MTFCA Forum

Was the magneto coil wrap cotton or linen? Has anyone tried wrapping their windings with 100% lite weight cotton twill?
Comes in 1/2" too.
https://www.twilltape.com/lightweight-1 ... yard-roll/

depends on if it was a formal wrap or just a family event

Scott..OK that was a good one! Thanks for the

Mark: I talked with Mark Fleischaker (Total Re-coil) shortly before he passed away and he told me Ford used 1/2" Cotton Twill and that's what he used. jb

Fantastic! That should drop the cost considerably. Once the varnish is on, should last as long as the original did. Now the really big discission, do I want black or white?
https://www.twilltape.com/1-2-2/

Mark I couldn't help myself...

I've never wrapped mag coils but have done a bunch of starter coils and my go-to was cotton twill and then impregnated in polyurethane. They come out beautifully. The way the tape is woven you can get a really nice "lay" with no wrinkles and tight wraps if you are careful.

I switched to black tape as soon as I proofed my process:

I used fiberglass tape from an electronics store and after assembling everything, I coated everything with boat resin from a local marina. I have two of the ones I rewound in two of my Model T's for about 20 years so far no problems.
I followed the instructions in the booklet "Electrical System" published by the club.
Norm

I will still use the self stick fiberglass between the wraps. Going to do my 1/4" one first. I can buy the 1/4" off the shelf. When I am ready to do the 3/16" would make a slitter to size the tape.

One thing I would point out is that with the cotton twill, you can bias the tape one way or the other and it will remain perfectly flat against the project, when pulled tight. If you are using any other tape which will kink or buckle when tugged sideways or other direction, you'd want to avoid that.

I've never used fiberglass tape in this fashion but would suspect that it is very unfriendly when tugged hither and yon during the wrapping process.

This is what I used back when I was wrapping some, I decided it was much easier to let someone else do it. I put one I wrapped in the 23 I’m building now.
I have several rolls left if anyone is interested.

Mark, I'd use white, I doubt the black dye is conductive, but using pure white cotton eliminates that possibility. FWIW, Glyptal 1202 insulating varnish (clear) is a good product for sealing/insulating the mag ring assembly.

The fiberglass tape I used didn't seem terribly unfriendly.
I expect it will last longer than cotton.

cotton lasted 60+ years in starters, generators and field coils, so I'm planning on mine outlasting me. Considering that everything gets coated, if it deteriorates any sooner, something went wrong with the process.

cotton lasted 60+ years in starters, generators and field coils

Yep. I don't expect I'll be around long enough to know how well my coil ring holds up.

jab35 wrote: ↑

Sat Feb 04, 2023 10:50 am

Mark, I'd use white, I doubt the black dye is conductive, but using pure white cotton eliminates that possibility. FWIW, Glyptal 1202 insulating varnish (clear) is a good product for sealing/insulating the mag ring assembly.

Ordered the white and plan on sealing with the Glyptal varnish. Darn, Snyders is out of stock on the insulators, so guess I will have to make my own!

Have fun, Mark. I would not worry about the longevity of cotton twill if the assembled unit is fully saturated with the insulating varnish. The wicking action of the twill draws varnish into the wrapped coils. Baking the air-dried assembly @ 200F for two hours enhances the properties of the cured varnish. Quoted from Glyptal 1202 specifications: "Although primarily an air-drying varnish, the oil, moisture, acid, and salt water resistance are greatly improved by baking. GLYPTAL 1202 has excellent adhesion to most materials."

One tip I'd offer regarding the Fishpaper washers that go behind the wrapped coils against the mag ring frame. Instead of making the outer shape a uniform oval matching the outside geometry of the coil, make that profile more pear-shaped, so you have extended the insulation to the area where the coil leads are crimped and soldered, that way you have insulation between the ring frame the soldered joints in the copper. I know Ford didn't do the and most rebuilders don't bother, but Total-Recoil did and I think it's insurance that costs nothing. I used 0.020" thick Fish paper that I obtained from MM-Carr. Best, jb

If you will visit a local motor shop they can hook you up with the correct tape and if you ask nice will dip your coil for price.
When I was rebuilding coils it cost me $10,00 a coil for dip and bake. That was on the 80’s. I still find my coils in engines sent to me for rebuilding.

Light-weight or heavy duty cotton twill tape? Any particular size? ie: 1/4, 3/16 or maybe 1/2?

I use 10mm cotton strips 130 cm long for the single oval and 140cm long for the others.
After assembling and testing the loop, it ge three coats of polyester coating.
Work fine for me.
Andre
Belgium

Thanks everyone for the posts and suggestions. Will see how it goes now.