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borderline123
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Joined: 13 Sep 2008
Posts: 16
Location: Quebec, CANADA
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 Posted: Fri Oct 24, 2008 2:37 pm Post subject: oven made from what material? |
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Just tried to figure what are the material used to make the oven base and side. Should we use Drywall panel?
Thanks!
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TroyO
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Joined: 07 Nov 2005
Posts: 65
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| Posted: Fri Oct 24, 2008 4:24 pm Post subject: |
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Nope, not drywall!
Most folks are using a product called "Hardie Backer" that is commonly used as an underlayment material for tile.
It's off white in color, and usually comes in 3x5 sheets. It is very heavy as well. Most Home Depot/Lowes type places have it. (It also comes in 4x8 sheets... if you can lift it, LOL!)
The specific stuff is "Hardiebacker 500" which is 1/2 inch thick.
http://www.jameshardie.com/homeowner/backerboard.shtml
Folks use that because it is cheap and fairly fireproof. If is prone to cracking over time, though. (It will last a good while, but eventually may crack especially if you aren't prone to treating stuff gently. )
I'm re-doing an oven in stainless steel here soon, becuase my Hardiebacker one is falling apart. But, I've got the rest of it working pretty well so I know it's a good investment... I don't regret making the less expensive one first, it lasted 3 or so years. |
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cod
Master
Joined: 05 Nov 2006
Posts: 322
Location: San Francisco
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| Posted: Fri Oct 24, 2008 9:39 pm Post subject: |
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you can do an all metal oven. But I would advise not touching it, and making sure it's grounded properly. hardibacker provides grounding and heat insulation, but it can be fragile over time.
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ahillworks
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Joined: 18 Nov 2007
Posts: 308
Location: Orlando FL
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| Posted: Sat Oct 25, 2008 12:38 am Post subject: |
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| Use the HardiBaker Last thing you need is a fire or even a circuit to trip. |
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crashmann
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Joined: 27 Sep 2005
Posts: 501
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| Posted: Sat Oct 25, 2008 12:40 am Post subject: |
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Fragile?
Nahh, not at all!
Some folks travel around the world to see the Grand Canyon. Me, I just have to go to the garage :-p
The cracks formed where the mounting holes for the ceramic donuts were in a straight horizontal or vertical line. You should stagger your mounts to avoid these fractures.
Hardibacker 500 is a great way to build your first oven. If you don't bang on the oven to get the molds out of your pulled plastic, then it should run fine for several years. The reason the Hardibacker is recommended is because it contains calcium silicate which is a good electrical insulator and heat resistant material, as recommended in the Thurston James Molding and Casting book.
Be sure to wear a respirator when cutting the material since you don't want to end up with silicosis
Charlie |
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jegner
Site Admin
Joined: 30 May 2003
Posts: 2144
Location: Texas, USA
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| Posted: Sat Oct 25, 2008 7:34 am Post subject: |
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The Hardibacker 500 is a substitute for an industrial material called calcium silicate millbaord. McMaster Car has the stuff but at $300 a sheet, I had to find a substitute, so after talking with a chemical engineer, I learned the Hardibacker 500 was 60% calcium silicate and the majority of the remaining 40% was silica. Not a bad substitute!
Now, it will crack, but it you know this ahead of time, and double up the floor of the oven, [the only part that seems to crack on my machine] But DOES NOT seem to affect the performance.
Some oven floor support, and you should be good for a long while. I'm runing over 3 years on my current oven, and I have a crack, but still going!
Jim |
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cod
Master
Joined: 05 Nov 2006
Posts: 322
Location: San Francisco
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| Posted: Sat Oct 25, 2008 9:47 am Post subject: |
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| ahillworks wrote: | | Use the HardiBaker Last thing you need is a fire or even a circuit to trip. |
Hardibacker works, but I don't think its the best way to go.
If I did it over I probably would just go all-metal, maybe with an insulated(mineral wool) mid-space between inner and outer metal shells. Or I would just do single wall because I have lots of room.
If you look at any oven in the kitchen you will find this type of steel double-hull construction with insulation between. It's just more durable, and can be designed to contain heat and electricity effectively, and be safer.
As far as circuits tripping- I believe a properly grounded oven(3 prong wiring from panel to oven) with a grounded steel shell is much safer than an insulated, ungrounded shell. You actually WANT a circuit to trip. This is a safety mechanism. If you have a grounded steel shell, then the likelihood of stray voltages going thru you instead of to ground is reduced. Any short that hits the grounded shell will trip the breaker. This is desirable. If all you have is hardibacker and you as possible electric routes, then electricity will always choose you!
do a search for Harley guy's all-metal oven. Not sure what happened to him, maybe he retired. Not sure how well-grounded his oven was either, but it is an option.
disclaimer: I am not an electrician nor claim to be , but I believe this is how it works. Be careful with electricity.
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inventer
Novice
Joined: 22 Apr 2008
Posts: 55
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| Posted: Sun Oct 26, 2008 12:16 am Post subject: double ground |
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| Hi guys, mind my input ? As you know my oven is all metal, when I had an electrican over to go over how to hook up the 220 to my coils he expressed how important grounding is. Luckly theirs a ground rod outside for the house ground panel, so I also ran a ground from my unit to the ground rod outside and it was good I did, have tripped my breakers several times. At this point, I'm running 2-220 lines for the 4 thermostats and 4 coils for my small and large frames I have for small or large pulls. Just my 2 cents, been shocked several times over the years, I have the upmost respect for electric, be carefull and safe. Tony |
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CrazyFool
Expert
Joined: 07 May 2008
Posts: 203
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| Posted: Sun Oct 26, 2008 7:39 am Post subject: |
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Since my design was an over/under I was paranoid about any HardiBacker breaking loose and falling down on my platen. So I used self tapping sheet metal screws to screw the HardiBacker to the oven's wooden frame. But I also used a generous amount of mortar to 'glue' the HardiBacker to the wood. If a crack ever appears I plan to fill it with mortar. No biggie.
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borderline123
Newbie
Joined: 13 Sep 2008
Posts: 16
Location: Quebec, CANADA
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| Posted: Mon Oct 27, 2008 3:21 pm Post subject: |
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Hey thanks everyone for your inputs! 
Hardie Baker seems a good idea (didn't knew it could crack!) but I will probably make it from steel finally. It will be more easy for me to work with that as I'm working in a steel shop. I also found used ceramic holder (was for home dryer) 80 count for 10$ 
But I will make sure to have a good grounded system! ungrounded things can be hazardous!!
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thebluecanary
Expert
Joined: 02 Feb 2006
Posts: 123
Location: St. Louis, MO
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| Posted: Mon Dec 29, 2008 9:26 am Post subject: |
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| CrazyFool wrote: | Since my design was an over/under I was paranoid about any HardiBacker breaking loose and falling down on my platen. So I used self tapping sheet metal screws to screw the HardiBacker to the oven's wooden frame. But I also used a generous amount of mortar to 'glue' the HardiBacker to the wood. If a crack ever appears I plan to fill it with mortar. No biggie.
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I like that idea. I have about half a bucket of that stuff left over from tiling my kitchen. I might have a good uses for it now! |
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