Fluidized Bed In A Pringles Can Paints Parts Inside And Out

Powder coating is a wonderful way to apply a smooth, colored surface to a part, whether for aesthetic reasons or corrosion protection. Traditionally, powder is applied via a air gun that sprays it towards a part while giving the grains an electrostatic charge. The part to be coated (generally metal) is hanging on a rack and given an opposite charge, and the powder readily flows to the surface and sticks well. The dry coated part is then placed in an oven which melts the powder into a solid, continuous surface. The main drawback of the process is that while simple parts with large surfaces are easy to coat, it can become difficult to get powder to flow evenly into deep crevices, or inside a hollow part such as a tube.

Enter fluidized bed powder coating — a process in which air shoots through a vat of powder, making it move like a fluid. A heated part can be dipped inside the vat, instantly melting a thin layer of powder around the part. This much simpler method is great at getting inside all those pesky crevices that traditional coating can’t touch, and hacker [Amper] was able to build a custom fluidized bed coater in a Pringles can. This rendition, inspired by this video tour of Dan Gelbart’s workshop, uses a coffee filter to evenly distribute the air flow supplied by a small compressor — [Amper] quickly learned that just sticking a tube in a bucket of powder results in more of a volcano than a nice, fluid surface. A burner heated up some pieces of metal that were then dipped them in the can, resulting in complete coverage, even inside the tiny 5 mm diameter hole down the center of a piece of 80/20 extrusion. Once [Amper] got the basic idea working, the idea scaled up into a larger machine that you can check out in the video below.

Powder coating is usually one of those processes though of as only viable in professional shops, but [Amper] along with some other intrepid hackers have done a great job demonstrating that it can be possible for the rest of us too. We’ve even seen some others experiment with fluidized bed coating before — it’s always great to see a process such as this one gradually become more and more accessible.

Thanks to [mip] for the tip!

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Simple Tip Helps With Powder Coating Perfection On Difficult Parts

To say that that the commercially available garden path lights commonly available at dollar stores are cheap is a vast overstatement of their true worthlessness. These solar-powered lights are so cheaply built that there’s almost no point in buying them, a fact that led [Mark Presling] down a fabrication rabbit hole that ends with some great tips on powder coating parts with difficult geometries.

Powder coating might seem a bit overkill for something as mundane as garden lights, but [Mark] has a point — if you buy something and it fails after a few weeks in the sun, you might as well build it right yourself. And a proper finish is a big part of not only getting the right look, but to making these totally un-Tardis-like light fixtures last in the weather. The video series below covers the entire design and build process, which ended up having an aluminum grille with some deep grooves. Such features prove hard to reach with powder coating, where the tiny particles of the coating are attracted to the workpiece thanks to a high potential difference between them. After coating, the part is heated to melt the particles and form a tough, beautiful finish.

But for grooves and other high-aspect-ratio features, the particles tend to avoid collecting in the nooks and crannies, leading to an uneven finish. [Mark]’s solution was to turn to “hot flocking”, where the part is heated before applying uncharged coating to the deep features. This gets the corners and grooves well coated before the rest of the coating is applied in the standard way, leading to a much better finish.

We love [Presser]’s attention to detail on this build, as well as the excellent fabrication tips and tricks sprinkled throughout the series. You might want to check out some of his other builds, like this professional-looking spot welder.

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Not Just Your Average DIY Spot Welder

Microwave oven transformer spot welder builds are about as common as Nixie tube clocks around here. But this spot welder is anything but common, and it has some great lessons about manufacturing techniques and how to achieve a next level look.

Far warning that [Mark Presling] has devoted no fewer than five videos to this build. You can find a playlist on his YouTube channel, and every one of them is well worth the time. The videos covering the meat of what went into this thing of beauty are below. The guts are pretty much what you expect from a spot welder — rewound MOT and a pulse timer — but the real treat is the metalwork. All the very robust parts for the jaws of the welder were sand cast in aluminum using 3D-printed patterns, machined to final dimensions, and powder coated. [Mark] gives an excellent primer on creating patterns in CAD, including how to compensate for shrinkage and make allowance for draft. There are tons of tips to glean from these videos, and plenty of inspiration for anyone looking to achieve a professional fit and finish.

In the category of Best Appearing Spot Welder, we’ll give this one the nod. Runners-up from recent years include this plastic case model and this free-standing semi-lethal unit.

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Powder Coating With A Fluidized Bed

There’s no beating the beauty and durability of a high-quality powder-coated part. There’s just something about the look and feel of the finish that goes far beyond mere painting and makes it worth the effort and expense. The typical electrostatic spray powder-coating setup can be expensive, though, and not necessarily suitable for every workpiece.

Enter the fluidized-bed powder coating chamber, perfect for limited runs of small parts, and the brainchild of [Andrew Mayhall]. With a business providing furniture kits based on iron pipe, [Andrew] needed a way to finish flanges and fittings, and powder coating provided the best look. The fluidizer he built is a great alternative to spray coating; it blows air through a bed of fine thermoplastic granules, which causes them to act like a fluid. It’s similar to the fluidized-bed hot tub we recently featured, but on a much smaller scale and with different requirements based on the ultrafine particle size and aggregation properties of the powder. [Andrew] had to add mechanical agitation to achieve a homogeneous fluid bed, and after much experimentation he’s now able to dip preheated parts into the bed and achieve one-step powder coating. The video after the break shows some of the operational details.

Does electrostatic powder-coating sound like more of your thing? No problem – DIY solutions abound, and a homebrew oven to bake your parts may be as close as the nearest file cabinet.

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Ink-Filled Machine Badges Score Respect For Your Gear

Remember the good old days when machines had a stout metal badge instead of cheap vinyl decals, and nameplates on motors were engraved in metal rather than printed on a label with a QR code? Neither do we, but these raised brass labels with color filled backgrounds look great, they’re surprisingly easy to make, and just the thing your gear needs to demand respect as a cherished piece of gear.

The ‘easy’ part of this only comes if you have access to a machine shop like [John] at NYC CNC does. To be fair, the only key machine for making these plates is a laser cutter, and even a guy like [John] needed to farm that out. The process is very straightforward — a brass plate is cleaned and coated with lacquer, which is then removed by the laser in the areas that are to be etched. The plate is dipped in an electrolyte solution for etching, cleaned, and powder coated. After curing the powder coat with a heat gun rather than an oven — a tip worth the price of admission by itself — the paint is sanded off the raised areas, the metal is polished, and a clear coat applied to protect the badge.

Plates like these would look great for a little retro-flair on a new build like this Nixie power meter, or allow you to restore a vintage machine like this classic forge blower.

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