Powder Coating Oven

[getastro]

Hello there, I was wondering just how hard would it be to build an oven from sheet metal and heating coils from an oven. You see that I have a few large parts and would like to do them in an oven rather than with an IR lamp. I have electrical knowledge, but not sure how to go about building this oven. Do I build, an inner & outer box, wrap the inner with insulation? Any help would be great. Thanks.
P.S. Pleas save the speech about fire hazards and stuff like that. The two powder coat companies in this area run homemade oven year round.

[jdrax]

I am also interested in building an oven. I am currently using an old kitchen oven but would like a taller one so I can hang longer parts. i had the same idea of using the heating elements from the old oven and the thermostat and controls.

my biggest question is how large of an oven will these elements heat to the needed temp.

also is it possible to add more elements if need be and still be safe.

[DALE]

I use a home built oven every day and this is my third oven so far, they seem to be growing. Yes an easy way to build is sheet metal box insulated and put inside another box. That may be over simplified but an oven is not complex. Place a low speed fan outside the inner box with the shaft protruding inside with a metal fan blade for circulation. Elements and controls are your preference, many different types will work. Keep one tip in mind when building an oven, design the oven so that it will accept hanging parts or racks. I have seen a couple of ovens that would not support even 20 pounds. Insulation is your choice, I use home insulation, fiberglass type with paper backer removed. Remember to not try to build an air tight oven it will need to expand and contract. If you use sheet metal (steel) then you will have to preheat the oven and allow the oven material to heat soak before it will stabilize the temp.

jdrax -- you can add more elements easily but sounds like you may need wiring help if you have to ask. Most home ovens are 220V but they only apply 110V to each element and they usually only run one at a time unless set at preheat. I used the preheat setting all the time when I used a home oven. Check your elements they may be labeled 110 and 220, meaning they can handle both, if you move them to a bigger oven you may need to rewire them for the higher voltage to get the warm up time down to an acceptable level. Be careful and don't hesitiate to call a heating element manufacturer and pick their brains. Good Luck its not hard if you use common sense and also side with safety over economy.

[getastro]

Thanks Dale for the info. One more quick question is how do you wire you elements? I have seen each wired to a separate breaker then to a master breaker. I am not sure how they had the temp control for the unit. I have knowledge with electric and have wired 110V & 220V. Thanks for the fan idea.

[jdrax]

Dale,

when you build your ovens do you use an angle iron framework to start with? What thickness sheet metal do you use?

is it possible for you to email a photo to a person?

I have a lot of capability but just not in building metal boxes. i have had a body shop for over 20 years, have built trailers for 10 years, just never built an oven before and i know there are certain concerns that need to be addressed before i go off half cocked.

another thing, for the door, what type of seal do you use?

how big of an oven can normal kitchen elements handle?

[DALE]

You could use an angle iron frame if you intend to hang heavy parts but be realistic, do you intend to load this oven by hand? My current oven is built out of .040 stainless steel and .050 aluminum sheet. I didn't weld anything, it's all drilled and riveted with high temp silicone in the seams.I used tempered glass in aluminum channel frame. the seals are high temp inflatable. Don't set your sights this high and the aluminum and steel combo made for some interesting expansion problems to overcome. If you use steel try to use steel for most everything this will eliminate alot of trouble for you. 18 gauge or 20 gauge should do ok.The steel will also help stabalize the temp.You probably could get away with a rope seal used for fireplaces it's not very expensive and is easy to get, try a hardware store. I prefer latches that will give way in a miss-hap. Or use spring loaded hinges to hold door closed it's cheap and easy.Elements are not expensive how big of an oven do you have in mind? You can add more later easily if you leave room for them.Don't forget high temp wire, a good relay and a low voltage controller with a thermocouple to activate relay.The better you insulate the smaller the elements and I didn't insulate the bottom.You should have min 2 inches but 4 inches is better on all sides maybe more on top if you have room.

[getastro]

Hello Dale, Thanks for all the info. I guess you have your oven hooked to 220V? Okay tell me if I am wrong here. Heating elements to relay / relay to 220V power (AMPS?) / relay to temp control. Question, how many amps for 8 elements? Box is going to be 4’x4’x5’ wrapped with 6” insulation. Does this seem like over kill with elements?
Thanks for all the info.

[jbento]

I am a true novice, but I can see that building an oven is more need than want.

Since I do not consider myself very handy, does anyone have a set (or could make a set) of plans and a material list for building one? About 3'x3' should suffice.

Of course, if someone wanted to build me one out of the goodness of their heart, I would of course pay for materials and shipping...

Thanks!

Joe

[DALE]

getastro
Yes I hooked mine to 220v. The reason for this is because elements increase in wattage drasticly when you go from 110 to 220. The wattage doesn't double its more like 2/3rds. Example 500 watt element on 110 is aprox 1500 watts on 220. Wire your elements in paralell the you can add or subtract elements without alot of wiring changes and it's gonna give you more heat faster this way. Amps start with a 30 amp box and then down size fuses till they pop then step back up one size or get an amp meter and know for sure I recommend the later. Are your elements labeled? what is the wattage.If you don't know then start with 4 and see how it goes, don't trust you controller at first put a manual thermometer inside and compare to controller for a while then tweak controller. Don't be supprised at the temperature swing you see home oven controllers aren't designed to hold precisely but they can be made to work if you toy around with them for a while.

[getastro]

Dale,
At this time I do not have any of the parts, just getting info. Do you use standard oven elements or industrial tubular heating elements? Let me ask a question about your wiring set-up. You run all your elements in a parallel circuit to a solid-state relay, then the relay is hooked to a 220V line, your relay is hooked into the temp controller. Is that just about it or am I missing something. I have the frame down and a good idea about the wiring. Once more thanks a lot for the info. Sure did not want to spend $8000.00 for a oven.