Custom oven material and heating element help needed

[DarinReiss]

I need to build an oven just big enough to fit a barreled action in. 40" would be more than wide enough for my largest firearm project.

Do you suggest I build it with the 40" lengthwise or heighth wise? I though lengthwise would be the most efficient and also distribute heat the most evenly.

The depth and heighth would only need to be about 15 or 16 inches.

Could I build this with a 1.5" angle iron welded frame, skin the inside with 18 gauge steel, attach eye bolts to ceiling at various locations for hanging parts and use sheet rock for a couple of inches of insulation? Then make another 1.5" angle iron frame outside the sheetrock.

I figure a heating element set out of a normal oven would heat this size of oven adequately for powder coating.

For the door I still do not a good idea on window material, hingeing or sealing gasket material. I figured I might use glass or plexiglass for the window and gate hinges to hinge the bottom of the door. The top of the door could be latched with a gate lock or sliding lock. Just thinking out loud as I am sure if this would work well.

Any thoughts or oven pics would be greatly appreciated.

Thanks,
Darin

[non-stick]

Darin...... first things first. Everybody has a diffeent "school" of thought on this and no one in particular is right. Here's my humble opinion....

No "door" for visibility is needed. There may be one on a standard oven, but I have yet to see one on anything else but a lab-oven in industrial use. Just another point where you would encounter heat loss. Even if I were to put one on, it wouldn't be made of plexi as it would melt the first time you brought the whole thing up to temperature. Also, sheetrock would not be a recommendation I would give anywhere near that oven. Steel inside (usually a nice thick gauge),insulation suited for the aplpication inbetween and steel on the outside (not nearly as thick as the internal metal). Anything having to do with any part of organics (the paper on sheetrock for example) would not have longevity in this atmosphere and quickly degrade. All steel contruction ovens with a good grade of insulation between the panels is industry standard. The seal around the doors is usually a fiberglass reinforced cording and latches on the tops of the doors (which USUALLY swing open barn-door style) are of the "C" hasp variety. Think positive locking tumbler type. I'm sure you've seen them before.

Now... with that out of the way, let's continue on with your inside chamber configurations. As most in here would tell you.... the taller "hanging" type of oven would be the way to go. Inside dimensions of 20"W X 20"D X 40"Tall would be my suggestion. I say this for two reasons. First being that it's always easier to hang a part on a hook than it is to lay it width wise in an oven. Especially one of that length. One could fashion a simple hook and even hang more than one part in there at a time making the efficiency of the oven more viable. Let's say you wanted to hang one part in and start it's cure cycle. Go right ahead. Now you've just coated another part and wish to cure that as well. Go right ahead on that one too. Keep going until you have the oven full. Once the first part is done, take it out and replace with yet another one. See where I'm going with this? This is called "revolving batch coating" in the industry. A constant flow of worker and oven effieciency. If you tried that with a "lay down" type of oven... no doubt you'd have the worst nightmare ever trying to get the part in the back when you have 3 others in front of it. Here's the second reason, with a twist.....I'd also tend to make this oven 52" tall incase you wanted to build some sort of tray to put small parts on and bake something totally different in while all this is going on. Simply weld or bolt in metal angles every 6" evenly on both sides of the oven and cut 20" square (because squares won't roll around on you) steel bars to fit. A few in a row can support a tray while one or two below can support whatever you are hanging. Change part size? No problem. Just move the bars up and down to suit your needs. It's that simple. Want to do a lot of trays worth of parts all at once? Slide in a couple of bars on every level and you can have a bakery rack style chamber to cure in. It's certainly more useful to you in this manner than if it were a lot wider than taller.


But then again.... that's just my opinion ..... Russ

[DarinReiss]

Russ,
Thanks for the info. :P
Looks like I need to make several changes to my plan.
Thanks,
Darin

[DALE]

Mind if I chime in on this one?
Definately make it vertical and not horizontal. It's gonna be a hundred times more user friendly. My oven has glass doors and it was worth every bit of effort to use them. Home ovens have windows that are double layered tempered glass with an air gap between and for custom effects its great to be able to see the flow out.
Insulate with fiberglass home insulation it's about $20 a roll just remove the paper vapor barrior from it before installing.
20 gauge steel is more than thick enough if you use a steel frame even 22gauge will work ok.
Definately skip the sheet rock idea simply due to expense and fire hazard.
Racks are a major plus for an oven.
As for the revolving batch method, I recomend not useing it unless your oven replaces the lost heat very rapidly after door open&close. Otherwise you'll have a hard time with consistancy.
Just a thought or two.
Dale

[DarinReiss]

Dale,
Thank you VERY much! Your information helps me greatly.
I have trouble seeing where I would do more than one or two batches at a run. I do custom gun refinishing and usually don't do too many at a time so I can give a fast turnaround for the customer. I also do manganese phosphating (also will be my undercoat for powdercoating) and only fire up the tank once every couple weeks.
Would you recommend 2-3 inches of insulation space or more? I am planning on about 15-20 inches for the depth and width and 36-48 inches for the heighth. I plan on using a heating element from a old oven to heat the unit.
Would you recommend a light inside or is double pane window sufficient for letting in light to see the flow out?
Thanks,
Darin

[non-stick]

Like I said... different schools of thought, and not a one of them "not helpful". Thanks for chiming in Dale. I didn't know about the see-thru doors because outside of an open-chambered gas fired oven, I've never really seen them used to be honest. As for the "revolving batch method".... that's also something that's used with ovens and a quick re-claim rate on the heat. My bad.... I keep forgetting to "scale down the recipe" sometimes on these things. Dale.... good advice. Listen to what the man says. I know I do!..... Russ

[DALE]

Definately install a light or place a light near so you can shine it in.Being able to see in is great for the hobbiest simply because without experience it will tough for you to tell how long the part is taking to come up to melting temp.
The more insulation you install will make the oven more efficient go for 4 inches if you can, also don't compress the insulation the fiberglass loses R-Value the more you compress it. If you make a 4inch space for insulation then purchase 4 inch insulation.
Non-Stick you advice is very usefull but definately production based.
But it's easy to forget that many people here are hobbiests.

[DarinReiss]

Dale and Non-Stick,
Thanks. This really helps!
I contacted Anthony at Arkfeld Mfg in Norfolk, NE yesterday to see about his fab shop making a custom oven. They do farm tools, gun vaults, vault doors and just about anything else you could want. I told Anthony that I had an off the wall idea to build an oven for powdercoating guns. He got excited because he is working on doing ceramic coatings and has similiar processes. I didn't think he had ever been asked to build something like this and I was wrong. They have built some custom heat treat ovens and know the skinny on the suppliers and such for burners, etc for ovens. I am going to end up spending more than I originally thought but I think the quality will be worth it. Even if I do just do this part time.
I will post more information once I hear back from Anthony with a quote.
Darin

[non-stick]

I'm thinking if you take pictures and document it.... it would be something a lot of people here would find useful as far as informational purposes go. Keep us posted on your progress,bud. I have no doubt between your fabricator and Dale's ideas you are well on the way to success.

[duke]

dale, what do you think of using insulated coolroom panels to make an oven. i have access to 2nd hand panels through a friend.

cheers duke