A few days ago I started a thread about the rebuild of a Model T generator field coil but it took a strange turn.
Here is what I found after taking a field coil loop apart.
The coils are windup anti clock wise and makes 88 rounds.
The wire is 1mm thick and is warped with a cotton like tissue. The insulated 1.2mm thick new coil wire I have here should be just right to try to do the job.
The coils are connected inside-inside ; outside-outside and inside-inside to make the N-S-N-S field polarity.
In the attachment a few photos.
Next will be the make of a mandrel to turn the coils.
I don't believe using a larger wire size is wise, but I'm no expert. The cotton-like tissue probably IS cotton!! Are you saying that the original wire is only cotton-insulated, no enamel? If so, and you're measuring the insulated section of the new wire and the bare old wire, you may have the same size wire.
The diameter of the old wire is without the cotton insulation, the new wire is all in.
The old wire has only cotton insulation, no enamel.
The cotton is black and very fragile. In some places it is missing and shorted so the field is useless.
One of the things I learned and did in the US Navy was rewire motors, you have to have the original wire size or adjust the number of coils, and then you could run out of space for the coils to fit! Then a dunk in varnish and bake, fun job. Loved serving on the US Pine Island, AV12.
Ah, so if the new wire measurement is with insulation, you should be OK. What does the old wire measure with the cotton on it? if it's close or even bigger, you'll have no problems winding the coils. I forget when AC Gilbert patented the enamel insulation, but prior to that, wire was all cotton insulated; and as you found out, it can be pretty fragile! Since most of us don't have an varnish dip and bake set-up we use Glypnal instead. Let us know how the process goes. BTW, even with the enamel insulation wire, the coils get wrapped with the bias tape; it keeps everything in place and provides some protection for the outside windings' insulation.
Thanks for the support.
I can have the wire also in 1mm diameter, this will be better I think.
About the Glypnal instead; I googled the name but can't find it. Is there an other name for it??
The magneto coils I made till now, I wrapped them with cotton tape, will the bias tape be better??
It's spelled Glyptal.