DIY Powder Coating Oven Gets Things Cooking

[Bob] needed an oven for powder coating metal parts. Commercial ovens can cost thousands of dollars, which [Bob] didn’t have. He did have an rusty old file cabinet though.  And thus, a plan was born. The file cabinet’s steel shell would make a perfect oven body. He just had to remove all the drawers, sliders, and anything combustible. A few minutes with an angle grinder made quick work of the sheet metal. The drawer fronts we re-attached with hinges, allowing the newly fashioned door to swing out-of-the-way while parts are loaded into the oven.

The oven’s heating elements are two converted electric space heaters. The heating elements can be individually switched off to vary power to the oven. When all the elements are running, the oven pulls around 2000 watts, though full power is only used for pre-heating.

[Bob] used a lot of pop rivets in while building this oven, and plenty of them went into attaching sheet metal guards to protect the outside of the heating units. To complete the electrical equipment, a small fan was placed on top of the oven to circulate the air inside.

The most important part of the build was insulation. The entire inside of the oven was coated with aluminum foil and sealed with heat proof aluminum tape. On top of that went two layers of fiberglass matting. Metal strips kept the fiberglass in place, and the stays were held down with rivets. One last layer of aluminum foil was laid down on top of the fiberglass. Curing powder coating produces some nasty gasses, so [Bob] sealed the gaps of the oven with rolled fiberglass matting covered by aluminum foil and tape.

[Bob] was a bit worried about the outside of the oven getting hot enough to start a fire. There were no such problems though. The fiberglass matting makes for an extremely good insulator. So good that the oven goes from room temperature to 400 °F in just 5 minutes. After an hour of operation, the oven skin is just warm to the touch.

If you need to find [Bob], he’ll be out in his workshop – cooking up some fresh powder coated parts.


54 thoughts on “DIY Powder Coating Oven Gets Things Cooking

    1. I’ve got a pizza/toaster oven, a kitchen oven, and a fridge. Well, the shell of a fridge.

      Two points: insulation really isn’t all that important (you don’t need much), and don’t put the heaters on the side like that (on the bottom is easier and works better).

      And yeah, get a PID (most oven controllers are rubbish).

      1. I’d be worried about things dripping on the elements if they were at the bottom.
        I haven’t tried powder coating before. With powder coating, does it have to be heated in an oxidizing atmosphere or can you use propane or natural gas? (Reducing atmosphere)

        1. Powder coat doesn’t drip when it cured (well, it can, but if it does you’ve put it on too thick).

          People with huge oven use propane, you can only get so much heat from the power lines. Generally frowned upon for small ovens (fiddly, gas & powder explosions and all that).

          I guess they’d use some sort of heat exchanger as the byproducts from the gas burning would contaminate the part. And by heat exchanger, simply a box in the bottom of the oven where the gas burns, heat radiates through the top.

        1. They mention on the website that they are specifically ceramic (the old type) and not halogen. Halogen only warms what it hits and not the air. That’s not really suitable for powder coating.

          1. You’d get uneven heating with one heater stuck on the side like that. You’ll get weird convection patterns as well, but eh, it’ll work.

            A small air vent helps with air flow, they mentioned they didn’t add a vent as the fumes coming off powder coat are carcinogenic. That’s not true; powder coat is very low fume because it doesn’t have any solvents. Maybe they need to read the MSDS. The only danger from powder coat is a box of it falling on you.

          2. If the heaters were on the bottom, they would be blinded out with powder dust in no time at all. If you read the text, it says they have a slow fan at the top. I assume that is the black boc on the top. The main site has extra photos which shows a fan too.

            For powder coating, 2kW of energy might go in, but it needs to be evenly distributed through the air and not directly on the object being coated. Oherwise you end up with hotspots during curing. No emergency, but not ideal.

          3. If powder is falling off your parts in the oven, you’re doing it wrong.

            (You don’t spray powder in the oven, you have a spray booth for that)
            (For “spray booth”, a large cardboard box works fine)

            You’re right, they do have a fan. But putting an element on the side next to the part is still a fail, that’s a huge hot spot there.

          1. If I painted a trash barrel it’d be beautiful. I’ve just done a lot of painting up to now. In the course of my life I’ve got to admit, I’ve gotten pretty good at it by now too. In fact I can do things today that I used to think were impossible. Stuff like say getting a glass gloss clear finish with a brush on wood.

        1. But you said ‘Good enough.’ Good enough is not better. It is adequate, marginal, sufficient, nearly as good, that is: a substitute. Your later response is not just a non sequitur, it is a blatant contradiction. Then you attempted to offend afterwards.

          Why do this? How do you benefit? If it is to bring other people down or to troll, wouldn’t a larger audience make you happier or more satisfied? Reddit and youtube and facebook and all of those other places would be a better option. If it is in a genuine desire to improve projects, then why do you not use rationalism or substantiate any of your claims? Being actively hostile will merely galvanize people against what you say, thus the more emotional energy you put into your words, the less likely people will be receptive of them.

          As it is now, your behavior is not of significant benefit to you. It fails to provide positive external change and it fails to deliver a significant volume of negative responses.

          1. Kaowool doesn’t irritate your skin? It makes me extremely uncomfortable if I get it on me. I only ever get to play with it when it is old though, and we’re tearing it out of places. I’m convinced that it gets brittle with age, and breaks up more easily then.

      1. In the source article, they are talking about fibreglass matting, not spongy fibreglass wool. I would think the wool type would squash down over time, but not the matting. And yes, at less than $50, strip it all out every couple of years if you have to. It beats paying $5000 for an oven!

        1. Wool or matted, it’s still fibreglass. The max temperature isn’t all that high, but it’ll work for powder coating.

          Ovens aren’t rocket science, they’re a metal box with a heater.

          $5,000 sounds about right for a new one, but 2nd hand ovens are cheap. Cheaper than DIY at times. Especially when you realise that that powder coating / bakers / paint / etc ovens are all the same thing. (A kiln is something else).

          Wait until someone renovates and grab their kitchen oven.

  1. Looks pretty nice. I’ve thought about buying powder coat equipment in the past, but for the space it takes, I just have someone else do it.

    I’m surprised someone mentioned spray painting. I wonder if they’ve ever paid attention to the difference between paint and powder coating. Yeah, rattle can will get color on.

    1. pcf11 is a well-known moron here.

      Powder coating beats paint – especially shitty spray cans – hands down.

      Powder: clean, spray, cure. 30 minute turnaround, no clean up, perfect result.

      Paint: clean, primer, clean up, wait, sand, clean, paint, clean up, wait, sand, clean paint, clean up, wait, sand, clean, top coat, clean up, wait.

  2. Damn, very nice! Seems kind of like a waste of a file cabinet though, they’re the kind of thing that are sort of a pain in the ass to buy new.

    I’d been thinking about building a powder coating oven from scratch not that long ago– until now I’ve only been able to toasterize (haha) smallish parts in a Black & Decker InfraWave oven –by just making a big box out of sheet metal, and lining it with panels of stonewool insulation. Seems like it shouldn’t be too hard of a design to engineer, and you can make it whatever size you want. Sheet metal, insulation, some $20 infrared toaster ovens (Or space heaters, wherever you get your elements from), a PID, and a bunch of pop-rivets.

  3. Something I forgot about…

    If you are going to DIY your oven, you really need a window in it (use the glass from an old oven door).

    The reason is you (typically) bake powder for 10 minutes to cure it, however the time doesn’t start until the powder starts to melt (flow out).

    Even with small thin items it can take a couple of minutes, and of course if you open the door to check you lose temperature. Just because the sensor in the oven says it’s at 200C, that doesn’t mean the part is.

  4. What is pcf11going on about if that car was powder coated the finish would still be as good as the day it was done. I have only seen powder coating done with a negative iron spray gun if that is the right name for it and the finish is fantastic and with paint a little scratch and the rust spreads but with powder coating it does not so I know what I would use.

  5. Wow! I would never think of turning an old filing cabinet into an oven. I think it is brilliant you lined the inside with aluminum foil. Do you have to replace the foil often or is it pretty durable for your purposes? I want to try to make a smaller oven out of a 2-drawer filing cabinet. Do you think I would have enough space to attach all of the parts?

  6. Water heater blanket on the outside of the cabinet, if you want to put foil inside, whatever but it’s not really going to make a difference so long as it’s all sealed well. Much easier to insulate on the outside of something like this vs the inside. I have a and old paint cabinet used for a compressor shed, protects it from weather and is super quiet. Used a 2 door filing cab for the basis of a blasting cabinet, Roomy!

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