Smelting pot...threads on 20lb propane tank?

[SeabeeMan]

I'm getting one of BigBlack's smelter valves and am trying to figure out what to put it in. My thought is a typical cut-in-half 20lb propane tank, but rather than using the bottom, use the top. I could take the smelting valve, have it threaded or weld it to a threaded adapter, and then put it right in the bottom (was the top) of the tank, allowing me to get every last bit of lead. I cannot find what kind of threads are in the top of a 20lb tank. Not the POL/valve assembly, but the threads that are part of the tank that the assembly screws in to.

[fishhawk]

3/4 pipe thread

[bstone5]

The valves on the propane tank are screwed in very tight.

I make a water tank for cooling on the milling machine and lathe.

To get the valve out I had to weld the tank to my welding table at the base of the tank remove the guard ring at the top and use a big wrench with a cheater pipe to unscrew the valves from the tank.

Who ever installs the valves puts them in there very tight.

[SeabeeMan]

Good to know. I'm thinking this might work. I'll post pics of my build and hopefully I'll end up with something along the lines of a Satan's Little Smelter for a fraction of the cost.

[justingrosche]

Rich, based on past experience with bottom pour pots, you really don't want to get every last bit out. You'd be digging dross out of what ever type of nozzle you are using. If you didn't get every bit out, you'd likely call your pot the "Leak Master 1000" It wouldn't hurt to leave 5# a pot that will likely hold a hundred and a half. Even switching grades of alloy, you would never see an appreciatable difference to your final product.

[bstone5]

Drawing of a tank I thought about building.

I never built the pot but follows your concept.

The valve looks the same.

[SeabeeMan]

Good point on leaving some in there. I think I would just use this for the initial bulk cleanup and go back to my dutch oven for mixing alloys outside of the casting pot.

Bstone5, thats pretty much it. I want to avoid welding that nice valve in if at all possible in case I change my mind in the future. I figure if the outlet of the valve goes to a piece of angle iron, that should keep the whole contraption nicely in the flame and from freezing up.

I think I'll just weld on 4 legs of angle iron that put the chute just above the burner, as well as tack on a sheet metal windscreen around the legs to keep the heat on the pot.

[Dragonheart]

I considered using the top, but since I wanted a bottom pour a hole in the center would be in the way. I copied the RCBS pour design. Additionally, I found adding a skirt around the pot traps the heat, speeds up the melting and makes the pot very stable. My pot easily holds 200+ pounds and makes quick work of range lead.
Attachment 142460

[bstone5]

Three legs might be better, four legs might make the pot wobble if not on a level surface.
The valve like on a RCBS pot looks good and keeps the machined parts off the bottom and out of the lead.
There are a lot of ways to build the pot with a little welding.

[alamogunr]

The valves on the propane tank are screwed in very tight.

I make a water tank for cooling on the milling machine and lathe.

To get the valve out I had to weld the tank to my welding table at the base of the tank remove the guard ring at the top and use a big wrench with a cheater pipe to unscrew the valves from the tank.

Who ever installs the valves puts them in there very tight.

Several years ago I had a couple of propane tanks with the old valves. A friend owns a fuel company(propane, gasoline, etc.) so I asked about replacing the valve. They had a clamping arrangement for the tank and a huge pipe wrench. Piece of cake. The clamp was a metal strap arrangement with possibly a rubber lining. The tank didn't slip when they put the twist on the valve. I'm still using the tanks with the new valves.

[GrayTech]

A drain hole at the lowest point will clog with gunk often. Better to have a flat bottom pot if using bottom pour.

[GunStuff]

Have you never noticed that lead is much heavier than "gunk"? How does it clog the valve if you always leave a layer of lead at the bottom at the end of a casting session?

[Mal Paso]

Have you never noticed that lead is much heavier than "gunk"? How does it clog the valve if you always leave a layer of lead at the bottom at the end of a casting session?

Surface tension can hold an amazing amount crud on the bottom of the pot.

[SeabeeMan]

Would I be better off scrapping the top of a propane tank idea and just building myself a pot? It would be easy enough to cut a tank apart so there are just the straight sides and weld a piece of plate onto the bottom, or just make it square. Round seems to be easier to flux and scrape the edges, but I don't have a way to make a hoop other than cutting something apart.

[RogerDat]

Steel pipe gives you something to use for the round sides, weld a plate to the bottom drilled out for your valve. I know at least one member posted pictures of his built like this. Needed it for smelting sailboat keels by lowering them into a really big pot from a hoist. Heavy but solid build.

[Mal Paso]

Melting range scrap or any scrap lead always leaves some crud on the bottom. I think if the valve were 1/4" off the bottom or extended 1/4" into the bottom that would eliminate most of it. It's surface tension that holds it there and with lead on top it doesn't move much. If you want a round bottom weld a 3/4" coupling more toward the edge so it isn't the very bottom.

I buy my steel from a metal fabrication shop. I have had them roll 12ga steel into a 10" cylinder when I needed a custom size tube, that's a lot heavier than a propane tank. Off cuts from well casing is another idea.

[SeabeeMan]

Time to put my picture posting skills to the test.

I finished building my pot tonight with BigBlack's valve, a 20lb tank, and a whole bunch of advice from this wonderful forum. The goal was to build a bottom pour smelting pot and keep the cost to a minimum. I inherited my dad's habits of saving anything that could ever possibly be of use, which includes pulling anything made out of tube, angle or sheet steel apart before recycling/throwing away the rest of it. I managed to build the entire thing out of metal I had under the bench...and it looks like it. I also had to build this between a 4 year old sticking her head into the garage while I was trying to weld, a 6 month old needing naps, and my wife trying to sneak in some hours for work. Tack welding 22ga for the windscreen with a flux core welder is also not the easiest thing in the world, so those aren't the best welds in the world. Here we go!

Started with a 20lb tank I got for free from a supplier when I refilled 2 other tanks. The valve was already out and I left it filled with water for about a week. I cut it in half about 3 inches *below* the weld...remember that this is upside down. I started it with an air cutoff wheel but switched to the sawzall. It was tough to keep a straight line and you can see I got a little off at the end. My plan for the bottom half means it doesn't really matter how straight the cut is, but I'm not happy with that little cut. Next time I'll use the plasma cutter but I was a bit nervous about plasma and propane despite it being filled with water.

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Then came the valve. Tacked in place and welded in. I swapped out the small nipple BigBlack had in there for a 6" nipple, a 45" elbow, and then the original to get a downward angle on the spout and to get it away from the pot.

The original plan involved having BigBlack turn the valve down a bit and threading it for 1/2" NPT, which would then be installed using a 1/2"-3/4" bushing in the original threads. We had a few issues making that work out and eventually I just ended up with a valve to weld in. It looks like it is going to work great and I love how he took material off the shank of the bolt to allow better flow. I also ground the outer edge of the bolt, above the mating surface) so that there would be better flow between the outer edge of the head and inner edge of the tank threads.

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Originally I was just going to leave it open, but I took some knowledge from the stories of tinsel faires and live 22 rounds in smelting pots and figured that the bottom of the tank would make a great lid. I took some inspiration from another member, who I cannot remember and cannot find at this point, and made a hinge for the bottom of the pot from 1/2" black pipe elbows, nipples, and a tee. Now the bottom will act as a lid, allowing it to warm up faster and keeping things under control should some water get below the surface of the lead. I don't know if I'll need to add a hole or two to vent fumes but that is easy later.

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It needs legs. I figured out an angle that would allow the legs to sit nicely on the bottom curve and still end up wide enough for some stability. They are 3/16" walled 1 1/2" square tube that I got from a gang reel mower that somebody gave me. The mower sucked, but there was 30' of good tubing in the frame!

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With a little more planning I could have ended up with all the feet sticking out, but I wasn't going to cut up more material. The feet actually work really well the add stability and will keep it from sinking into my gravel driveway when I'm working with it.

Now to control the valve. I had some 5/15" hex stock left over from who knows what.

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[SeabeeMan]

Another random piece of metal...this one from an elliptical, I think...and an extra nut driver laying around make a nice wrench that can be removed to close the lid. Here you can see how far the spout gets the lead out from the pot.

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I thought about building this to sit over my fryer but then realized that my burner is only held on with one nut. Some cross bracing on the legs and a hole in just the right spot makes the burner an integral part of this pot. I can remove it to put it back on the fryer when needed, or I'll just but a different one.

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And last but not least, a windscreen. I had a few sheets of 12x18 22ga steel around, again from who knows what, so they were pressed into service. Remember, flux core welder on thin metal...not easy. I still need to clean things up so there is residue from the flux core wire everywhere.

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And the complete finished product, minus some brushing and grinding.

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Not bad for starting with a rusty propane tank and nothing but scrap metal. I'm hoping to get some pure lead I have in blocks and sheets melted down this weekend so I'll report back. I figure a cinder block or paver under the spout should work nicely to get the molds up to the right level. I'm slightly concerned that the spout is to close to the windscreen to get the middle row of my mini muffin tins, but another pipe nipple would fix that.

[Mytmousemalibu]

I need to build be a good smelter for the raw scrap I have! Well done! You might need some venting in the upper portion of the windscreen to keep a vertical pattern of heat and exhaust moving so your burner won't flame out.

[Wayne Smith]

Yes, you will need vent holes in the top. You are heating lead and air and the air expands, gotta go somewhere.