Taping Bobbin before winding

[Jeff Callahan]

I know I read this somewhere, but now I can't find it...

I wound many perfectly fine single coil pickups without taping the magnets to protect against shorting out the wire, but finally it has happened. I now believe in the process, but can't remember what kind of tape is typically used.


Thanks again,
Jeff

[Yves]

IMO you want some tape that is:
- not conducting (obvious)
- thin enough (to minimize impact on coil geometry / distance to the rods)
- heat resistant (not to melt / mess during potting process)

Now, that leaves you with quite a few choices indeed.
I use this:
Farnell Export

[Zhangliqun]

I use humbucker coil tape.

[Dave Kerr]

I bought some Kapton tape on the recommendation of someone here (David King?) - the stuff is thin and very tough.

[Jeff Callahan]

Thanks Dave,
I tried Teflon because it's thin, but doesn't seem strong enough. I've never heard of Kapton, can you get it at MSC or McMaster-Carr?

Thanks,
Jeff

[Yves]

For some reason the link to Farnell that I posted below isn't working (I've already noticed that, I guess it is due to their dynamic nature plus location sensing). I am trying another one plus the datashet FWIW:
3M|F1350Y-12MM|TAPE, POLYESTER, 12MMX66M | Farnell United Kingdom
http://www.farnell.com/datasheets/311289.pdf

I find Kapton to be somewhat over priced fo such a use.

[Jeff Callahan]

Thanks for the help, I'll try it. Found some from Uline, but I'll check other sources before ordering.

Jeff

[Joe Gwinn]

I tried Teflon because it's thin, but doesn't seem strong enough.

Exactly. A big problem with teflon tape is that it's soft and flows under pressure (creeps), so wires under tension will slowly "swim" through it, causing problems. Mylar, kapton, paper, and the like are much better for bobbin taping.

The pressure at the bottom of the coil in a bobbin can be quite large. For example, consider 10,000 turns wound at 20 grams of tension. Each turn contributes the tension twice, so the force trying to shorten the bobbin is (2)(10000)(20)= 400,000 grams, or 400 Kg, which is 880 pounds. Now in practice, the bobbin will yield a bit, and the wire will stretch a bit, all somewhat reducing the force, but still it's easy to generate considerable forces.

[copperheadroads]

i have used floral tape around the magnets & outside to wrap the wire its adhesive is wax works really well easy to remove if you need to repair you can buy it almost anywhere i buy it at walmart and the dollar store

[big_teee]

The problem with taping a strat type single coil, it takes up some valuable room.
I use lacquer, or clear finger nail polish and take my chances.
Terry

[Bruce Johnson]

Plain ol' Scotch Magic Tape, the standard office supply stuff, is pretty good. I'm not sure what the plastic is, but it's thin and tough and has good adhesive. I don't do wax potting, so I don't know for sure, but my guess is that the tape's film would hold up fine under those temperatures. The film thickness is probably about the same as a coat of lacquer.

[Joe Gwinn]

Plain ol' Scotch Magic Tape, the standard office supply stuff, is pretty good. I'm not sure what the plastic is, but it's thin and tough and has good adhesive. I don't do wax potting, so I don't know for sure, but my guess is that the tape's film would hold up fine under those temperatures. The film thickness is probably about the same as a coat of lacquer.

The film is acetate. I know for sure that Magic Tape withstands the tender mercies of a domestic dishwasher, at 60 degrees C (140 F). The tape does not come off of whatever it was stuck too, and the adhesive does not seem to have been changed in any way.

I don't know if hot wax bothers the adhesive, but my guess is that it does not, at least not quickly, so long as the tape is applied to a clean bobbin having no residual wax. Once the winding is in place, the wire will keep the tape in place.

As for tape thickness, I measured a piece scrubbed down on a 3x5 card with a micrometer good to 0.0001". The thickness of the tape+adhesive is 0.0019" (0.048 mm), call it 0.002".

[RedHouse]

Exactly. A big problem with teflon tape is that it's soft and flows under pressure (creeps), so wires under tension will slowly "swim" through it, causing problems. Mylar, kapton, paper, and the like are much better for bobbin taping.

Definately operator error, that problem vanishes when you stretch the tape as you wrap it on (or before hand) as it was intended to be applied.

Teflon tape has considerable give, but yeilds to it's maximum at a certain point, then you wrap it on the bobbin and the wire wont "swim" anywhere, it lays down right on top and goes no further. I've been using it that way for years and never had it cause any problem. Even un-wound old winds to check it, IMHO, it's the best/cheapest/most readily available choice.

YMMV

[Scott S.]

I use 3M number 56 tape, mylar 1 mil thick, it is very common in transformers and such

http://multimedia.3m.com/mws/mediawe...VVVeEWfr7777t-

[Bruce Johnson]

Thanks, Joe. So, it's acetate. It really is pretty amazing tape. On one of my pickup models, I cast the bobbins in an upper and lower half and press them onto the magnets. Right where they come together, I had a problem with the wire wanting to catch and fall down into the gap. One wrap of the 1/2" wide Magic tape solved it.

Another amazing tape is the (3M) Scotch Packaging Tape. It's really resistant to most kinds of glues and epoxies. I use it on surfaces of fixtures and tooling, any place likely to get glue drips. Even nasty epoxies just fall right off it.