View Full Version : Any input on an electric furnace?

Jeremy Griffith
01-30-2012, 08:53 AM
So here is my predicament- I want to get an electric furnace around 180# to #220. I am very comfortable building a gas furnace and have build and rebuilt several kilns,glory holes, etc.. I am the current technician at RIT and have been so for the past 5 years and have been working on and building my own equipment for the past 8 or 9 years. That being said I know little to nothing about electric furnaces.
I can't have a gas furnace nor do I want one where my shop is now so here is where I stand. I have been talking with Eddie at Wet Dog a bit about building a furnace and he has suggested going with Silicon Carbide over MolyD because of the upfront cost...oh yeah I don't have a ton of money to spend. Although he says that would mean using a square liner rather than a pot and I really am not a fan of square tanks.

I have 240v, 3phase available and plenty of amps because I am located in an old factory. Any suggestions or help would be greatly appreciated.


Jeremy Griffith

Josh Bernbaum
01-30-2012, 09:11 AM
I've seen a home-built si-C furnace that has a replaceable, freestanding pot.
I'll give you his info if you're interested...

Jeremy Griffith
01-30-2012, 11:56 AM
Thanks Josh.

Yes please send me the info. PM me here or email me me@delishglass.com

Maybe I should just go with a Moly...any thoughts? Any ideas on the cost of having the control panel build with the elements? I would love to have someone sell me their plans and the controls. I could do the insulation and the steel work myself if I had something to work off of.

Pete VanderLaan
01-30-2012, 01:42 PM
I charge $1750.00 to build the moly panel. That's my labor. You would be paying extra for a large relay, an SCR, two controllers, a small interior breaker box, some ice cube relays, The actual panel box, a cooling fan, some switches, some #2 THHN cable, a bunch of conduit connectors, misc 14 gauge wire, and some odds and ends.

You would still need to buy the transformer and the elements which I also handle. It ain't cheap. I can get pretty specific on a quote depending on the actual furnace size. Size matters.

They are really nice... NY has some tax incentives to go with this sort of setup.

Jeremy Griffith
01-31-2012, 03:11 PM
Thanks Pete. I will definitely consider taking you up on this if my budget allows.

Pete VanderLaan
01-31-2012, 04:27 PM
Moly is just expensive,no matter how you do it. Once you have it it is really really nice.

Charles Friedman
01-31-2012, 06:01 PM

Try this.

I have one similar going since 1993. Just changed bars after 5 years and a new free standing pot after 3 or so years.

Electric panel isn't that hard to learn.

Yes, you can put a round pot into a square hole,
it works just fine,
thank you very much.

Dave Bross
02-01-2012, 04:51 PM
I've seen Charles' furnace...Sweet! Square is easier to build too.

Mark gave me a lot of help when I was building my first wire melter. Good guy.
His stuff is very good but you have to remember he melts all cullet so you would want to change some things for batch melts.

The main thing being venting for moisture and batch offgassing. Moisture can kill SC bars quickly...right Sky?

Lawrence Ruskin
02-02-2012, 09:50 AM
Just switch to cullet.

I have never used batch in my furnaces, although I have worked with it. One of the reasons is, I went over to this studio that used to be on 2ed, near where I worked on Granville Island. and here was the studio owner filling paper bags with batch. She was surround by dust. That dust has silica and chemicals in it that you don't want to breathe.

Then she would chuck these bags in her gas furnace; same thing, a face full of dust.

Then you're working is a studio full of dust, at least for a while. She was the one that was rolling up glass powder without some form of fan. She and her boyfriend at the time told me they were told at Sheridan collage (sp) in Ontario that these practices weren't dangerous.

Well yes, they are.

As well cullet you can store in a damp climate, and if you wash it there is no dust...

Be careful folks, you will get old some day and you don't want to die suffering from cancer or gasping for breath because of silicosis.

Pete VanderLaan
02-02-2012, 11:58 AM
If people had decent ventilation systems in the first place this stuff would not be an issue Lawrence. The cullets made in the NW all gas off to some degree, the 96 nuggets being the most prevalent.

You aren't in a trade which can be made entirely safe- period.
Glassworkers are dying from Alcohol and Tobacco products for the most part.
That being said, the collegiate structure in glass is sadly under informed and they like it that way.

Jeremy Griffith
02-02-2012, 02:25 PM
Does anyone know what the white and green crystals are that gas off of the 96 nuggets? I have found that if we charge slowly around 1960 degrees and then ramp up to 2100 degrees when we are ready to use the furnace it really cuts down on all the build up of "alien goobers" that clog the flue and build up around the door.

Pete I fully agree with you about the the lack of safety that is taught within colleges today. As a technician working daily with the students I make safety and ergonomics my top priority anytime I teach.

I heard an instructor at one point telling a class of 20 students that silica can't be dangerous because silica is sand and if it were deadly then everyone living near the sand would be dead. I about lost it.

Pete VanderLaan
02-02-2012, 03:24 PM
well, look at it this way, of all of the people living by the beach in 1865, not one is alive today!

It's boron. The nuggets are not completely melted which was a big difference between them and SP87 cullet. They attack virtually all silicates and fireclays, including alumina based stuff. It includes the crucible as well. There is no free lunch in easy melt land. The path to easy melting is to lower viscosity which can be done with either borax or lithium. Lithium costs a boatload more than borax.

Instruction is being diluted to a dangerous level.

Rick Sherbert
02-02-2012, 05:18 PM
I've always built gas furnaces. Just finished my first moly. It's not hard. The mystery is in the electronics and yes, it's not cheap. BUT, I use to have a 3k a month gas bill. My first full month electric was $730. That's annealer, lights, fan, furnace. It's more up front but it's safer, easier and longer lasting(I'm told) I bought the electronics used, bought the castings from Pete ( you could do your own) and I think I spent under 8K.


Pete VanderLaan
02-02-2012, 05:46 PM
well, yes you spent 8K but you didn't mention that you got an incredible deal on a used system that had hardly been touched. Wasn't it around 3K? If I add up the basic components for an electrical panel, transformer elements and cable, It's right around 10K for that without considering assembly. It is true that you can make your own castings but I don't think you'll save any money doing it. It just has a high front end cost. And Charles is right about being able to make your own panel although his is SiC which is not as demanding. It reminds me of this guy who was once watching me blow glass and as I worked he got more and more agitated. By the time I finished he was absolutely fulminating and I showed him the piece. He exploded and said "I could do that if I only knew how", and stormed off. I couldn't agree more. .

Got any diamond pads by the way?

Art Ciccotti
02-03-2012, 03:37 PM
Hi Jeremy,
About 4 seasons ago I built a SiC furnace using Mark Luckner's design. The pot is ~140lbs. Ive have had good luck with the unit. Although I did not use the controller he orginally suggested in his video. I called Holly at Denver machinery and ordered parts to a very simple controller which she gave me a schematic for. The interior is square but the pot fits in and out of the door opening just find with the removal of a few bricks. It (the pot) is not invested as Marked designed. I made a few other changes. I would be glad to talk to you over the phone and explain them it would take less time than typing. My # is 515 231 1267.