Author Topic: Which varnish to use to coat the Secondary?  (Read 1709 times)

Offline FilipŠebík

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Which varnish to use to coat the Secondary?
« on: March 15, 2019, 10:11:53 PM »
Hello, I want to know which varnish should I use to coat the secondary coil, because the one I have is meant for wood and it messed up my coil's windings. The varnish contains: acrylic dispersion, polyurethane dispersion, water, glycol and additions

The cause may be because I didn't keep the coil rotating while it was drying so that may be the cause of this problem (I didn't experience the same with my micro coil)

I would buy this https://www.tme.eu/gb/details/ep108/encapsulating-materials/huntsman/cw5620-hy5610/ but it's not available in my country and I can't source something similar. So can you recommend me a varnish that you know works 100%?
Thanks

Offline Thunderstruck

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Re: Which varnish to use to coat the Secondary?
« Reply #1 on: March 16, 2019, 05:46:38 AM »
Hi Filip,

I use Ultimeg manufactured by AEV, UK.

Offline FilipŠebík

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Re: Which varnish to use to coat the Secondary?
« Reply #2 on: March 16, 2019, 08:27:24 AM »
Hi Filip,

I use Ultimeg manufactured by AEV, UK.
Hey Thunderstruck, I would not like to use spray varnish, because it takes hundreds of coats and more time to achieve a nice coat of varnish.

Here is the picture of my messed up coil after varnishing without rotating and leaving standing over night

I want to know if I can fix it somehow. The windings were perfect when I wound them but after varnishing they just warped.

Offline Thunderstruck

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Re: Which varnish to use to coat the Secondary?
« Reply #3 on: March 16, 2019, 08:46:24 AM »
It also comes in tins for application by brush.
I also used "Cabothane" Polyurethane Varnish - it is a lot cheaper.
As far as your secondary is concerned, I have no idea why it did that. If your windings were nice and tight to start with, only reason I can think of why they would go loose and jump onto each other is if your secondary form ( PVC pipe I guess ) reacted with the varnish and collapsed.
Or, windings were not tight enough and slipped down ( you mentioned that it was standing upright overnight ).

You can build a simple jig for winding and varnishing using an old windscreen wiper motor, it is already geared down and slow turning. Connect it to a lab power supply and feed it just enough power so it turns slowly, or better, you can use a cheap PWM controller from eBay.

As far as repairing that is concerned, I doubt that it can be fixed. Loose and crossed windings will cause problems later on.
I think you are better off starting again, instead of spending time and money on a thing that might not work.

« Last Edit: March 16, 2019, 08:51:40 AM by Thunderstruck »

Offline FilipŠebík

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Re: Which varnish to use to coat the Secondary?
« Reply #4 on: March 16, 2019, 08:57:54 AM »
It also comes in tins for application by brush.
I also used "Cabothane" Polyurethane Varnish - it is a lot cheaper.
As far as your secondary is concerned, I have no idea why it did that. If your windings were nice and tight to start with, only reason I can think of why they would go loose and jump onto each other is if your secondary form ( PVC pipe I guess ) reacted with the varnish and collapsed.
Or, windings were not tight enough and slipped down ( you mentioned that it was standing upright overnight ).

You can build a simple jig for winding and varnishing using an old windscreen wiper motor, it is already geared down and slow turning. Connect it to a lab power supply and feed it just enough power so it turns slowly, or better, you can use a cheap PWM controller from eBay.
I actually have a crashed car which I can take the windshield wiper motor off and a lab bench supply, but I also have a motor from a old printer and it rotates pretty slow at around 1 volt so that's what I will use. And I use a varnish from a tin can, so I have experience with them. But it bugs me out that I can't just buy a 100% or so polyurethane varnish. I don't know if there's a law that makes them illegal or something but I should check that out. Thanks for helping me

Offline Thunderstruck

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Re: Which varnish to use to coat the Secondary?
« Reply #5 on: March 16, 2019, 09:40:55 AM »
Get 2 caps that fit onto your PVC pipe ( secondary form )
Drill both of them in the center, put them onto the PVC pipe and put a threaded rod through the middle ( all the way through ), secure with nuts on each end.
Attach to your motor using a coupling ( or anything you can think of )
Mount everything on a timber stand.

Good luck !

Offline FilipŠebík

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Re: Which varnish to use to coat the Secondary?
« Reply #6 on: March 16, 2019, 09:57:55 AM »
Get 2 caps that fit onto your PVC pipe ( secondary form )
Drill both of them in the center, put them onto the PVC pipe and put a threaded rod through the middle ( all the way through ), secure with nuts on each end.
Attach to your motor using a coupling ( or anything you can think of )
Mount everything on a timber stand.

Good luck !

Cough* I actually do that for every of my other coils but this one was too big, but thanks

Offline Thunderstruck

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Re: Which varnish to use to coat the Secondary?
« Reply #7 on: March 17, 2019, 02:39:25 AM »
You should also see a doctor about that cough  ;D

Offline Teravolt

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Re: Which varnish to use to coat the Secondary?
« Reply #8 on: March 17, 2019, 05:32:48 AM »
I use minwax polyurethane which comes in a spray on or brushed on. I use a low tack tape like masking tape, blue tape, to hold it to gether and not loosen up and to hold it in case of a winding error breaking. hear is an example

https://www.loneoceans.com/labs/qcw/

Offline FilipŠebík

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Re: Which varnish to use to coat the Secondary?
« Reply #9 on: March 17, 2019, 09:33:50 AM »
You should also see a doctor about that cough  ;D
Haha

I use minwax polyurethane which comes in a spray on or brushed on. I use a low tack tape like masking tape, blue tape, to hold it to gether and not loosen up and to hold it in case of a winding error breaking. hear is an example

https://www.loneoceans.com/labs/qcw/
:O It's so expensive and the only place I can buy it from is amazon. Better stick with my stuff and the coil warped because I didn't rotate it. Now my small coil is rotating and holding strong with third coat

Offline Mads Barnkob

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Re: Which varnish to use to coat the Secondary?
« Reply #10 on: March 19, 2019, 10:46:50 AM »
I have used both polyurethane and oil based varnishes for my secondary coils. The oil based will never really harden up to epoxy levels, but it works just fine.

Do not mix and put on different layers with different varnish types. I tried brushing on one layer, then use a spray varnish for a 2nd layer, that ended up cracking due to cross reaction between the two types.

I have also written a great deal about wire varnish and insulation varnish 2/3 way down in my secondary coil design guide: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/secondary-coil/
http://www.kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics

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Re: Which varnish to use to coat the Secondary?
« Reply #10 on: March 19, 2019, 10:46:50 AM »

 


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