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Renron 10th February 2009 07:06 PM

Powder Coating on the Cheap
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Always happy to give back something to my fellow DiyAudio's.
Here are some tips to modify the El-Cheapo powder coating guns which can be bought for ~$70 TOTAL! What a great deal. No affiliation to any PC sellers, none.

Mine gun is a Harbor Freight El-Cheapo, there are others which are speculated to be the same gun re-badged. If your looks like mine it probably is from the same factory in China.

OK, first, the fluidization of the powder is VERY important and as it comes with the screw on upside down cup, it doesn't work very well.
I cut off both chrome plated copper tubes and installed (2) 3/8 X 6' vinyl tubes. One is for Air introduction to the relocated cup and the other is for fluidized powder delivery to the gun.

Next slide please.

Renron 10th February 2009 07:16 PM

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Next, on the other end of the 2 tubes, cut 2 holes in the lid of 1 powder cup. You only need to cut 1 (one) lid. Use brass fittings with barbed ends on the underside of the lid. (as shown) then add a length of the same 3/8 vinyl tube to the end of one fitting.
I used brass fittings with a barb on one end and threads on the other.
Seal the outside of the lid with an epoxy or similar hard substance. DON'T , DON'T use silicone to seal the top. You don't want silicone anywhere near you equipment. If you do and you get fish eyes, don't say I didn't warn you. :eek: (fish eyes)

Next Slide Please

Renron 10th February 2009 07:22 PM

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Remote Pot hose photo.
Add powder to the plastic jar and screw the lid onto the remote powder jar. Next connect the tube with the added short vinyl tube (inside the remote cup) to the short post of the gun. You can choose to either cut off the top of the post or drill a second hole in the post. I cut the rounded top of mine off. Attache the other hose to the curved pick-up tube. I cut that one as well, it may kink the delivery hose if you do not. Give it a try both ways.

Next Slide Please.

Renron 10th February 2009 07:29 PM

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Next, Add a decent quality pressure regulator, not a flow regulator... they are different. Add a dissecant moisture filter in line near the gun if it is not already installed.
While you are in the area make sure the High Voltage wire is attached securely, it helps with the static charge of the powder.

Next Slide Please

Renron 10th February 2009 08:12 PM

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OK, now that we have improved the fluidization and air flow to the gun and cup, we need to improve the air flow at the gun. Remove the plastic deflector tip at the end of the gun, it unscrews. Save it for the hard to reach tight places, we wont reinstall it right away.
Take a pair of long nose needle nose pliers and reach inside the barrel of the gun and remove the triangular shaped static charge inductor. (I made up the static charge inductor thingee) Still, remove the triangle piece, note the needle tips point to the front of the barrel. You'll notice the rear of the unit is flat. Take a rat tail file, and file down that flat side to a clean airflow shape. Some people have beveled both sides and found it to work well, I only filed one side because I wanted a Vortex type of flow. I don't actually see the powder coming out the barrel like a vortex, but it may help. YMMV. It is more consistent and even flow out of the barrel.

Next Slide Please

Renron 10th February 2009 08:18 PM

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OK, now the powder is flowing well we need to get it out the end of the barrel better. You may be wondering what the screw on the bottom of the barrel is for; it adjusts the air flow seperatly from the regulator. Open this screw all the way out, unscrew it and some have cut the tip off and just replaced the threaded part. I did not cut the tip off of mine, simply unscrewed it most of the way out. It seems to work well for me. Try it unscrewed, then cut it off if you wish. Your choice.

Next Slide please.

Renron 10th February 2009 08:38 PM

no more slides.....sorry.
To clean the gun and pick-up tubes, just unscrew the cap from the powder bottle, and blast a shot of compressed air up the pick-up tube. A giant puff of powder will come out the barrel of the gun, this is good, 30 - 40 seconds has cleaned mine perfectly. The beauty is each cup of powder has it's own top and stays dry, never gets mixed up with different colors. The top cap stays with hoses and gun.
You can now wrangle the gun into places and positions you could not before, it even works upside down!
I get a much more even powder flow and controllable pattern, easily cranks up to a flood if you want. This is without replacing the dispersion tip at the end of the threaded rod. When spraying powder I move the tip in small circles while moving across the object being sprayed.

If you have any tips or advice please share it with us.

Great websites with forums are; in no preferred order

The last one is one of my favorites.

Thanks for reading.

Renron 10th February 2009 08:45 PM

I thought I was finished.... precoating or Conversion coatings.

When sandblasting use aluminum oxide not glass beads, some have found out glass beads explode on contact and lodge inside the metal pores, only to melt out later when curing the powder causing fish eyes 0~0 Muy bad Ju-Ju. :bigeyes:

I wash everything in Acetone first, rinse (not really needed), Zinc Phosphate from the auto paint store. Rinse. PRE heat part to outgas, should be minimum 30* higher than the powder cure temp., preheat for min. 20 minutes, powder coat warm to hot if possible. Make sure your ground is clean.
Good luck,

wakibaki 10th February 2009 08:50 PM

Good info, entertaining presentation.

I don't have any powdercoating to do at the moment, but when I do I will certainly revisit this thread.


bear 15th February 2009 02:31 PM

Coupla questions.

Zinc Phosphate? Wazzat? A wash? A spray paint? A conversion coating?
On aluminium only? From the Auto Parts Store, really? What do they call it?

Does the Harbor Freight product include variable HV?
If so, what determines your settings?

Have you experimented with different base material formulation powders?


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