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Old 13th November 2011, 09:50 PM   #11
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Jer, this link may be a decent start for constructing a powder coat baking oven, the inside could be lined with cheap ceramic floor tile.. ??

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Doc
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Old 13th November 2011, 10:22 PM   #12
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I was going to build one by just stacking up some bricks.
But the fact of the matters is that the part doesn't need to bake for any major length of time.
Just long enough for the material to melt and flow out.
On my samples the coating did flow and caused it to be thicker on one side of the screen.
This told me that it need not be baked to long.
In fact after I had drop them off I no sooner than I walked in the door and the phone rang telling me to come pick them up,Had I known that I would have waited there instead driving home just to go back,I tell ya that was the longest 20 minute drive I have ever done!!!

Those were just samples that the guy did for me free in order to see if it would work at all.
I didn't get a chance to pursue it much after that becuase of stupid life's mistakes (dui) and it has taken me a while to get back into it since then.

The window screen material won't take as much heat as a large flat peice of steel.
it will take a little longer to heat up and will need more time to bake through.

My coater was coating big stuff and at the time he was doing big towable road construction signs and his oven was big for big parts even though he had to take the signs apart.
I think he was the same guy that I was going to have do the subframe of my 1981 Turbo Trans Am but I never got that far with it and it has been sitting in the garage since 1998.

Anyway it doesn't take long,once the metal gets to temp it is done, from the way he described the process to me!
Somewhere I have seen small parts done with some paint baking lamps but those lamps aren't exactly cheap either even for a small one.

But even if the coating doesn't come out perfect it is a good start as a base, and,can be resealed with some clear like I had to do.

But when I first built them there was no sealing required and work the first time as is.

I can not explain to you my feelings when I heard them for the first time and cranked up at even 10 feet away.
My gosh they even had a little bass in them,drums sounded impeccable.

Listening to some rainforest and nature sounds my dog thought it was raining out and refused to go outside thinking that she was going to get wet ! ha,ha,ha
She is from Florida too, and loves to watch the rain through the screen door.
She was definitely confused as there was no rain.

jer

Last edited by geraldfryjr; 13th November 2011 at 10:34 PM.
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Old 13th November 2011, 11:10 PM   #13
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I don't know beans about this topic, but will toss out some ideas. When they make high voltage insulators, internal voids are a disaster. I'd assume it's very difficult to apply a coating without bubbles, especially if sprayed. You may not be able to see them without a microscope.

Some people like to make and coat their own photographic film and paper. They use a blade-like device to coat with. It has short spacers to keep it the right distance from the surface, and a narrow slot to dispense the emulsion. They don't like bubbles!

Whenever I've used epoxies or potting materials, I've degassed them under vacuum. It can also be done with a centrifuge but IMO it may not be as effective. My guess is a good clear material that's been degassed, applied with a blade type device, should give a film with high integrity and maybe good voltage capability.
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Old 14th November 2011, 04:53 AM   #14
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I think the simple reason is that high gloss has high solid content. Best regards moray james.
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Old 14th November 2011, 11:15 AM   #15
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Quote:
Originally Posted by Conrad Hoffman View Post
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Whenever I've used epoxies or potting materials, I've degassed them under vacuum. It can also be done with a centrifuge but IMO it may not be as effective. My guess is a good clear material that's been degassed, applied with a blade type device, should give a film with high integrity and maybe good voltage capability.
I would second that,
without vacuum it's near impossible to make good HV insulator... it also removes water a lot. Thixotropic paints may help as well as slow drying (water based) compositions.
Spray paint capture the air as it flies or vice versa.
So the drying oven has to be more vacuume rather than heating.
Also it's fair to mention that:
finnish ESL maker (if memory serves right) would just put a thin sheet of insulator over the stator and melt it in oven
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Old 15th November 2011, 12:39 AM   #16
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Well, in short...if one had an excellent powder coater it would be the best way to go...since others had similar experiences as me with powder coating and it still needed to be sprayed, I think the consensus would agree that spraying with multiple coats of urethane, polyurethane, epoxy resin, (spray-able materials with high solids) is really the way to go.

CharlieM, Ill be in the market for a micrometer.... BTW great HV power suppy...looks like you grabbed one from my stash!!!
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Old 15th November 2011, 12:48 AM   #17
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I'll be getting my perf stators back from the powder coater in about 2 weeks. One coat of powder epoxy primer and one coat of flat black. I'm hoping they don't bend any of the panels. When I get them home I think I'll give them some additional coats of shellac.
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Old 15th November 2011, 01:49 AM   #18
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Originally Posted by dochungwell View Post
CharlieM, Ill be in the market for a micrometer.... BTW great HV power suppy...looks like you grabbed one from my stash!!!
Yeah, and I was so impressed how neatly your transformers were wired up that I wired up another power supply and tranny package (with the Antek trannys) to post on my blog page.

One thing I didn't do when I sprayed up my stators was actually test them using the power supply and a foil strip electrode, like Jer recommended. I may have used more coating thickness than I actually needed-- so far I haven't experienced any arcing problems with those panels.

I didn't mention this my blog page, but on the very first panels I built, one of them played for about 30 seconds before stator-to-stator arcing along a panel edge shorted out the panel and tripped the shut-down circuitry in one of my power amps. I ended up rebuilding those brand new panels; which was a tough lesson to learn-- that's when I came up with that 1/16" tape overhang and edge-wrapping arrangement to enhance the insulation along the stator edges (see the sketch on my blog page). No problems since.
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Old 17th November 2011, 01:53 AM   #19
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Charlie, I have built a jig to endure i get the 1/16" over lap. I have yet to get any arcing from an edge! (I wouldn't consider building a panel without it).

Well, gearing up for the weekend and panel spraying. My game plan entails a light 600grit sanding of the already sprayed (16) panels...then shoot them with a primer, then black enamel, then multiple coats of polyurethane....till Sunday.... if I'm lucky!then Arc test as described by Jer Fry.

When I built my first panels I arc tested it after powder coating and realized it need much more insulating coatings than just the 2 coats of powdercoating provided. I essentially added an additional 3 cans per panel. It was then the arcing was inhibited.

When I began a production run we sprayed several thick automotive clear coats on top of the Hysol (anti arcing aerospace paint), and it seem to arc through with 2,700v like you would have thought I used chrome paint!

What I failed to mention is that when I got the panels back with the Hysol alone is that we constructed about 6 panels more than half arced through from panel to center conductor wire running into the connection to the copper ring (this will now be insulated and black electrical tape will now be placed under the double sided tape, and in line with the stator tabs. (this caused the arcing which sounded like a fast 3 click per second sound radiating from the affected area mentioned.

So, I believe the primer will be instrumental to providing a buffer coating, and the rest for color and a protective coating, or so I hope...

There is still enough time for someone to suggest a miracle conformable high dielectric coating.... other than what I have described!

Doc,
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Old 17th November 2011, 05:14 AM   #20
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Default Test it first...

Quote:
Originally Posted by dochungwell View Post
Well, in short...if one had an excellent powder coater it would be the best way to go...since others had similar experiences as me with powder coating and it still needed to be sprayed, I think the consensus would agree that spraying with multiple coats of urethane, polyurethane, epoxy resin, (spray-able materials with high solids) is really the way to go.

CharlieM, Ill be in the market for a micrometer.... BTW great HV power suppy...looks like you grabbed one from my stash!!!
Before you coat your panels with Shelac test the idea with a sample piece of coated perf metal. I would have concerns with Shelac making a good solid bond to your base paint. If you are building curved panels check to see if the Shelac will stand the flex of the bend. You can test a sample before and after the application of Shelac to see if there is any woth while gain for your efforts. See if you can build 15 -20 mil of base insulation. It`s not likely you will be able to make it much thicker but that will buy you some insurance.
Still seems to me the issues of bonding insulated wire to a grid are far less than what you guys are trying to do. Love the look but seems a tough way to do the job. Best regards Moray James.
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