oven

[geeb57]

new here.
Trying to build a oven. 5'deep x 4'tall x 3'wide, have read most of the tips. just a couple Questions. The sides of my oven will be "outside" my shop (under roof but not enclosed) What type insulation can i use to keep heating efficiency? My oven walls are 10 gauge with a removable top, will have a window on both sides, 4 elements from a double oven. Does the oven need a vent of some kind? It wont be sealed completely,but you never know! What about lighting in the oven? Just want to coat bike frames ,blocks ,small parts. I figure i'll miss a few questions but you guys seem to have the answers! Anything else you can recommend would be nice!
Thanks

[DALE]

oven

Okay I'll chime in. Welcome aboard. First is the oven going to have a metal layer outside and inside with the insulation between.If so you can use home fiberglass rolled insulation just be sure to remove the paper backer or vapor barrior as some call it. Go with 4 inch min.Second why the window on 2 sides? Third if it's not sealed then you may skip the vent(some peolpe will cry about this but it will work fine).As long as it has a leak somewhere for expanding air to escape so it won't build pressure.If you find the fumes bother you (and it does bother some people) then install the vent.Four oven lights from a regular oven will work.Most hardware stores carry the bulbs for them.

[WAORacing]

Dale, will it matter where the heat elements are placed? Second, how big of an oven can you go with the 2 big and 2 small elements and still have good efficiency?

[customandsound]

Re: oven

Okay I'll chime in. Welcome aboard. First is the oven going to have a metal layer outside and inside with the insulation between.If so you can use home fiberglass rolled insulation just be sure to remove the paper backer or vapor barrior as some call it. Go with 4 inch min.Second why the window on 2 sides? Third if it's not sealed then you may skip the vent(some peolpe will cry about this but it will work fine).As long as it has a leak somewhere for expanding air to escape so it won't build pressure.If you find the fumes bother you (and it does bother some people) then install the vent.Four oven lights from a regular oven will work.Most hardware stores carry the bulbs for them.

just got to home depot and get r-13 unfaced... you don't want the kraft ..

[bzer1]

Sounds like an awsome oven...But why 10g steel? Seems a bit excessive. Most commercial ovens are 14g. If you are double walling it you might might want to sandwich mineral wool sheets between the inside wall and the outside wall. Mineral wool has great insulating properties and will keep your insulation very consistant, preventing hot and cool spots. It's also more fire resistant which will allow you greater heat capacity. Building it in a more modular fasion will also allow you to expand your oven a little easier. Good luck! Post some pics and keep us posted on your progress.

[geeb57]

thanks for the info!

The oven will have only the inner steel wall but i plan to enclose it with cinderblock. Insulation between the steel and the block should be sufficient,right? I have two windows from the double oven i'm using so i figured one on each side, so i could get a better view of the "flow out"?

A ceramic "keyless" light fixture should be good for the light i'm guessing just concerned about the heat and wires.

As for "why 10 ga?" the steel supply around here is not into thin material so we have to ..."run what ya brung" lol

One last question: how do you figure material? Is there a rule of thumb as to lb of powder to sq foot of coverage?

Thanks for your help

Pat

[senna-the-great]

Hi,
I'm also in the design stages of an oven about 3 by4 by 5 feet. I have a
line on panels from a walk in freezer ,there 18 gauge galv. on eachside with
a 4 inch foam insulated core and the snap together. My question for Dale
or whoever is what do you use for a fan? is it from a certain application?
Thanks,
Art

[tomg552001]

Wow you beginners (i figure you're beginners, if you're not i apologize ahead of time) are really going all out in the beginning lol. Good luck in building your ovens...we all benefit from these type of threads.

[bzer1]

Hey Art,

I'm not so sure that gavanized sheet would be your best choice. If I remember correctly, when heated to high temps it emits some pretty harmful vapors. I might be wrong about that, maybe someone else can confirm or deny. If I'm correct, then not only would it be harmful to you but it would also add some unwanted chemicals into your curing process. My understanding of oven building is somewhat limited but I think aluminzed sheet is ok. I'm not really sure about the thickness, but have seen, where some have used 14ga sheet. As far as a fan goes you could probably use a fan from any standard kitchen convection oven. I would also make sure to use some sort of baffle to make sure that you don't blow the powder off your work.

[tomg552001]

I'm pretty sure galvanized or aluminized sheeting will burn it's coating off after time. You might want to try galvalume, or galvanel....its sheet metal impregnated when in liquid form so there is no real coating to burn off. As you said, i think i do remember seeing something about harmful fumes from galvanized burning off.

[bzer1]

I knew if I looked long enough I would find something. Here it is for your reading pleasure.


Why don't you use galvanized steel?

In short, zinc oxide is bad for you.

Heating galvanized steel can result in an unpleasant condition called welder's fever. Caged animals can develop illness brought on by swallowing or licking galvanized parts. We've known many people in the metal working profession forced to take extended sabbaticals due to various kinds metals poisoning. We work intimately with our construction materials and avoid galvanized steel out of concern for both our own health and that of our customers.

Additionally, the zinc coating on galvanized steel, used as a rust deterrent, is by no means permanent. The coating will often corrode into white rust which then results corrosion of the steel underneath. Due to the nature of the process the steel used in galvanizing is rarely of premium quality.

For those interested in the nature of galvanizing process, here is a description from Intl. Chemtex Corp: In the galvanizing process, the steel to be coated is first cleaned in a caustic bath followed by pickling in a dilute hydrochloric or sulfuric acid bath. The steel is then subjected to a fluxing operation with a zinc ammonium chloride solution.

Sorry for the bad news but it's better to find out now than to be on your back sick as a dog...or worse.

[Hemi-T]

I would also be concerned about the foam insulation in the freezer panels. They are likely to be even more hazerdous than the zinc from the galvanized sheet metal. Foam handles cold real well, but not heat. Fiberglass works for hot and cold.

Hemi-T

[senna-the-great]

Thanks for all the help guys. I guess my good idea wasn't very good.
I dropped some powder coater off to a customer who has a high
restoration shop who also does alot of fabrication and he gave me
so good idea's on fabbing the frame.
Thanks again,
Art

[DALE]

This thread didn't take long to fill up. The only one missing is non-stick . These guys all have good points. Avoid galvanized! I use fiberglass because it's cheap and works well just don't compress it.You can go another way if you want--block walls then get high temp foam board to insulate it(not home depot board, get someting like fiberfax thats used in burn off ovens and rated at 1000 plus degrees. This would require no liner inside, it's very rigid and high r-factor. Light sounds ok and build with what ya got works for me.

[senna-the-great]

Hi,
I'm about to order steel today or tomorrow. The company I work for
build's diecast machine's that use industurail 220v emement's around the
melt pot's so there's a lot of electrical knowledge at my disposasal. I'll
keep you posted and add so pic's to the gallery if anyone would be interested.
Have a good day and hope it's warmer where you are,
Art