Magnet insulation

[Possum]

I thought I'd throw this out there and see what washes up on shore. As a matter of course I tape my magnets to insulate them. I've tried lacquer dips of various types and brands and no matter how loose I wind the coils short to the end poles. Nail polish the same thing. I have my old Fralin pickups laying here, the ones that got me into pickup making because they would never give it up through any guitar or amp I tried them through. So I cut the coils off, so out of curiosity I put my ohmeter probes across the magnets and no reading. I pushed real hard tried to dig into them and no reading. The magnets don't look coated at all, so I took an exact knife and scraped into and sure enough they ARE coated with something that I could chip off. Whatever it is, its as hard as a super glue coating, and is matte finish, not gloss. I am real tired of using tape and looking for ideas what they might be using. I've research electrical varnishes and lacquers and sure they are made but you have to send out and RFQ and no one will talk to you unless you want to buy 50 gallons of the stuff, and I'm not even sure it would work either. I found some stuff made by Dolph but again, they don't answer email and you can't find anyone who will sell you one can of the stuff to try out. So looking for ideas. Its has to be a hard almost invisible finish , hard as super glue, be easily wiped off and not thick so you don't have crap all over the magnet tops and flatwork. Super glue would work but how would you apply it without gluing your tongue to your knee in the process. Joe Gwinn suggested marine epoxy paint but you'd have to mix up enough to dunk the pickup in so there would be alot of wasted product and probably too thick to use. Ideas?

[mick]

I'm glad someone has mentioned this because I was about to ask..., just wound some strat pickups several times ( PITFA that was ), same thing no matter how loose it was wound it shorted to the outside poles? was thinking of some kind of poly laquer? but not sure if it would work ? there must be something ,

And can I mention Q for a moment , mine seems to be around the 2.4 even on low wind numbers? this is with strat pickups , I was thinking that maybe the tape was something to do with it ?

Mick

[J S Moore]

How about vinyl sanding sealer? Takes about an hour to dry and I am sure you can make it thin enough if it isn't already. Apparently it leaves a nice finish on the pickup as well. I read on SK's site that he uses it for potting and it will probably work for what you want.

[mick]

"How about vinyl sanding sealer? Takes about an hour to dry and I am sure you can make it thin enough if it isn't already. Apparently it leaves a nice finish on the pickup as well. I read on SK's site that he uses it for potting and it will probably work for what you want."

I Thought about the stuff they use on floorboards after they sand , that stuff is pretty hard but it could be too glossy? I'm not sure if it's the stuff you mention .

Mick

[mick]

Just had a thought on this , the mags have a very slight oily residue on them , if it's not wiped off properly the laquer won't stick properly , maybe I need to dip my mags in some kind of cleaning solvent ?

Mick

[madialex]

Originally Posted by mick

Just had a thought on this , the mags have a very slight oily residue on them , if it's not wiped off properly the laquer won't stick properly , maybe I need to dip my mags in some kind of cleaning solvent ?

Mick

Hi Mick, I use Deft Lacquer sanding sealer and I dip the pickup in either alcohol or when i'm out I have used fingernail polish remover to clean the whole bobbin mags and all. Just rinse it off quick, let it dry and dip them in the sealer, it leaves very little shine, it actually makes the bobbin look better IMHO. Takes about an hour to dry then you are good to go. I have baked them in the oven at about 140 to 150 for about 10 minutes to dry but I stress, be very careful, they put off a good deal of fumes when you do that, safest way is to just let them dry, hang them on some wire but make sure you wipe off the drip or it may dry like that

[Spence]

Use good old fashioned nail varnish. It's cheap, 1 bottle minimum order and dries in minutes. i opt for clear nail varnish though I have been known to use red and black. ( On the pickups that is. Just want to make that clear, so there's no confusion. Oh bollocks what have I saiD ...?... )

[mick]

Do you tell your mrs it's you who takes it and not the kids ?

[Possum]

So you're not getting pole shorts with this stuff and its virtually invisible when dry? Since you've been to Fralin's shop did you happen to notice what they're using? The stuff they're using dissolves in lacquer thinner so it can't be anything too exotic.

[Possum]

Where do you buy this stuff, Lowe's , Ace?
Nail polish never worked for me, its too soft, especially the sparkle pink with little stars in it :-) Seriously though I could never get it to work and tried various brands.....

[mick]

Hmmm , reminds me of the time I went out to the shops ( I usually go around barefoot ) with blue sparkle nail polish on my toes , I can thank my 2 daughter sfor that one , man did I get some looks...

Mick

[Spence]

Originally Posted by mick

Do you tell your mrs it's you who takes it and not the kids ?

Nah, bugger that. I never tell her anything. She has wondered why I never wear sandals when she's around though.....

[Joe Gwinn]

Originally Posted by Possum

So looking for ideas. It has to be a hard almost invisible finish, hard as super glue, be easily wiped off and not thick so you don't have crap all over the magnet tops and flatwork. Super glue would work but how would you apply it without gluing your tongue to your knee in the process. Joe Gwinn suggested marine epoxy paint but you'd have to mix up enough to dunk the pickup in so there would be alot of wasted product and probably too thick to use. Ideas?

Don't forget the part about thinning the epoxy varnish so it'll go on thin.

Another alternative is thinned urethane spar (marine) varnish, first air dryed, then baked in a toaster oven, to ensure that the film is fully hardened before attempting to wind. Don't forget to wash things in acetone first, to remove all grease before attempting to coat the magnets.

Why marine varnish? Because marine varnishes are the best one can buy at retail, and although they are expensive compared to non-marine products, it makes no difference in the quantities used on pickups.

Why does the film have to be so hard? Because the pressure is very large. Let's run a numerical example:

Take a 8,000-turn coil wound with #43 wire. The winding tension is something like 26 grams. The end magnets are therefore being pulled towards each other with a force of (0.026)(2*8000)= 416 kilograms, or 915 pounds. The effective area of each magnet bearing the load is about 3/16" by 7/16", or 0.0820 square inches, so the pressure is about 915/0.082= 11,157 pounds per square inch, on average. This well exceeds the strength of many plastics, both initially and especially over time as the pressure causes the inner wires to creep through the film

The pressure will be reduced as the bobbin crushes slightly and as the wires in the winding slide about a bit, and/or due to a loose wind, but still it's easy to get large numbers, so the coating must be quite hard right from the start to survive.

[madialex]

Originally Posted by Possum

Where do you buy this stuff, Lowe's , Ace?
Nail polish never worked for me, its too soft, especially the sparkle pink with little stars in it :-) Seriously though I could never get it to work and tried various brands.....

Hi Possum, sorry but I wasnt at Lindy's shop long enough to see a lot of things, though I was trying to take in everything I could. He mentioned a crazy glue he uses on the single coils for the magnets that has no fumes?? I didnt catch the name of the stuff but as far as the coating it didnt look like anything was on the prep;ed bobbins ready for winding if it was it was clear.

I got my deft from Lowes, a quart was like 4 bucks, its clear lacquer sanding sealer. I just dip the whole bobbin in for a few seconds and hang them to dry. As I said you will have to watch for that last little drip that will dry on the end if you dont wipe it off. If you dont want any shine on the flatwork at all just wipe the flatwork off after a few minutes and leave it on the mags.

To my knowledge I have had no problems with the coils shorting yet.

[Spence]

Something that springs to mind:

I seem to remember Possum telling me that the magnets are sometimes a bit loose in the flatwork and the effects of lacquering help to stick it all together. OK, that may be where the problem is. I say this because if the flatwork moves on the magnets, it will get trapped between the flatwork and the magnets on the end poles. in the process the coating on the wire is stripped and so is the lacquer on the magnets.
This oversize/undersize issue with bobbins and flat work is a right royal pain in the ass. In order to get around this problem, I always resort to using a set of reducing punches.

reducing punch.jpg

These are readilly available at Micro mark.

http://www.ares-server.com/Ares/Ares...oduct&ID=82390

Obviously don't use these on the side of the flatwork that shows.

Lacquer after.
My personal choice is Fiddes Bonehard Lacquer. I guess by the name of it, it's nitrocellulose with viagra in it !

[EtLa]

what I do is I clean the magnets with a mix of water/degreaser and when dry I dip the magnet in Varathane Diamond Water-Based Polyurethane and suspend it for 8 hours. Works perfectly well for me.

[Zhangliqun]

Or you could just assemble the bobbin and then just wrap the rods in tape.

[David King]

I'd think super glue is the quickest and cheapest coating one could apply. It's very tough if it gets good adhesion. Harder finish would be a two part polyester finish but you really don't want to get into that unless you already use it for guitar finish.
There is a low oder cyano acrylate glue available at most hobby shops.
Check out http://www2.towerhobbies.com/cgi-bin...?&I=LXM365&P=7

Hot stuff UFO thin. (UFO stands for user friendly oderless).

I'd apply it by dipping each magnet in the bottle, (after degreasing), let it drain and set it on a sheet of slick plastic to dry. You could also squirt it on the assembled bobbin.

Why not slide thin tubing over each magnet??

[mick]

I would be more inclined to dip the whole lot into something rather than just the mags ,it sort of holds the bobbin together too so it's about more than just stopping shorting . Just finding the right dipping agent that's tricky....

Mick

[Spence]

Originally Posted by David King

I'd think super glue is the quickest and cheapest coating one could apply. It's very tough if it gets good adhesion. Harder finish would be a two part polyester finish but you really don't want to get into that unless you already use it for guitar finish.
There is a low oder cyano acrylate glue available at most hobby shops.
Check out http://www2.towerhobbies.com/cgi-bin...?&I=LXM365&P=7

Hot stuff UFO thin. (UFO stands for user friendly oderless).

I'd apply it by dipping each magnet in the bottle, (after degreasing), let it drain and set it on a sheet of slick plastic to dry. You could also squirt it on the assembled bobbin.

Why not slide thin tubing over each magnet??

With respect David, that's not a good solution for anyone trying to turn pickups out quickly. As I mentioned, the use of reducing punches reduced the hole diameter. Just a couple of hammer blows.

[David Schwab]

I think dipping the bobbin in something is more work than taping it. I just cut some strips of tape with a ruler and razor blade and wrap it around the poles.

I wonder if one reason for the shorts is the wire heating up as it's wound and melting through what ever protective coating might be on the magnets?

[David King]

Spence,
As brilliant as the reducing punches are I don't see how they would do much to insulate the magnets.

I think the cheapest, fastest and easiest dip would probably be shellac. It's low tox and reversable. A blond shellac like Zinzer Bullseye is pretty damn tough and the stuff will dry in minutes.

[Spence]

Well of course they don't. But they do reduce the hole that you hammer the magnets into. This is pre-lacquering. Obviously I didn't make myself clear enough. The idea of reducing the holes in the flatwork is so that the magnets have a tighter fit and therefore are less prone to move when winding and hence trapping the wire between flatwork and magnet. ( ...and breath...)
This sytem works. Even so, on some pickups I will reduce, lacquer and tape. Just do whatever is required but there's no need to get DuPont to develop a special coating for you etc....

[Zhangliqun]

Originally Posted by David Schwab

I think dipping the bobbin in something is more work than taping it. I just cut some strips of tape with a ruler and razor blade and wrap it around the poles.

Ah, a fellow taper. I was waiting to get flamed over it -- but I suppose the thread is still young...

Originally Posted by David Schwab

I wonder if one reason for the shorts is the wire heating up as it's wound and melting through what ever protective coating might be on the magnets?

It doesn't get THAT hot, does it? If it did, I would think the insulation would also melt from one layer to the next, especially on the ends where the turns are really packed tight together. Plus I would think the magnets themselves would act as a heat sink.

I've heard it kicked around that it's a slow chemical-ish reaction between the Alnico and the insulation that eats away at it. Sounds more plausible to me, but I'm hardly an expert on such things so I don't know.

[David Schwab]

Originally Posted by Zhangliqun

Ah, a fellow taper. I was waiting to get flamed over it -- but I suppose the thread is still young...

I don't wind any kind of vintage recreation, so it's ok.

I've used scotch tape, electrical tape, and white paper tape, depending on my mood. In my case I'm winding onto a steel bar, who's square edges have been ground and sanded, but I'd rather be safe than sorry!

I do see where taping magnets will add some space between the wire and the magnet, so that might change something.

Originally Posted by Zhangliqun

It doesn't get THAT hot, does it?

Probably not... I was thinking out loud.

[Possum]

shellac sounds like a good try, the lacquer sanding stuff failed the ohmeter probe test, it was real easy to dig through it just like other lacquers so I know it'll short out, at least the way I wind. Nothing wrong with taping but the tape stops wax from entering the inside of the coil, what real effect that has I don't know, but I am trying to be more vintage correct and tired of taping. I think the UFO super glue sounds like a real good bet, the best I've heard here so far, I'm ordering some. Will try shellac this weekend....

[David King]

Shellac usually won't be as hard as most lacquers. What about a baked-on transformer varnish or even a powder coat? If you need it that tough you'll have a tough time finding something that isn't catalyzed in some way. Bake-on finishes or epoxy are less trouble because you won't be dealing with HAPs.
Just because that super glue is odorless doesn't mean the fumes won't kill you.

[Spence]

Sounds like Police interrogation of eastern Europeans I know but just to be serious for a minute:

Fender also taped the poles for a short period. Concerns about wax not penetrating the inside of the coil did not come into it because they were lacquering the coil by then. Some winders like Wizard poke holes in the tape between the magnets to allow a free flow of wax. But if you have to resort to using tape, you only need use it on the outer poles.

[EtLa]

I use Water-Based Polyurethane that leave a thin finish and insulate pretty well, I suspend 6 magnets and at the end a dripping point that I made out of a 3/16" rod
http://www.rustoleum.com/product.asp...t_id=663&SBL=1

[Joe Gwinn]

Originally Posted by Possum

shellac sounds like a good try, the lacquer sanding stuff failed the ohmeter probe test, it was real easy to dig through it just like other lacquers so I know it'll short out, at least the way I wind.

I think sanding sealers are as a class going to be soft, by design.

Lacquers are expected to be hard, but some take weeks to fully dry, unless one cures them in an oven.

Nothing wrong with taping but the tape stops wax from entering the inside of the coil, what real effect that has I don't know, but I am trying to be more vintage correct and tired of taping.

Does vintage allow for an extra pair of holes in the bottom flatwork to let the wax in?

[Joe Gwinn]

Originally Posted by David King

Shellac usually won't be as hard as most lacquers. What about a baked-on transformer varnish or even a powder coat? If you need it that tough you'll have a tough time finding something that isn't catalyzed in some way. Bake-on finishes or epoxy are less trouble because you won't be dealing with HAPs.

This is why I was suggesting use of thinned two-part marine epoxy varnish. Available in small quantities from retail sources, and sure to work.

By the way, it is not necessary to mix the whole can at once. One can mix smaller quantities, just so long as one gets the ratio reasonably correct. And use two measuring cups, one for part A and the other for part B, and don't mix things up, or the entire can will be ruined. The cups should be different colors or shapes or both.

Just because that super glue is odorless doesn't mean the fumes won't kill you.

Correct.

[David Schwab]

Originally Posted by Joe Gwinn

I think sanding sealers are as a class going to be soft, by design.

This is correct. Sanding sealers are some type of finish, such as lacquer, with zinc stearate added. The stearate is a soft, fluffy soap, making it build up and fill in pores much faster. It also makes the lacquer softer, and acts as a lubricant when sanding.

I really dislike sanding sealers when used for finishing wood. I've always had adhesion problems, and the lacquer ends up chipping off.

[Ruel]

Would potting the pickup help? If it is unpotted then there is the chance that the wire will rub against the magnet as it vibrates and possibly cause insulation failure??????

[Possum]

There IS a hole in the bobbin top and bottom for mounting during winding but if you tape you put up a "fence" that seals off the coil from the interior so no wax gets past the tape.

The two part products are just too much hassle and too much waste for me. Plus expensive, the West stuff I looked at comes in Kits and are like $35. The Varathane looks interesting because it mentions scratch resistance. Whatever Fralin used is lacquer thinner solveable so I'm not sure its super glue after all. I tried some spar varnish and it didn't work either.

No potting doesn't help at all, the shorts happen before potting and its only the end magnets that are the problem. I am just taping the end poles but thats a hassle too. but it works....

[madialex]

Could it possibly be the wires fault? I mean maybe the insulation is thin and rubbing through at the pressure points? Do you use a lot of tension? You mentioned the way you wind, i'm not sure what you could be doing to cause this? I'm stumped.
Has this been going on for a long time or just recently? Did you switch wire companies?