Farady?

[JTW37]

Yep, post your findings. I haven't had this situation yet either, but that's not to say I won't. Share your info, that's what this forum is about.

[PCT17522]

Originally Posted by FigureLLC

post away! i still manage to get those sometimes. there's not a gun hi-tech enough that won't let me make those!

Me too. I recently tested the fancy new Nordson model..."Prodigy" I think. It had all sorts of special settings for 2nd coats and it varied the charge output based on some sort of feedback about how much charge was accepted in the part...etc, etc. I still got the craters, just maybe not as many.

[Banditperformance]

Back Ioniation can and will happen to everyone. its a natural occurance with 2nd coats. In the Powder coaters handbook there is a really great discription of how and why it happens. Basically, the first layer of cured powder is acctually an insulator of electric charge. The charge builds up on the surface instead of being attracted to the substrate and, when charge becomes great enough, it dissipates off the part, blowing powder with it.

[FigureLLC]

Originally Posted by PCT17522

Me too. I recently tested the fancy new Nordson model..."Prodigy" I think. It had all sorts of special settings for 2nd coats and it varied the charge output based on some sort of feedback about how much charge was accepted in the part...etc, etc. I still got the craters, just maybe not as many.

the prodigy doesn't sound significantly different from the surecoat, besides the hdlv pump. i like the new console and the fast color change features sound nice. looks like the gun itself is the surecoat gun. the surecoat has the recoat/touch-up/deep cavity settings, and independently adjustable back ionization. i can still manage to make crators, though.

[Harleydad]

Originally Posted by uricad

Is anyone still having this problem, or was I the only one. I found a solution. If anyone would like to know what I did, you can email me at: uricad@mac.com

Well, what's the word? What is it that you think you've discovered?

[uricad]

Maybe I should sell this piece I made....... ...Anyone want to buy one? Seriously though, there might be some legal issues if someone doesn't do it right and they get zapped. Let me work on the wording.

[Harleydad]

Are you writing a book?

[uricad]

Originally Posted by Harleydad

Are you writing a book?

It's just a home made ion collector. Very simple, and it worked great(for me anyway). Okay, here it is. This is only what I did, I'm not telling anyone to do this. Sorry I don't have any pictures. I have trouble posting them. -email for pics.
I have a Caswell 50Kv gun and a better 100Kv gun. The Caswell gun is what I modified. I took a 1.5"w by about 2" long piece of copper pipe(clean), and drilled a hole in it on one end. This was so I could attach a wire to it with a ring terminal. You're going to bring that wire to the guns ground, it should be an obvious piece of metal on or around the handle. Mine is the whole handle. Attach the copper ring over the plastic of the barrel. Mine is flush with the end of the gun barrel. You don't want it to close to the electrode in the gun....I'm pretty sure it would zap the hell out of you(maybe kill) if there was an arc from the electrode to this ion collector(copper ring). You might need to rap the barrel with electrical tape, or machine a some type of plastic ring, to evenly center the ring.

I Another thing I noticed was that the ring only had to be grounded during the first dusting......and it does suck up some of the charge, meaning there's less powder attraction to the part. It's worth it though, no back ionization.

Like I said, don't try this. If you still insist on trying this, make sure the gun is unplugged.
I don't know if you've tried to make your gun arc to the part, but I have(with no dust in the air), and it arcs at about 1/8"-1/4"at 50kv.(BUT I HAVE HEARD OF LARGER ARCS ON THIS SAME GUN) So with the ring at about 3/4" away from the the electrode, I think there should be no arcing. Again mine worked and is still working great. If I see one of these for sale for this gun, I want a cut.

[FigureLLC]

do thinner parts back ionize easier? i've gotten better at dealing with it, but i just shot a sample of metal stud, and it BI'd badly on the second coat. i had my nordson down to 10uA, although i did get in *real* close to try to get powder into the corners of the stud. i shot this cold, too, which i wouldn't have done if this was a real piece.

[Blazin_Jason]

What gun do you have, surecoat? Also what type of tip are you using?