Can you use a AC/DC arc welder to create a smelting furnace?
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  1. #1
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    Can you use a AC/DC arc welder to create a smelting furnace?

    I was wondering if you could hook up ceramic heating elements to the leads. The ceramic elements would be enclosed in a crucible containing firebricks. I would then wait for it to heat up and poor aluminium in it. What do ya think ? I wonder what would be better, ac or dc through the heater. Probably dc as ac is only 1/sqrt 2 as powerful due to sine waves.
    Last edited by n00b; 05-16-2018 at 09:55 PM.
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  2. #2
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    I think that it would work but watch the duty cycle of your welder, most of them aren't made for 100% duty. You might want to get a copy of Dave Gingerly's (sp?) book on casting aluminium and read it. I wouldn't bother with heating elements just make an arc furnace.

  3. #3
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Are those ceramic heating elements designed to operate at the relatively
    low voltage at the welder output?

    It would be nice to have an electric forge, rather than f)%ting around with
    charcoal and a blow dryer.
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  4. #4
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Check out www.homemadetools.net. There are a several electric furnaces listed, but all use mains power just as you would with an electric kiln. No welder needed.

  5. #5
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Quote Originally Posted by n00b View Post
    I was wondering if you could hook up ceramic heating elements to the leads. The ceramic elements would be enclosed in a crucible containing firebricks. I would then wait for it to heat up and poor aluminium in it. What do ya think ? I wonder what would be better, ac or dc through the heater. Probably dc as ac is only 1/sqrt 2 as powerful due to sine waves.
    While not an electrical guru myself I have worked with some one who is on several projects building contollers for those ceramic heating elements that get used for stress relieving pipe welds. All the stress relieving I've been around that uses those ceramic heating elements has been done in places where there's also plenty of heavy duty welding machines around and I have never seen one of them used as a power source. Not even with the addition of a "controller" to regulate the welding machines out put. There's always a separate power source / controller to run those ceramic heating elements. I'm not saying you couldn't get a welding machine to power those heating elements just that it wouldn't be as simple as hooking the leads from the machine to the heating element. I'd be leery of trying it though for fear of doing major damage to the welding machine.

  6. #6
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    If any one would know about the feasibility of using a welding machine to power those ceramic heating elements it would be the folks at HotFoil. You could call their tech support, tell them what you're thinking about doing and see what they have to say about it. They'd also be a good source to buy those ceramic heating elements from.

    https://www.hotfoilehs.com/

  7. #7
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Quote Originally Posted by jpump5 View Post
    Are those ceramic heating elements designed to operate at the relatively
    low voltage at the welder output?

    It would be nice to have an electric forge, rather than f)%ting around with
    charcoal and a blow dryer.
    The lowest voltage I've seen those ceramic heating elements run with is 120 V. The last electric heat treating oven build project I worked on used 480 V to run them. All the power source / controllers I've helped with building all take AC power and convert it to DC for feeding to the elements.

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  8. #8
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Not all those ceramic heating elements you see have the same temperature reaching capacity. While they all pretty much use the same pink ceramic insulators the critical part is the type of alloy wire in them. A company called Kanthal specializes in providing these heating element alloys. Their website lists which alloys are suitable for different sustained temperatures.

    The other important thing about these heating elements is there length. You just can't hook up any random length you want. The resistance of the element (based on it's length) has to be matched to the power supply.

    https://www.kanthal.com/en/products/...ist-of-alloys/

  9. #9
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    easier to just use 120 or 240 volt AC but make sure shell of furnace is grounded if wire touches metal furnace shell and you touch you will get electrocuted. hurts bad. if shell is grounded and wire touches shell it will go to ground and blow the fuse
    .
    just my personal experience make sure its grounded

  10. #10
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Quote Originally Posted by FlaJoe View Post
    I think that it would work but watch the duty cycle of your welder, most of them aren't made for 100% duty. You might want to get a copy of Dave Gingerly's (sp?) book on casting aluminium and read it. I wouldn't bother with heating elements just make an arc furnace.
    Thanks. Yeah an arc furnace would be better. But I wonder what the pro/con of heating element vs carbon arc rods are. Steel's melt pt is 2500f and supposedly the best resistance coils can reach 2600f so i am in luck.
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  11. #11
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Here is the kiln in progress. I will upload pics later. I removed an extremely large terracotta pot from my pineapple plant. I then went in my scrap bin and got some cutoff's of 1" tube. I positioned the tubing at the bottom of the pot at 120* angles, forming a tripod. I layed down some wire mesh to act as reinforcement. Be sure to cover the pot hole with plate steel and lots of duct tape so it doesn't leak, i didn't add the duct tape so it leaked and made a mess. Then you take a medium sized beach bucket and center it on the tripod. Fill the breach bucket with crap like bricks to weight it down.

    Then mix about 2.5 gallons of mud. The mud is about 35% plaster paris, 35% sand, and 30% water (by volume not mass). Then pour the mud in the terracotta to the top. Wait about 1 day for the mud to cure and now you have a furnace shell with insulation. Then add wire or a torch or whatever and your furnace is done.
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  12. #12
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Quote Originally Posted by n00b View Post
    Thanks. Yeah an arc furnace would be better. But I wonder what the pro/con of heating element vs carbon arc rods are. Steel's melt pt is 2500f and supposedly the best resistance coils can reach 2600f so i am in luck.
    With carbon arc you'll generate RF, Ozone and intense UV light.
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  13. #13
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Quote Originally Posted by n00b View Post
    Thanks. Yeah an arc furnace would be better. But I wonder what the pro/con of heating element vs carbon arc rods are. Steel's melt pt is 2500f and supposedly the best resistance coils can reach 2600f so i am in luck.
    I hate to be the guy that p!sses all over your big idea but I just don't for see this going any where good. And by good I mean ending up with some thing that's at least half way useable.

    On the up side though I think you're about to get some lessons on what not to do you can apply to your second attempt at building one.

  14. #14
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Quote Originally Posted by n00b View Post
    Here is the kiln in progress. I will upload pics later. I removed an extremely large terracotta pot from my pineapple plant. I then went in my scrap bin and got some cutoff's of 1" tube. I positioned the tubing at the bottom of the pot at 120* angles, forming a tripod. I layed down some wire mesh to act as reinforcement. Be sure to cover the pot hole with plate steel and lots of duct tape so it doesn't leak, i didn't add the duct tape so it leaked and made a mess. Then you take a medium sized beach bucket and center it on the tripod. Fill the breach bucket with crap like bricks to weight it down.

    Then mix about 2.5 gallons of mud. The mud is about 35% plaster paris, 35% sand, and 30% water (by volume not mass). Then pour the mud in the terracotta to the top. Wait about 1 day for the mud to cure and now you have a furnace shell with insulation. Then add wire or a torch or whatever and your furnace is done.
    I just can't see that mix holding up to the kinds of temperatures your dreaming about achieving. I recommend you do some more research into "DIY home made refractory". Here's one to get you started.

    http://www.imarketingcenter.com/refractory.html

  15. #15
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    Re: Can you use a AC/DC arc welder to create a smelting furnace?

    Unless you live in a remote area of the Pacific like i do, you are better off using commercially available refractories like Mizzou, Castolite, etc than jacking around on your own. Propane foundries for melting aluminum are dead simple; I would not try to make a welder do something it wasn't made for.

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