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Oven build questions.

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  • Oven build questions.

    I’ve been powder coating in a kitchen oven now for 10 ish years. I’ve tried making extensions on that to sneak a longer part in but the temp variation is to great without moving burners around. So going to build a bigger oven that will only be used once in a while for larger parts ( I mess around with snowmobiles)

    I acquired 2 heavy gauge electrical cabinets. I am currently making 2 out of 1 to get the size I’m looking for. Outside dimensions will be 5’x3’x2’. So 30 sqft - insulation ...according to numerous threads I’ve read 150 watts / sqft seems to be a rough estimate for element required so around 4500 watts.

    I have a. 100 amp sub panel in my shop with a 40a oven circuit so powers not a issue.

    My questions.

    I was was planning on using rockwool comfortboard 80 2” thick , but 2” may not be enough?

    Elements I was planning 2 x 2400w

    Where’s the best mounting location? Walls or bottom? Cover the elements to diffuse the direct radiation?

    thermocouple mounted at the back 2/3 the way up?

    Im using a omron pid that just has a discrete output and 2 alarm outputs. (Acquired) So planning on a 40a contractor with 120vac coil or a ssr that’s driven with 120ac ...I’m leaning towards the contractor just cause that 120 ssr isn’t that common. Thoughts?

    This is going to be a bare bones build nothing fancy.
    Last edited by sjs67; 05-12-2019, 05:45 PM.

  • #2
    The first time I started to build an oven for mob powder coating, I started with a box that looked a lot like that. I planned on using the box as it was and putting insulation inside, and then making another box to fit inside the insulation, from a Stainless fridge (commercial unit) interior box. All said and done, I tossed it aside for the options and never looked back. Time wasn't;t on my side to get it done. However, I see the potential in what you plan and think it can work well. Elements on the sides I'd bump them to 2800 or 3000 watt... (I recommend giving yourself some extra power, simply to recover after opening to load and unload, as the price of the elements isn't that much of a difference) and SSR's are EASY to come by in your chosen AC format. Look on Eby for a guy out of Austin Texas. Also educate yourself on FOTEK SSR Counterfitters... there's a good article about telling which is which online... Fotek has a great reputation and can be had for really decent prices. If you go with SSR's Plan on having great heat sinks to dissipate heat. The rest of your simple Bare bones process looks great. Not an ideal shoe for an oven to do parts that are large, even though the capacity looks good, there will always be the need to be super careful loading. This almost requires specific fixtures you can load and unload with the parts (A Cart or rolling frame to attach to). That is also the reason for the side mounted elements. Cart will roll on the floor of the may have to build a frame for tracks to control the cart... Good luck and post better pictures as you go... those look like postage stamps.
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    • #3

      Thanks for the feed back. ....Yeah it’s not ideal but was free. I’m thinking if trimming the door lip off and making a insulated door to open the front up level with the thickness of the insulation. Thinking of building a frame skinned with tin for the interior

      Do you think 2” of Rockwool is enough?

      What things could I do to improve this idea?
      Having issues attaching proper pictures. Makes them small.
      Last edited by sjs67; 05-14-2019, 10:30 AM.


      • #4


        • #5
          Generally everything I see is 3+ inches of insulation... You can try 2, but I'm betting on a a hot exterior at that level... I know there will be loss of volume in the oven if you insulate thicker, but it's safer, I think. though I don't agree with everything I see online, I do agree with the need for safety. Make the oven as safe as you can. you'll thank yourself as you go.
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