MTFCA Forum

I think it’s 3M-361 insulating tape. It’s on amazon but it’s not cheap. Older posts say it’s high and there are others that’s similar on amazon.

You can find it on the 'bay at $44.66 per roll. Yep, expensive but it's something you need.

Be careful that you don't spend more on tooling and materials to restore your own coil ring than a finished one from R.V. would cost.

I also read on one of the older posts that if you wanted to do your coil the cost was almost as high as buying another rewound. But that was several years ago. But it would interesting to try to do one. There is plenty of information on the forum on how to do a rewind.

Steve, reply to your earlier post:

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Post by jab35 » Thu Aug 13, 2020 12:38 pm

Steve: I've done one single stack, probably won't do another, the vendors do it better and faster.

I would never roast or cook a core to clean it, too much risk of warping the frame. The original shellac was a bigger challenge than the oil, I washed off most of the oil with kerosene, let it dry and then soaked in denatured alcohol softening the shellac until I could remove the coils without damaging them, since I re-used the copper. (I think all rewound single stack are done these days with new copper strip, I think double stack still re-use the copper) Various solvents, scotch pads and even course steel wool worked for me to clean up the strips. I made sure there were no dings in the strip that might work thru the insulation. Before I rewound the copper I stretched each strip about 4" (~4" in 12' = ~3% strain) which made it straight and flat.

I used McM-Carr p/n 7574A11 fiberglass tape for the between layers and overwrap insulation. That tape silicone insulation is rated up to 500F and is 0.007" thick, comparable to original paper insulation thickness. I split the 1/2" wide tape for application to the strip and used full 1/2" for overwrap. The original Ford overwrap was cotton twill according to one source I talked to.

For the insulating washers between the coil and frame I used 0.020" thick fishpaper, available in sheets from McM, thinner might work better for between coil insulators on double stack.

For final topcoat insulation, clear Glyptal 1202 electrical varnish. I first 'glued' the fishpaper discs and individual coils to the ring with the 1202, waited a day, made and verified the electrical connections and then saturated the entire assembly with liberal brush coat of the varnish. (Apply liberally, don't just give a hairspray coating from a spray can like some videos show). Let it cure a day or two and then bake at 200F for an hour to finish cure. The 200F and one hour bake is from the Glyptal manufacturer, and there is very little smell from the oven.

Andre shows how it all goes together and his work is excellent. RV has excellent products, and very fair prices.

Have fun, jb

Be careful that you don't spend more on tooling and materials...than a finished one from R.V. would cost.

The tooling won't be much, but the materials may add up to about $100-$150. I need to do more shopping around. I do not like it when shipping costs more than the product. Thanks to all for the info.

Steve, if you have an electric motor rewinding shop in your area check with them; they may be able to help with some of the stuff that you need.

Steve,
Here a few photos of what I use.
First there is the tool I made to make the coils. $2.-
The masking tape (polyester based and stand oil when used properly). Here I found it in about every "do it self shop". $2.- each need two.
Cotton tape 3/8" large needed about 1.3m each coil makes a little over 20m. You can find it at a sewing shop by the meter or 5 meters.
Last time I bought it was 200m for $57.- all in.
The coating here you can find the polyester resin for $16.-/liter available in 1/2liters. One liter does four coil loops.

I think for about $15.- you should find what you need to do the rebuild.

Good luck
Andre
Belgium

Hi All ;
Do one of you know ,where we can buy NEW Isolated copper strip . ???
Thanks for your answer .

Toon

Steve, I'll bet, you probably noticed when that chunk of stuff came off your coils that they weren't wrapped with any of this high faluting electronic Mylar tape...for one thing it wasn't around back then and for another, it would've been too expensive to Henry to even think about using. Nope, Ford (being the cheapo he was) used just plain old fashioned Friction Tape, that same black cloth tape you get over at Harbor Freight for a buck and a half a roll. And if you've noticed, the winds are very tight and close (about .250 to .375 at the crown with .125 at the center) Then they either spread or dribbled a potting solution (probably tar or varnish and not a lot of either, the idea was to seal the cloth weave to keep it from coming unraveled) on them to seal them, same thing you're going to do with that spray on electronic varnish...so it really doesn't matter what you wrap them with, you're going to seal them anyway.

When I had mine apart a couple of the coils had gotten damaged by the magnet plates that went bouncing about inside the engine, one put a sizeable dent in the bottom of one of the dips on the inspection plate and the other decided to have a bit fun with a couple of coils on my magneto....I re-wrapped the outer covering with (you guessed it) friction tape I got at Harbor Freight, didn't know how much it would take so I bought a couple of rolls of it. Re-wrapped those two, made sure the polarity was correct and re-potted them with stick varnish (one thing about us old piano tech guys, we've always got a few sticks of varnish around...we use to fill holes in a piano, then re-drill for the screw or glue things together with).

They've been in there for over 3 years now and it is running just fine....so give some thought to the old fashioned way of doing things and forget all these fancy grade tapes....Black friction tape works and it is what Ford used also!

Here is link for tape for coil wrapping. Find a motor rewind shop close by and ask them. They should be able to dip your coil.
https://www.eis-inc.com/electrical-insu ... -ph2212101
Or do yourself a favor, call RV . Dan

You will also need insulation paper for the doughnuts.
https://www.eis-inc.com/electrical-insu ... m/c-ph2112

I think Martin Vowell makes a good point. I noticed the same thing about the mag coil tape years ago and thought it looked about the same as plain old friction tape that had deteriorated over the years. The tape that’s mostly used nowadays will last longer but I have to say that what Ford used originally lasted at least 50 years or longer. That’s pretty good considering the newer tape will probably last at 75 or more years!
And that’s fine to use better materials and I‘m glad that’s being done.
,

Steve,

I did one just for the experience and it was a good experience. I may have tape left (3M Glass Cloth tape) for the coil wrapping and Kapton tape used to insulate between the wires. I will will give it to you if I still have it. Will check on that tonight.

Randy

I have rebuilt hundreds of mag coils and never saw anything that looked like friction tape on an original Ford coil. Only 1/2” cotton coil wrap tape. Dan

There is no friction tape in a genuine FORD field coil.

I would imagine there were (and has been since) many “spurious” manufacturers and rebuilders who did some pretty dicey work...

The original coil wrap was cotton twill (no adhesive) saturated with shellac after installation.

I will will give it to you if I still have it.

Thanks, Randy, but I found some.


Model T-Tips now has a video on mag coil rebuilding. Mike Bender sent me this link to it:
https://www.youtube.com/watch?v=VTNQiabdZp4