Powder Coat oven setup

All,

We are looking at creating our own powder coating setup. After doing some research, we have seen that it is fairly inexpensive, not too complicated, and the students can do the work.

[EDIT: New gun choice below]
We will be purchasing the following powder coat gun from harbor freight and some powderfrom them as well.

We will make a plywood box with copper hooks/pipes for grounding and mounting purposes, where we can spray down our parts.

The biggest question is what ovens would everyone suggest? We want an oven big enough to put our chassis bars in it (which i believe is around 33 inches?) and then any other parts we will need for our robot. If the game is similar to this year, our lift bars would’ve needed to be sent elsewhere, along with our belly pan. But everything else I would like to send into the oven we would purchase.

I know building our own oven is an option but I really don’t want to have to deal with insulating, temperature control, etc. I have looked into electric smoking ovens and to me, those seem like the best options. Anyone have a good electric smoker they have tried out for this purpose?

I know teams who just use a regular old oven range, they leave the door open and add a shroud that rests on the open door to work with longer parts. For small parts you can use a toaster too.

This also looks like a very easy conversion - but your school may not be happy with something that is home-made.

What is your budget for the oven? Thats a huge factor here. Making an oven to accomodate the parts you describe (all of them) is pretty straightforward, and there are some off the shelf options for controls/relays that make it stupid simple.

Also - the harbor freight powder is pretty crappy. I’d recommend getting some from just about anywhere else. We’ve used http://www.tccoatings.com/ pretty much exclusively for years. Never had issues with shipping, and prices are super reasonable.

They also sell several components for custom ovens if thats the route you do decide to look at…

-Brando

Just like Brando mentioned above that harbor freight gun is junk! i’d personally recommend the eastwood kit https://www.eastwood.com/dual-voltage-hotcoat-powder-gun.html

Also make sure you put some time in prepping parts before you powder coat them. Our usual work flow is to sandblast, acetone wipe then apply powder, bake! Make sure when your sandblasting you cover up any threads and precision bearing holes you have machined :ahh:

I’ve seen lots of people use the eastwood gun so I think I will order that instead! Lots of people supporting your claim!

One question I have regarding the sandblasting:
We get our aluminum from a local metal yard. I personally go get the materials as soon as they come off the train and get cut. We then usually throw them right on the CNC or router. Do we still need to sandblast the parts? Will it look alright if we decide to bypass the sandblasting?

We are going to get some acetone and latex gloves (that way we don’t get skin oils on the parts). Will that be enought?

The Harbor freight gun is actually quite good and by many accounts better than the Eastwood one. As Brando actually said it’s the HF powder that’s crap (which my experience aligns with).

We use Eastwood supplies, and have been generally happy with their products. Being in Hawaii with a higher humidity, I sometimes had issues with our powder getting clogged while spraying with our Eastwood gun. I’m not sure if a higher quality gun would help at all.
We have powdered without sandblasting parts and they turn out fine. You definitely want to get acetone and gloves to remove any traces of oils from your parts. Anything to rid of them should work fine, as we’ve seen too many times what happens when you don’t wipe it down thoroughly.

We prefer to sandblast all our parts, but it is not a necessary step as long as all oils have been removed from the part prior to coating. If you don’t want to invest in a sandblasting setup, scotchbrite pads work as well for light clean up, i believe 254 uses that process.

I’ve had good results by rinsing the parts in water to remove any coolant and then deburring the parts with Scotchbrite pads which also leave a more even finish and remove some oxide. Then we rinse the parts in water again to remove the aluminium dust. Finally they are degreased in a Simple Green solution. These steps should be done wearing gloves to prevent finger oils from depositing on the parts.

Acetone is more noxious than necessary IMO. Any industrial strength degreaser should work fine.

To get a durable finish, you need to remove the oxides. Aluminum forms oxides almost immediately so the it is already rusted when it comes off the train. The chemistry that will remove oxides has health and disposal issues so cleaning and blasting is probably a better option. As with any surface finish, the prep is as important as the finish.

The TechShop ARR site’s (sniff) booth was similar to this (albeit sheet metal sides rather than wood) with a small exhaust vent at floor level. The vent was used for paint dust control and you needed to put a couple of HVAC filters in front of it after turning on the vent fan before starting to apply powder. I believe they went with metal enclosure since it was easy to manufacture from HVAC materials and easier to wipe down… wood will be harder to get the paint dust off later.

They also provided two ovens, one for small parts (roughly a cubic foot in size and a HF product) and another that was large enough for a motorcycle frame.

+1 for the Simple Green degreaser (higher than normal concentrations) in lieu of acetone or worse.

For FRC? Sandblasting not necessary - though it definitely enhances durability in our experience.

More importantly, it sounds obvious, but I’ve seen countless issues for people new to the process…the parts must be DRY. Professional powdercoaters often bake their parts for a short time after cleaning to ensure a bone dry part before applying powder.

An alternative to sand blasting we have used before is chemical etching: https://www.amazon.com/TotalBoat-Aluminum-Boat-Etch-Quart/dp/B01N9O8SXA

It worked well, and was less work than sandblasting, but was also a pain…its also chemicals, so take that for what its worth for your team.

All these things help adhesion in some way, but we’ve certainly just slapped some acetone on a freshly cut part and powdercoated in a rush. My guess is that will achieve what you are trying to do.

-Brando

I’m not sure I totally agree. The powdercoat is essentially a plastic coating like an epoxy, it needs to bond to the surface of the aluminium. Now while removing the oxide layer will achieve a stronger bond it’s not necessary to remove it entirely to achieve a significantly durable finish for FRC. In fact in some aerospace composite constructions they intentionally build up a layer of aluminium oxide using a anodizing process to create a stronger bond.

For practical purposes all that really needs to be removed is the very outermost layer of oxide as it was the last of the oxide build up before the natural process stopped. While being poor for bonding it can also trap contaminants. Any process that abrades the aluminium sufficiently will remove that layer and open up the pores of the aluminium oxide creating a better layer for adhesion. Roughing up the surfaces also improves mechanical adhesion.

I’ve found pre baking the parts by heating them up to anodizing temperature and then let them cool down before coating can help also. Contaminants like oil and water can off gas and ruin the finish.

TLDR: Don’t worry about it too much. Keep your parts clean and oil free and you’ll be fine. Abrading the surface can help durability.

We got really good at powder coating this year and have pretty much nailed down a process that I think is easy enough for any team to use. We wire wheel our parts with an angle grinder and then clean them with acetone. We pre heat the parts and spray on the powder to the hot parts and then re bake them again for 15-25 mins. This seems to give the best finish. As far as powder coating setup goes spray your parts in a booth hooked up to a shop vacuum to catch all the loose powder. The oven is probably the hardest/most expensive part of the whole thing so we built our own. Our oven is a 3 burner 6 foot tall 3 foot square base steel box basically. If there is enough interest we can put a guide out on how to build it. We spent less than $1500 to make it but I can’t exactly remember how much it was so it might have been way less. Powder coating gun recommendation get a nice one. You won’t regret it. We used harbor freight ones for 2 years before realizing how awful they were. Spectrum 3847 has a good recommendation for a gun that I think is on their website but I can chime in later with it if people can’t find it. I’m on mobile atm. Otherwise powder coating is highly recommended it’s easy and saves so much time compared to spray paint/any other solutions.

I would love to see a BOM or at least the parts used in the creation of it. A box that size could fit an entire FRC robot so that would be great.

I do not think we would need that big of an oven though - especially since we are trying to stay away from welding since we have no one with welding experience and no sponsors to do it. Therefore all of our parts need to be assembled with pop rivets and can be individually powder coated

Has anyone used a pottery kiln for powdercoating? Does the increased temperatures compared to an oven impact its performance?

We just started a powder coating set up last year.
A local shop who specializes in powder coating gave us a few tips.
We do sand blast our parts.
Than clean very well
Pre bake the parts to dry and allow off gassing.
Spray powder on cool parts ( although you can do it warm as well)
We get powder online at prismatic powders. (Also we get some left overs from the local company )
We use the Eastwood gun.
We are a school team and got a large oven from our kitchen when they were upgrading.
It is a fun project, the students get a kick out of it and the robots look great.

Ovens are overrated and bulky instead use IR Lights and spend more time cleaning and preparing parts but if you wanna spend more money put it into the gun.

I have a couple of years experience in paint automation but my dad has over 30 years of experience. we have been talking about creating a new painting set up for our shop. we have a sponsor currently gives us one day turnaround and for a first batch and paints all of our larger parts. In house we us an old electric house oven to paint smaller parts and our key chains. for a gun using just the Eastwood gun which you should be fine with. With the sponsorship, paint booths are not on the top of our list of improvement the quality we get now is pretty solid for what it is.

IR LAMPS
100% with budget and foot print size for your constraints would recommend for any team to not waste space and money on an oven. I would instead buy infrared cure lamps and set up a vertical fixture to hold hang the parts. like in this video

PAINTING ALUMINUM
Aluminum sucks to paint why all those aluminum hoods on the Ford Explorers have splotches peal off. Because of this if you want your robot paint job to last over the season you should soak the part in a cleaner and then in to an aluminum etcher. this will give you the biggest help in quality in the paint job.

GUN
If you still want to spend money are truly looking to improve the paint quality with equipment you are better off investing in a better gun. Getting a good charge on the paint and part is a big factor helps with coverage of the paint on to the part. Also make sure your powder paint is stored and stays dry. moisture and oil from compressors can hurt the job too.

Not sure what extent you want to go in depth to for quality of paint, but feel free to PM me with any questions.
this is also a good video to help explain some of the process

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The DiscoBots bought a double oven we found on craigslist.
The oven was opened up in the middle to make a single oven. We used the oven this year to powder coat long parts.

We can post pictures of the setup if people are interested.

I’ve got a DIY oven I use for cerakote and powder coating my own projects.

It’s a ~50" tall locker with some cheap insulation and high-temp RTV to seal the leaks, and the heater coil from a toaster oven in the bottom.

Efficient? Naw. Safe? Sorta… Effective? Totally.