Powder Coating System

Powder coating equipment is not outrageously expensive but I only plan on doing it occasionally on small parts and I want to do it as inexpensively as possible. This build includes printable parts for both the power supply and the powder fluidizer (gun) to charge and deliver the powder. If you are a maker/scavenger like I am you will likely need to spend $20-30 depending on what you already have to hand or can find. 

The project was inspired by these YouTube Creators:

1. Homemade Powder Coating Gun Power Supply - by DIY Phil
2. Homemade Powder Coating Gun - by DIY Phil
3. DIY Powder Coating Videos - by Tinker Smith
4. Detailed Power Supply Information - by Tinker Smith

YOUR SAFETY FIRST! There are serious electrical, chemical and physical safety hazards associated with doing something like this. PLEASE give due consideration to your own abilities and preparation for personal protection.

BUILD INSTRUCTIONS: I will do my best to provide enough pictures of the parts and final devices to guide physical assembly. Instructions for assembling and adjusting the power supply circuit are well documented in the YouTube videos mentioned above. The first one by DIY Phil was about all I needed. Tinker Smith provides some good details and more options.

Beyond that I will be happy to answer questions to the best of my ability and take all the polite, constructive advice you would like to drop in the comments.

With a minimum of tinkering this system works well for my purposes and met my low cost objectives. I hope you find it useful too.

PARTS:

The electronic parts list might look a little frightening but it is not expensive. It includes:

• A plug in power supply that can deliver at least 6 Volts and 2.5 Amps but no more than 40 Volts and 9 Amps. (I had some spare power supplies in my stores so that is what I am using. These can be purchased for less than $10 online.)
• One XL4016 Buck Converter (Search this on Amazon or your favorite supplier: 300W XL4016 DC-DC Max 9A Step Down Buck Converter 5-40V to 1.2-35V Adjustable Power Supply. Currently less than $5 online.)
• One Arc Pulse Generator (Search for this: High Voltage Generator DC 6-12V to 1000kV Boost Step-Up Inverter Arc Pulse Generator Power Module High Voltage Transformer. Currently less than $10 online.)
• Bare 14 AWG solid wire for the electrode in the powder gun
• Insulated wire for connecting components inside the power supply
• Wire leads to connect the high voltage arc power supply to the powder gun and workpiece (I made my own from 16 AWG silicone wire and some alligator clips I had lying around.)
• I used an on/off switch and some barrel jack and banana connectors I already had to connect the external power and the leads to the powder gun but you could just hard wire it all together. NOTE: You DO need to be able to turn the power off either with a built in switch, unplugging, or with a foot pedal. The arc pulse generator is not designed for continuous use and will burn out if left powered. I run mine for bursts of no more than 10 seconds with a few seconds “rest” in between using a cheap foot pedal. This works fine for coating reasonably sized objects.

The printed plastic parts for the powder gun are sized to fit common 1" SDR-21 PVC pipe found in big box hardware stores in the US. It is commonly used as distribution pipe for lawn sprinkler systems. The inside diameter of that pipe is almost exactly 30mm and the outside diameter is close enough to 34mm that any difference doesn't matter. (NOTE: Living in the US means that I use inches as the main unit of length for all of my woodworking and steel fabrication projects. The rest of my design world is metric unless I get stuck somewhere in between. I thank you for your patience as I try to deal with both systems.)

Other parts to purchase or scavenge include:

• A cheap air blow gun and fittings
• Bottles for powder. I have included lid models for:
  • US soda/water bottles
  • US electrolyte/sports drink bottles
  • US medium bulk spice bottles
• A foot or so of PVC pipe as described above.
• A piece of ¼" tubing about 6" long. (I used copper plumbing tube I already had but any fairly rigid tube would be fine. The hole in the air diverter is 7mm in diameter so whatever fits or can be made to fit is good.)
• If you use the printed power supply box model provided here you will also need six 3mm x 30mm screws to put it together.

USAGE: 

The arc generators used in this build are not designed to be powered for more than a few seconds at a time. If you leave this device powered for more than 30 seconds or so you will likely burn out your arc generator. The videos that explain setting up the circuit will allow for voltages and amperage that let you run the circuit in slightly longer bursts. I find that bursts of  just a few seconds with momentary pauses in between work best for me in delivering the quantities of powder where I want them on the objects I want to coat. I found a $10 foot pedal switch online that works perfectly for me. If you would like more information about the duty cycle of this setup see Tinker Smith's YouTube video on the subject here.

DESIGN: 

I used three utilities that I need to mention especially for those who might want to modify the design files I am providing:

1. Fusion 360 - There is a free single user non-commercial version. 
2. OpenSCAD - Also free. This is text based modeling software. It does not take much effort to customize files when the author includes customization parameters in the design.
3. Threaded Bottle or Jar Cap Generator for Fusion 360 - This is a “Fully Parameterized Fusion 360 Bottle Screw Top Generator” created by Printables user @mscalora. It requires Fusion 360 for modification and @mscalora has done a hero's work in creating this amazingly useful tool.