use a $10 hot plate to warm their molds on. If you need a wind break, a metal coffee can over the mold will hold the heat from the hot plate in.

That should work as long as the pot lasts.

[Paul_R]

I figure the mass of block will soak up enough heat. So far so good

Edit: I could ball up a foil cover around the block so I have direct contact all around. Think I'll do that, thanks for the heads up!

[VHoward]

Or some sacrificial lead to put in the pot to take up the air space.

[bangerjim]

The high BTU concentration element used in lead pots really likes to have VERY intimate contact with lead! It disperses the heat away from the element rapidly. Free air space is not really good. That could cause severe life shortening of the element.

$10 will get you a great hot plate! Save your ~$60 Lee pot for more important things.

Nice machine shop metal work.

And remember you not just "warming up your mold". You are heating it to FULL CASTING TEMPERATURE! That way you get perfect drops form #1 when casting.


banger

[Paul_R]

$10 got me this used scaled up casting pot, I'll let ya know how long it lasts :mrgreen:

[JonB_in_Glencoe]

I wonder if sand would work...to fill the pot ?
I've read people using sand in a lead pot to anneal brass.

[Paul_R]

Funny you should mention sand, I bought this pot specifically to fill with sand and anneal cases. I use x-fine glass bead blasting media and it works great. Then in a fit of ale induced brilliance I came up with this mold oven idea. Never occurred to me that overheating would be a problem but it makes perfect sense. Getting anything in the little space there is turns out to be a problem, including sand. The foil sleeve fits surprisingly tight I think it'll work since I'm nowhere near full power just to warm molds.

[seawolf]

A flip down door notched for mold handles for a wind screen will help hold heat. pour in some glass beads then rotate the box a few times to bring the box down to the level desired. Should transfer heat well.

[NavyVet1959]

Well, I guess that's one way to stop a Lee pot from dripping... :)

I just use a hot plate with a 3/8" thick disc of aluminum sitting on top of it.

[Mike W1]

When it's all said and done the mould is being heated by a transfer from the bottom and not by the air surrounding the mould. I suppose having a enclosure might help a very little bit but really not worth the bother IMHO. I built one, modified it with insulation, and tossed it in the corner. The heater, hot plate in my case, furnace in this one, doesn't really give a dang if it's there or not. MAYBE, if you're casting outside in a tornado it might do some good!

[Paul_R]

When it's all said and done the mould is being heated by a transfer from the bottom and not by the air surrounding the mould. I suppose having a enclosure might help a very little bit but really not worth the bother IMHO. I built one, modified it with insulation, and tossed it in the corner. The heater, hot plate in my case, furnace in this one, doesn't really give a dang if it's there or not. MAYBE, if you're casting outside in a tornado it might do some good!

That tight little enclosure does help keep the mold secure and that's a good thing around a klutz like me. Imagine that, I can cast in a tornado! Who knew? :mrgreen:

[NavyVet1959]

Unless an enclosure is insulated, it's entirely possible that an enclosure like that could result in a lower temperature for the mold than just having the mold heated from the bottom on a similar wattage burner. The reason for this is that you might be adding more surface area for the surrounding air to transfer heat away from the enclosure, thus reducing the temperature inside the enclosure.

[montana_charlie]

Or some sacrificial lead to put in the pot to take up the air space.
Or zink ... if any has accumulated from sorting wheelweights.

[mongoose33]

Unless an enclosure is insulated, it's entirely possible that an enclosure like that could result in a lower temperature for the mold than just having the mold heated from the bottom on a similar wattage burner. The reason for this is that you might be adding more surface area for the surrounding air to transfer heat away from the enclosure, thus reducing the temperature inside the enclosure.

If the enclosure approached the temperature he wants for the mold, I'd think infrared heat from all around the mold would offset the loss due to convection.

That said, I'd put a door on it.

And I'd add a thermometer.

Here's my setup:

150197

I'd love to have one with the thick aluminum stock like the OP. And yes, I'd bag the lead pot for a hot plate.

[NavyVet1959]

If the enclosure approached the temperature he wants for the mold, I'd think infrared heat from all around the mold would offset the loss due to convection.

That said, I'd put a door on it.


I'm not saying that it won't work, I'm just saying that it is not necessarily as efficient from an energy input standpoint. But, then again, having a burner that is larger than the object being heated is also not efficient. Ideally, you want all the BTUs input into the device to go into heating the mold and not the surrounding air.

[Mike W1]

Now that I think about it something along these lines came up years ago on CB-L. Was making the warming shelves for my 10 lb. Lees and the consensus was keep em' small as possible because of the heat radiation loss. BTW I did and they really worked out fine for my Lyman DC moulds. Not so hot for a Lee though.

[Paul_R]

If the enclosure approached the temperature he wants for the mold, I'd think infrared heat from all around the mold would offset the loss due to convection.

That said, I'd put a door on it.

And I'd add a thermometer.

Here's my setup:

150197

I'd love to have one with the thick aluminum stock like the OP. And yes, I'd bag the lead pot for a hot plate.


I'm not sold on a door but I do have a thermometer

http://i67.photobucket.com/albums/h312/pjriss/20151002_102653.jpg


I appreciate all the input from everybody, thanks!

[mozeppa]

Or some sacrificial lead to put in the pot to take up the air space.

plus 1 !

[Mike W1]

I'm not sold on a door but I do have a thermometer

http://i67.photobucket.com/albums/h312/pjriss/20151002_102653.jpg


I appreciate all the input from everybody, thanks!

Didn't see that thing in the middle on your first picture. You monitoring air temp or base temp with that?

[Paul_R]

That's monitoring mold temp, which test's out to be within about 5 degrees of base temp. It's just a loose block of aluminum.

[Three44s]

Lead in the pot or not ..... nice job!

Your use of AL got me thinking about my lubrisizer mount that's steel but does not transmit heat as well as I'd like ......... but then my magnetic engine heaters won't stick to AL ...... so here I go again .......

It's always something ......

Best regards and thanks for sharing!

Three 44s