Powder Coating Oven project

[DAC45]

I thought a few of you might be interested in this. A few years back, I purchased a powder coating gun from Harbor Freight and I picked up a little oven for 20 bucks at a garage sale. I started powder coating a lot of the stuff I was welding or machining but soon came to the conclusion that the oven was too small and the gun too weak for multiple coats. I looked around on the internet to see if I could find a bigger oven for a decent price. I looked for pizza ovens, scientific ovens, proofing ovens and all sorts of things. They all had their problems not the least of which was price. Too small, 3 phase power, not hot enough, too big or 1000 miles away.... So I decided to build an oven. I figured I'd want it to be 4'x3'x3'. But wait, what if I want to do a motorcycle frame? Or a bumper? Or a bike rack? The size then became 6'x3'x3'. I was going to make it out of 2 inch thin wall square tube. Some sites on the internet suggested 3 inch, but when I looked at my little oven from the garage sale, no where did it have more than 2 inches of insulation and it seemed fine. What would I sheet it in? I was going to go wit 20 gauge steel, but happened upon some 12 gauge aluminum sheets that were 42"x 77" in a scrap pile at the local metal place. Apparently they had been miss cut so they were selling for scrap price of .30 cents a pound.
The next question was heating. How would I do this. I took my little oven apart and picked up a convection oven at a garage sale for another 30 bucks and had all the heating elements and controls, plus convection fan that I would need. I then jumped on the internet to find some length of temperature rated wiring and sealing rope for around the door and was ready to start welding and cutting.
I found aluminum was easy to cut with a carbide blade in my circular saw. While taking apart the second stove, I decided to use the little window for viewing into the new oven.
I used the unbacked fiberglass insulation for between the inside and outside panels.
I used a power junction box to wire all my controls into. The access for the convection fan also acts as a air expansion release. The thermostats from one of the stove controls the 3 2200 watt electric burners in the oven. I also mounted a temperature gauge in the window for more precise readings. I even reused one of the lights to illuminate the interior of the oven.
I'm attaching some pics. Let me know what you think or if you have questions.

[DAC45]

I also upgraded the gun. Next time around I'll probably stick to sheet metal sheeting as it would expand less when hot. Live and learn.

[67cudafb]

Very nice job on the powder coat ovens. How much heat does it take to cure the powder coat? What brand of guns do you guys use, eastwood,HF?

[Tritium]

Caswell Plating is a great site with a veritable wealth of information not just on powder coating but on plating of all kinds of metals from gold to black chrome.

Thurmond

[parkour]

The heat required will depend on the size of the oven, insulation quality, temperature, and time.
The required temperature is usually between ~375 and ~400 *F, for 10-20 minutes or so; but it will depend on the powder in question. The included instructions will specify those parameters.

[Trip59]

Do the stove top elements put out enough heat and in a reasonable enough time? Do you have anything like the OP mentioned to move the air or is it all convection based?

[DAC45]

I've been using a Columbia Coatings gun. It is the Hypersmooth gun at this link. http://www.columbiacoatings.com/product_p/hs02univ.htm. A couple of things I learned as I was going through the project include:
- Sheet metal would have been better than sheet aluminum due to the expansion of the aluminum when it is heated.
- You can buy all kinds of controllers that are digital and stuff on ebay, but the added expense doesn't seem necessary when you've got perfectly good controllers from the oven you cannibalized.
- Convection fans don't circulate the heat in a way that creates a draft which is perfect for powder coating as you don't want to disturb the powered.
- 3 standard oven elements heat the oven to 400 degrees in about 20 minutes.

[DAC45]

I've been using a Columbia Coatings gun. It is the Hypersmooth gun at this link. http://www.columbiacoatings.com/product_p/hs02univ.htm. A couple of things I learned as I was going through the project include:
- Sheet metal would have been better than sheet aluminum due to the expansion of the aluminum when it is heated.
- You can buy all kinds of controllers that are digital and stuff on ebay, but the added expense doesn't seem necessary when you've got perfectly good controllers from the oven you cannibalized.
- Convection fans don't circulate the heat in a way that creates a draft which is perfect for powder coating as you don't want to disturb the powered.
- 3 standard oven elements heat the oven to 400 degrees in about 20 minutes.

[DVA]

That is an awesome project. I have a co worker who is looking at making a powder coating oven. I will share this with him.

[acourtjester]

HI
That be a fine looking oven you built DAC45.
For those whom may want to build a powder coating oven the controls shown by DAC45 work good. But to have better control you may want to look into using a PID (digital programmable temperature controller) and SSR (Solid State Relay). This is a better way to control the oven as it has a sensor and can be preset to any temps needed for powder coating. There are different temps for different powders. This setup is very simple to wire up and use and will keep the temps constant. If you google DIY powder coating ovens you can fine lots of great info about calculating the oven temp/size/elements required for building an oven.

http://www.ebay.com/itm/Solid-State-...item19c8d04c56

http://www.ebay.com/itm/Dual-Digital...item1c1edac43a

You can also find the oven elements on Ebay.

http://www.ebay.com/itm/WB44X5043-OV...item3367daa800



Have fun
Tom

[NRM]

Nice build. Lets see some of the final products.

[parkour]

DAC45;
Ah, this is relevant to my interests
When you say you"I'll probably stick to sheet metal sheeting", do you mean sheet steel rather than sheet aluminum?
How much cleaning/prep of the part is necessary to get a good finish? Will it work reasonably well over mill scale, and maybe light rust, or does it need to be shiny bare metal? In any event, I would expect it needs to be free of any loose or oil contamination.

acourtjester;
Thanks for the ebay links. I was looking, but didn't find such nice parts.

[zoama]

HI
That be a fine looking oven you built DAC45.
For those whom may want to build a powder coating oven the controls shown by DAC45 work good. But to have better control you may want to look into using a PID (digital programmable temperature controller) and SSR (Solid State Relay). This is a better way to control the oven as it has a sensor and can be preset to any temps needed for powder coating. There are different temps for different powders. This setup is very simple to wire up and use and will keep the temps constant. If you google DIY powder coating ovens you can fine lots of great info about calculating the oven temp/size/elements required for building an oven.

http://www.ebay.com/itm/Solid-State-...item19c8d04c56

http://www.ebay.com/itm/Dual-Digital...item1c1edac43a

You can also find the oven elements on Ebay.

http://www.ebay.com/itm/WB44X5043-OV...item3367daa800

Have fun
Tom

I'd really like to here more about these controls and the setup if you're willing.

[acourtjester]

Hi parkour
Like any other coating you need to have a clean base to work from. Sand blasting is one that will give you and great start but you will then need to make sure the dust it also off the part. Check out this site http://www.caswellplating.com/powder/index.html for supplies and they also have a forum that will give you great info.
Where the problem is after you coat a part you then bake it so anything under the coat can gas out and mess up the finish. It is not very hard to do powder coating but just like welding you need to follow the rules.
Here is my oven and a bead roller I powder coated.
Have fun
Tom

[Trip59]

I have an oven I acquired when a neighbor was renovating... not as big as I'd like, but I figure it'll just run as it is for now. DAC45, what size convection oven was it?

Jester, what are the dims on yours? What are you using for elements?

[acourtjester]

HI
As for the time to heat up my oven it take about 30 minutes for the first heat up to temp. About 5 to 7 minutes to reheat after adding parts. This is controlled by the PID it shows set temp and actual temp. So you can see with the temp is in the oven at all time. The time starts when the oven has returned to the powders bake temp. I have a small vent but no air movement device in the oven.
Have it all hooks up together.
The PID is powered by 110 vac has temp probe input and power out to a relay or SSR. See attached wiring diagram. Both of these are small but the ssr can handle all the current you would need. The SSR controls the power to the heating elements.
I had a HF gun and still have a caswell 50KV gun it does a very good job. Simple to clean and use. Most of the low priced guns are the same looking the difference is the power supply. If you doing things with inside corners or applying 2 coats you need to bigger power supply then HF’s gun.
Basically the gun moves the powder inside the gun (fluffs it up) then blows it out. Along the way it puts an electrical charge on the powder so it sticks to the parts being sprayed. The power supply has a ground clamp that you attach to the parts or the hanging hook. I use a big cardboard box to put the parts in when I spray them to control the powder from getting all over the place. You can reclaim the powder that drops to the bottom of the box.

Have fun
Tom

[jerky]

this looks like a great little project for the winter. with my buddy opening up a shop, im sure i could find a use for it.

[acourtjester]

Hi
Mine is not quite two drums long, 23” diameter 50” long. I have two 2300 watt stove top elements being used and have two 1200 watt in there but not hooked up.
I found the two 2300 watts did just fine. I have parts to do another bigger oven but have not had the need or time. I would like to have one like DAC45’s only so much room in the shop! I put wheel on one end and move it around like a wheelbarrow and stand it up on end for storage.
Here is some other info about watts to oven size.
http://forum.caswellplating.com/oven...oven-size.html
Just remember you will need to hang the parts from something with small hooks.
You are melting the coating and it touches anything it will mark the finish even when you take it out. If you are cooking many part in batches you will need some place to hang them so you can reload the oven to save time and heat. I use a steel wire between two posts I make “S” hooks out of welding rods.

Have fun
Tom

[acourtjester]

I said 2300 watt top units they are 1200 and two smaller elements.
sorry
Tom