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Technical Building a powder coat oven for the shop

Discussion in 'The Hokey Ass Message Board' started by Roothawg, Sep 11, 2019.

  1. Roothawg
    Joined: Mar 14, 2001
    Posts: 18,680


    I have been reading on the internet about DIY powder coat ovens for a while now. Just trying to decide on if it is cost effective. One thing I can't seem to find is annual usage cost. Say if you run a home made 4x4x4 oven with 3 elements, what does it cost to run per hour? I know electricity costs vary across the US, but I am just ballparking it.

    The plan is to start out with the old conventional oven from CL or a yard sale, then move up as the need for a bigger oven grows.

    A couple of things are holding me back.
    1. The shear size of these things. They eat up a lot of space
    2. Return on Investment- Not sure how, if any cost savings will ever be realized.

    Have you actually built your own oven? What would you do different if you had to do it again?
    Last edited: Sep 11, 2019
  2. lostone
    Joined: Oct 13, 2013
    Posts: 840

    from kansas

    My brother started building one the size of a big double door refrigerator but not sure how far he got.

    I know he had bought some elements and was pricing temp controllers. I think that's about as far as he got although I think the cabinet itself was about 75 to 80% finished.
  3. Well, the size of the oven is up to you. I use an old full-size household oven, that allows me to coat probably 75% of the stuff I want to do, with the only parts I farm out are the ones that won't fit in my oven or blast cabinet. And there are plans on the 'net for ovens that break down for storage, they're not that hard to build and don't need anything exotic or particularly expensive. As far as power usage, I've never noticed any difference but I'm on a 'budget plan' where they average my yearly usage and I pay the same amount every month. But I'm only doing it for myself, so it doesn't get used all that often. If you're coating a lot of parts at once, it's about like cooking a really large turkey. A common cure cycle would be between 5-10 minutes at 450 degrees to get 'flow out', then another 20 minutes at 350 for final cure.

    As far as return on investment, DIY powdercoating is cheap... Probably 95% of the cost of having it done is labor once you have the equipment (blast cabinet, powder gun, oven, some incidentals), a one lb bottle of powder was about $10 last time I bought some (color does make a difference), less if you buy larger quantities and/or catch sales. One lb of powder is equal to probably 15-20 spray paint cans in term of coverage. I coated an entire motorcycle except for the frame, wheels, motor minus all removable covers, rear fender and tank with less than one lb of powder... it goes a long ways.
    Last edited: Sep 11, 2019
  4. tubman
    Joined: May 16, 2007
    Posts: 4,310


    I got a free used built in oven and built a frame with casters to mount it on. . It works great for small parts, and I am able to get a 14" wheel in it if it's not too wide. Unfortunately, all my cars have wheels 15" and up. I have thought about building a larger oven, but you're right about the space thing. I am constantly pushing mine from one corner to the other trying to get it out of my way. That is what has kept me from building a larger oven. I never even considered power consumption.
    lothiandon1940 and Roothawg like this.
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  5. 41rodderz
    Joined: Sep 27, 2010
    Posts: 3,071

    from Oregon

    O am interested in everybody's options and opinions on this as well.
    lothiandon1940 likes this.
  6. Budget36
    Joined: Nov 29, 2014
    Posts: 2,226


    Cost usage would be based on the size elements (watts) you use and the time they are on. With that you can figure out KWH that the electric company charges for.


    This link will make it easy for you

    Just remember you enter the value in kW...i/e 1500 watts is 1.5 kw.
  7. Rocky72
    Joined: Nov 22, 2008
    Posts: 161

    from Pa.

    Why not gas or propane , probably cheaper than electric .
  8. belair
    Joined: Jul 10, 2006
    Posts: 8,046


    Open flame and powder might not be a good idea.
  9. Yeah, powder doesn't like open flame or sparks; they caution you not to vacuum it up, it can explode your vacuum...
    Roothawg and lothiandon1940 like this.
  10. manyolcars
    Joined: Mar 30, 2001
    Posts: 7,789


    The powder coating business here uses a huge natural gas oven
  11. Which uses a heat exchanger of some sort to prevent open flame, as well as being vented to the outside. All things that would run up the cost of a home-built unit beyond what the electricity costs would be.
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  12. manyolcars
    Joined: Mar 30, 2001
    Posts: 7,789


    Actually, no. His setup is a long pipe with an open flame. No heat exchanger. Yes you can not afford it. He told me his cost for gas is about $2000 a month. But he does truck cabs and frames
  13. Roothawg
    Joined: Mar 14, 2001
    Posts: 18,680


    Interesting. For simplicity, I will probably use electric elements.

    I had thought about building the frame with big eye bolts on the top to allow me to hoist it up into the rafters to save floor space when not in use, but I have visions of Wile E Coyote and a bank safe....
  14. saltflats
    Joined: Aug 14, 2007
    Posts: 9,432

    from Missouri

    You can leave the oven door open and build a box that would come out the end of the open door to make it larger.
    If that makes sense.
  15. Roothawg
    Joined: Mar 14, 2001
    Posts: 18,680


    I have seen that done. I just figured for simplicity, I would build one to hold the stuff I deal with mainly. Rear ends,front axles, 15" wheels etc.
  16. Build one 2' x 3' x 6' and make it a 'top load'. That will make loading long items easy, and for storage tip it vertically, you'll only have a 2 x 3 footprint. Get a used oven for the electrical bits, buy a second element and power that through a relay so you don't overload the switch. If the oven has a broiler element, you won't even need to buy the second one, just move that to the bottom of the box. To improve efficiency when not needing to use the full interior of the oven, make a removable insulated divider and series a switch to operate the second heating element only when needed.

    Build the oven framework out of 1" x 1" thinwall square tube, double-wall it with light gauge sheetmetal, and insulate between the walls with fiberglass. The insulation doesn't have to be packed in there either; 1" thick will be adequate. The biggest hassle will be 'gasketing' the door. I'd suggest getting a couple of used ovens and rob the door gaskets off of them.

    Install a couple of 'rails' at the top of the opening so you can use crosspieces to suspend your parts. How you 'accessorize' your oven is only limited by your imagination...

    The real key to successful powder coating is getting the metal absolutely clean and dry. Sandblasting is by far the best method, most chemicals leave a residue that will spoil the finish. Once blasted, use new clean rubber gloves to handle the parts though the coating process. Any body oils will show up as a flaw in the finish.
    Last edited: Sep 12, 2019
    Roothawg likes this.
  17. Blue One
    Joined: Feb 6, 2010
    Posts: 9,723

    Blue One
    from Alberta

    I had thought of building a powder coating oven or just using a used oven to do some of the powder coating for my RPU.
    Since I only have a small shop I decided against it.

    We have a local professional powder coating shop here that does really nice work for a reasonable cost.

    The total for all of the parts I had coated for my project didn't end up to be huge.

    During my research I found that makeshift ovens are just that makeshift.

    A proper professional oven develops and holds the temperature using digital controllers rather than the on and off up and down temperature ranges in things like used home baking ovens.
    And they also have fans to distribute even heat like a convection oven.

    Makeshift equipment usually means makeshift results.
    Doing it right can be costly.

    I probably would have had just as much ( or more) tied up in equipment and all in the end.

    The only way I could see it paying off would be for multiple projects and maybe doing some parts for other guys for cash or trading for other work.
    Last edited: Sep 12, 2019
  18. My 'homemade' powdercoating setup has paid for itself many times over...

    I'll tend to agree that if trying to do large items (bigger than what would fit into a household oven) taking the parts to a pro is a lot easier. That's what I do, as I don't do large items that often and don't want the hassle of storing a large oven when it's not in use. But my lack of a large blast cabinet is the big factor; trying to do blasting in an open environment makes it very tough to avoid contamination, not to mention being very messy. Pre-coating prep is 90% of getting a good job.

    But I've had no issues with getting a 'pro quality' finish on the stuff that I do, and the convenience of not having to drive 40 miles one way to the coater, pay $10 or more per piece, when I can have a finished coated part inside of an hour after finishing fabbing it with .50 or less worth of powder is well worth it.
  19. Roothawg
    Joined: Mar 14, 2001
    Posts: 18,680


    Just for giggles I called a local powdercoat guy that is a one man operation. He is the cheapest around here. I just picked a random part to get a feel. I used a 1935-40 Ford frame. He quoted $575 for a single color add $200 for a clear or second color, like a hammertone finish. I thought that was reasonable. It's the little parts like engine brackets etc. where it would pay for itself.
  20. That's a very decent price for a full-size frame, and quite beyond the ability of a DIYer to do with good results.

    The last batch of coated parts I did I took all of them to my local coater as my blast cabinet is in dire need of maintenance. They consisted of a fabricated fan shroud, fan, battery tray and hold down, and a handful of small brackets/parts. The shroud was the only part that wouldn't fit in my oven. Total bill was $220, I could have cut that in half if I had done the smaller stuff myself.
    Roothawg likes this.
  21. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,647

    from illinois

    That's funny , instant image , man crushed by oven .....
    Roothawg likes this.
  22. About time there MR! A LOT of variables, and some good info given.......
    My .02c/suggestions....... Start with the small house oven....... Look for remodeled apartment buildings...... They switch over to gas, and you have 10+ freebies curbside, or you just say you'll haul a few away......
    Even with the house oven, when not in use, you can store things inside, as well as on top. It's just a box!
    For the power usage= Picture this scenario........... You have multiple things to coat. Your oven only holds so much. OR, you have a big oven that will hold a rear end, and then some......
    The jist...... Everything has to ready to get sprayed/cured. Once the first batch is cured (flowed out), where will you hang it to do so, and it has to be away from where your spraying the next batch. Multiple sprays= oven on full boogie= juice. Just say you have multiple items to spray...... The suggestions are good ideas about hanging in your oven =racking, but if you have another batch of parts to do, that equals multiple racks, stock oven pieces, or custom made. Then there's where will your parts be curing= gotta have that thought out too.
    It get's a lil in depth with things, and to figure out the where's/ when's........
    Now- if you just did one piece at a time, you could just kill the oven, open the door, and let it cool that way.....
    But, if your going to spray, you will find you want to do multiple items in the same color, so it's gonna take some reloading of the oven, the gun, and powder.
    And lastly for P's &Q's, different metals take longer to flow out/cure.....
    Just gotta be ready to do it, and be prepared.............;)
    Roothawg likes this.
  23. manyolcars
    Joined: Mar 30, 2001
    Posts: 7,789


    youtube has DIY ovens
    Roothawg likes this.

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