Powder not charging

[blackcamaros]

First, I want to let everyone know I ordered a Caswell Powder gun late last night after a very frustrating evening.

I purchased a Chicago Electric gun about a year ago and have been doing quite a bit of powder coating. Total, I’ve probably shot over 50lbs of powder. Over the last 4-6 weeks, I’ve noticed a lot more overspray, and I have been fighting coverage issues. Yesterday evening, I tried to spray black over a part that was previously sprayed with chrome back in April, and the powder pretty much bounced off. The ground was good, but I wasn’t even getting any powder on the ground wire. If I got the tip of the gun near the part, there was a small spark like a static discharge, but nothing major. I tried a part that was bare metal, and that didn’t work either. I ended up shooting both parts hot in order to get anything to work.

Has anyone else had this type of experience with the CE gun, or with any other gun? Is there a way of checking the power supply?

[Livinincolor]

Sounds like you may have several problems. The one problem I do know about is you cannot spray powder coat over a part that is already coated. I have tried and like you said, the new powder bounces off! The already cured and hardened powder does not seem to conduct the charge needed to attract the new powder. All previous coatings need to be removed unless it is real chrome plate which will conduct a charge. I have tried to put candies over chrome (powder) bases and it does not seem to work for us. As to the electric unit needing repair or not, I could only speculate. If the area you spray in has an electric charge already (maybe it is very dry there), that would hamper good results. If your spray area is already somewhat charged with static electricity, that won't help. I have often wondered if the guns last that long...actually, it' not the gun so much as the transformer. I would like to hear from others on a way to test the electrical output of the unit to make sure it is still good.

[Crimson]

Originally Posted by Livinincolor

Sounds like you may have several problems. The one problem I do know about is you cannot spray powder coat over a part that is already coated. I have tried and like you said, the new powder bounces off! The already cured and hardened powder does not seem to conduct the charge needed to attract the new powder. All previous coatings need to be removed unless it is real chrome plate which will conduct a charge. I have tried to put candies over chrome (powder) bases and it does not seem to work for us. As to the electric unit needing repair or not, I could only speculate. If the area you spray in has an electric charge already (maybe it is very dry there), that would hamper good results. If your spray area is already somewhat charged with static electricity, that won't help. I have often wondered if the guns last that long...actually, it' not the gun so much as the transformer. I would like to hear from others on a way to test the electrical output of the unit to make sure it is still good.

not true. you can heat the part up to about 150 and then spray the powder on the part that is already coated. I have done this lots of times.

[ShelbyCSXT]

Originally Posted by Crimson

not true. you can heat the part up to about 150 and then spray the powder on the part that is already coated. I have done this lots of times.

Livinincolor was talking about the powder charge electrically sticking. Which is what the thread is about (electrically sticking to the part).

But as far as what you said, my friends and i are noobs, but are learning quickly. We've been experimenting with dropping/flinging/spraying powder while the part is hot. For example, we coated this sun with Blue Bonnet, then sprayed Cream on small portions while hot. We coated the bells and chain with just cream. Click on the picture to see a larger version.

[blackcamaros]

Actually, until recently, I was doing multiple colors without preheating. On many parts, I will do a chrome coating and cure, then follow it up with a color, and wipe off the color powder to expose portions of the chrome, then cure. Then I would follow up the whole thing with a clear coat, all while the part is room temperature. I have one part that has five different colors, plus a clear.

I opened up the case for the power supply last night and found a little plastic box where all the wires were coming out of. I removed the cover from this, and found a loose circuit board (the screws had not been installed to anchor it down) and another plastic box with more wires coming out of it that was potted solid. I checked some of the components on the circuit board (diodes, small transformer, relay) and found them to be OK. The whole unit was made in China, so there is probably little chance to get it repaired.

I'm assuming it's something in the control box. When I first purchased the gun, the tip would jump a gap of almost 1/4" with a huge spark. Now it is more like a small static discharge from shuffling your feet on a carpet, just before the tip touches the part. Oh well.

Does anyone know what the specifications are on these hobby guns? What is the frequency and the voltage?

[Popeye]

I think most of the hobby stuff is around 12K to 16K DC... hertz I'm not sure of, it might be on the back of the case.
Sounds like a loose connection cause usually a transformer craps out totally.
IMHO

[seanc]

I ... found a loose circuit board (the screws had not been installed to anchor it down) and another plastic box with more wires coming out of it that was potted solid.

Does anyone know what the specifications are on these hobby guns? What is the frequency and the voltage?

The circuit board is simply a small DC power supply to feed the indicator LEDs and power a relay which turns the high voltage on and off via the foot switch.

The potted black box is the HV transformer. The input to this transformer is 120v/60Hz, so unless there's some fancy circuitry inside it (very doubtful at this price point), the output is also 60Hz.

Sean

[blackcamaros]

I believe I found the problem. One of the things on the circuit board is a bridge circuit. I had the circuit board laying on the black plastic box that housed the potted HV transformer and the circuit baord and the spark was dimished like it was bedfore, and the lights on the front were flickering a little. I proped the board up on edge, as it should have been if it was screwed to the box with the bottom of the board electrically isolated. Suddenly, the spark was jumping the 1/4" again. It appears that the board fell over and the back side was leaning up against the inside of the plastic cover, which I believe shorted out part of the bridge circuit. I'm going to spray some himiseal on the board and put everything back together and call it good. On the bright side, my Caswell gun was delivered at noon today.

Thanks for the help.

[mtnbiker]

Originally Posted by Livinincolor

The one problem I do know about is you cannot spray powder coat over a part that is already coated.

The already cured and hardened powder does not seem to conduct the charge needed to attract the new powder.

Please be careful when giving advice. Its obvious you have not been pc'ing for very long, because you are WAY wrong. You can easily do multiple coats... multiple, not just two... but 3 or more. Thats they way people get all the trick looking colors and textures.

You are right that the existing powder does not conduct... its not supposed to. The part is. Thats why you need to make sure the ground is good.