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Questions on Converting a University Surplus Furnace

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 A couple years ago I bought an electric furnace from a university's surplus auction. I believe something exploded inside the furnace as some of the silicon-carbide heating elements were in pieces and metal was strewn all over the inside of it. Anyway, I have no experience with this type of metal working, though I do weld and have experience with aluminum fabrication, but I would like to get into forging and learn about it. And so, I am trying to figure out how to convert it into a usable furnace. I'm not quite sure how to do that, so if anyone has any suggestions I would love to hear them. Should I try to keep it electric, or should I convert it to gas? Is the interior too big? Should I weld a stand to set it on its side? Is it even possible to use this as a furnace? I cant 

Attached are photos of the furnace, it measures almost 3 ft external diameter, its about 4 ft tall, has an inner diameter of ~15 inches and an inner height of 19 inches. The heating elements are silicon-carbide and reach down to the interior floor of the furnace. Not shown is a 12 inch tall circular metal grate that I guess was supposed to prevent people from touching the heating elements. I'm not sure what the red band is around it, there's nothing inside it.






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First: what do you want the furnace to do?  Melt Metal? Heat treat blades? Be a forge?

Is the current insulation hard or soft?

Would your location support a massive electrical draw for such a furnace?

Can you pay for  massive electric usage?

Need to know such things to make good suggestions.

Also you do realize that if you want a forge you could build a propane one that would work better and be cheaper to run?  Currently it's sort of like someone asking to convert a dump truck into a commuter vehicle.


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I would like it to be a forge. I’m not sure on the terminology but like hammering, anvils that sort of forge.

The current insulation is kind of a mixture, the floor of it is hard, the sides are soft, and there are several layers on the top. The innermost layer on the top is sort of a material similar to the feel of a ‘meringue’ cookie, and then the outer layer is like a softer fibrous material.

My location has single phase 120 and 240.

I would prefer to keep the costs low.


That makes sense, that’s kinda what I thought about this being a little overkill of a furnace. Could I convert this to run on propane? or is that something that wouldn’t be possible? Also, thanks for the response!


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Cost of running a gas forge is generally proportional to it's size and currently that is HUGE.    (Note that the information provided is not sufficient: do you have 220 3 phase at 100 amps? or is that 220 single phase at 30 amps?  I'm currently getting power to my shop and got the electrician to put in a 50 amp 220 plug so I could run either my triphammer or my welder and I will have 200 amp service just to my hobby shop!)

Usually when folks tell us they need a large forge it's because they want to make swords; not realizing that anytime you are heating up more steel than you can work at one go you are degrading it with decarburization, grain growth and scale losses.  A good sword forge needs to get about 6" hot at a time  Have a "back door" can allow a fairly small forge to do long work!.

Now people doing sculptural work may need large volume spaces and they pay for the privilege!

I built both my first two propane forges at gas forge building workshops put on at SOFA in Troy Ohio; about 20 years old now and still going strong with relines as needed---just replaced the burners on my NA one for the first time---went with Frosty T's.

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Welcome aboard bravoecho, glad to have you. Do you have a less cumbersome nick name, name, handle we can address you by? 

While you COULD rehab or convert that kiln it's not very practical for a forge, however you do it. Spend a little time looking through the propane forge section of Iforge and get an idea of what makes an effective forge. The solid fuel forge section covers coal, charcoal, even corn burning forges. 

I'm with Steve sell it hopefully for more than you paid and put that into buying or making a useful forge. We'll be more than happy to help. Heck, there may be a forum member living within visiting distance who'll come over and give you a hand directly. 

Just don't get in a hurry, it's better to take a little time and get a practical forge. Do NOT try for the perfect forge that will last you for years, It's blacksmithing, perfection is an overinflated opinion, not reality. Don't rush into anything, the only thing rushing is likely to do is make your mistake permanent more quickly.

Frosty The Lucky.

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14 hours ago, SLAG said:

Is the "softer fibrous material" asbestos?

Not sure how to tell, you can see it pretty well in some of my photos-its the yellow-ish stuff. Is there an easy way to determine if it is?

14 hours ago, JHCC said:

Welcome to IFI, by the way. Where are you in central Ohio?

Thanks! I'm midway between Urbana and Marysville, but I go to OSU so I'm back home for the summer.

14 hours ago, ThomasPowers said:

Note that the information provided is not sufficient: do you have 220 3 phase at 100 amps? or is that 220 single phase at 30 amps? 

I believe it is all single phase with 120 VAC and 240 VAC, there's two 240 outlets right now and one of them powers my Lincoln buzzbox. 


12 hours ago, Frosty said:

Welcome aboard bravoecho, glad to have you. Do you have a less cumbersome nick name, name, handle we can address you by? 

While you COULD rehab or convert that kiln it's not very practical for a forge

I'm with Steve sell it hopefully for more than you paid and put that into buying or making a useful forge.

Thanks for the welcome! My name is Ben, I guess I should probably change my username. I'll look through the forums a bit and find something, do you think I could reuse the insulation from this furnace? There is tons of it. I believe I paid about $70 for it and if I'm going to get somewhere around the same price reselling it I would rather forgo the hassle and just reuse the materials. Also, is there a certain style of forge that would be a sort of "jack-of-all-trades"? I want to keep my options open for what I could make.

Thanks everyone who has commented so far, I really appreciate the advice. It sounds like my best bet is to make a propane fueled forge.

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Your login name is just fine, If you just sign your posts for a while we'll start to ID you as Ben. We CAN learn, if it's in front of us long enough.;) No need to quote everything it basically just takes up bandwidth for no good reason. Lots of members live where broad band doesn't exist and pay for access on dialup connections. So, use the quote sparingly say if there is something you wish to comment or question specifically in a large text. So far nothing you've quoted counts as needing it. Yes? 

Don't sweat it, there's a learning curve and it changes every now and then so we all get to learn the "new" way something's done. We'll coach you.

There's no telling if you can reuse pieces of that old kiln to build a successful forge and if you start taking it apart it turns from a possibly sellable piece of equipment to a dump run. Do a little shopping around online and see what people are asking for similar kilns, I'm betting asking prices are WAY higher than $70. Selling prices are different of course, usually quite a bit lower but sometimes you get what you're asking for.

You're looking at a whole LOT more work and hassle trying to save a couple bucks salvaging most anything from that. Maybe if you were building an electric heat treat oven the controls might be worth salvaging, maybe the heat elements but . . . 

A propane forge is easy to make in its simplest form and with a little imagination is as flexible as a boy could want. Summer before last our club held a forge and burner workshop. We built basic, bolt together, brick pile forges and 1/2" T burners. The cost to members was around $120 but that included: "Morgan ceramics K-26 insulating fire bricks", angle iron, all thread, bolts, nuts, washers, Plistex 900 kiln wash and the burner from the regulator/hose to everything necessary to make a 1/2" T burner.

Most of the guys who built one did so just to get started but several are making good money making: knives, axes, tools, yard art, etc. in a forge of about 150 cu/in volume. Welding damascus billets as well.

Pic below is of one at the workshop, maybe 5 minutes after being lit.

Frosty The Lucky.



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"One forge to do everything?"  pretty much describes a solid fuel forge.     Propane forges are generally constrained by their size.  You can build clamshell forges that give you more options in 2D  but 3D will always be an issue.  However most folks will find that a forge that does 80% of what they want is fairly easy to design.  It's that other 20% that can make things expensive to build or run and may actually do better using a rosebud on a torch.

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  • 2 weeks later...

Thanks for the tips! 

I go to the university that I bought it from so I am asking around to see if anyone recognizes it and can tell me what it's made from. I just bought some parts to make two T-burners as I think propane is a more suitable choice regardless. That box furnace looks really good, I believe I have all of the materials in my workshop! :D. In the middle of writing this reply I took the white insulation floor out of the kiln/furnace and there are bricks underneath, would these be usable? They are 4.5x3x9 inches and light brown in color, there are appx nine bricks. 


Frosty, I see your point about how it would be barely helpful to reuse the materials however I have my doubts regarding the viability of selling it. There are no controls/electronics associated with it and I've found out the heating elements are sort obscure and there is no information on them. In addition, part of the more solid insulation on the top is cracked, and it weighs several hundred pounds. 

I just measured the sides and its 8 inches thick of what I am assuming to be ceramic wool.

Another question that I couldn't find searching: should I buy tongs or should I weld up a pair?

Also, thanks for the help so far! Everyone is much nicer than some of the forums I have tried to join.


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Thank you for the kind words.  The site is set up to be helpful as we want you to succeed.  Thank the moderators for keeping things running smoothly.

Figure out what you want to do and how large a forge or heat source you need for those projects.  Run the costs so you will have something to compare against.  

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"Another question that I couldn't find searching: should I buy tongs or should I weld up a pair?"

Yes definitely you should  buy tongs or weld up a pair!   If you are good at forging and that is how you want to spend your time---forge them.  If you are new to smithing but have welding equipment and skills (or don't want to make tongs)  weld them up of buy them or buy tong kits to split the difference in skill levels!

I have bought nearly all my tongs, I have made a set from lug wrenches and another from titanium; but tong making is not how I want to spend my time and I have bought dozens of pairs for under US$12.  I find billet welding a lot more fun that tong making!

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I was tickled pink with the bundle of Ken's tongs I bought in the beginning. I don't know why people think that tongs are a good beginner project. You can quickly progress to making tongs but it's not something I'd recommend for a first or second project. Have you seen the easy tong blueprint here? I thought I had the link on my clipboard but alas I don't. It's BP001 Easy to make tongs.

My advice when making your first set of real tongs is to do each operation on both pieces. Don't forge one side all the way through then start the other side. When I figured this out it improved my tong making by a sight. 


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  • 3 weeks later...

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