Is there another tape to use other than the 3M 361 as specified in the Club Electrical System book for wrapping the magneto field coil? I also need a few feet of the copper ribbon, well enough for 1 coil.. Any one know of a source?
I found a source of 1/4" tape for $8 a roll. It seems identical to the 3M 361. It came from a company called "Small Bits" or something similar. Not at home at the moment so haven't got the details, but I will post the info tonight. One roll was just enough for the whole job.
Please post the info. Thats a heck of a lot less money than the 3M product.
I wanted to wind my own coils, but after seeing the price of the tape, I decided to just buy a coil ring. Wasn't THAT much more money and I'm sure they did a better job than I could have. I still might do it one day, just to say I did.
Question for the electrical experts. In building my hand crank coil tester, I rebuilt the field coil windings using a common cloth medical tape. This tape does not conduct electricity. After winding the coils I coated them with electrical varnish. This works very well with no problems.
Now the question, why will this fail if used in a engine??
The engine is submerged in hot oil which could cause the tape to deteriorate. Check the tape on an original magneto. It might work fine, but not last as long as the fiberglass tape.
The company for the 1/4" cloth tape is at www.smallparts.com. The tape is elect. insulating tape part #ECT-04. It seems to be a fibreglass cloth tape the same as the 3M. All info given with due care but no responsbility taken!!
I used cotton strip same as Henry did and coated it with several coats of epoxy resin, two years ago and looks the same as the day it was put together I got the cotton strip from Mcmaster-Carr. I have lots left over, let me know if you want some
The copper ribbon in the mag coils, go to a shop that handles stained glass for making windows etc. They have a copper ribbon in 2 or 3 widths usually but I am not sure on the thickness. Is that is not available where you are email me and let me know how much you need and I will send you some. I have an old coil ring that is coming unwound on several coils. Also need the width of the copper.
Here are the Scotch 27 product details from the 3M website. The only thing that bothers me is that the max temp is 266 degrees. That could be okay, but also may be cutting it a little close. The scotch 27 uses a rubber based adhesive and I think the more expensive (higher temperature) tape utilizes a silicone based adhesive. I'd like to start winding my own field coils too, but with the expense of the "proper" materials, it does seem to make better sense just to buy them.
Adhesive Material / Thermosetable rubber resin
Backing Material / Glass cloth
Dielectric Strength / 3000 Volt
Maximum Operating Temperature (Celsius) / 130 Degree Celsius
Maximum Operating Temperature (Fahrenheit) / 266 Degree Fahrenheit
Tape Color / White
Tape Grade / Premium
Tape Type / Glass Cloth
Thickness / 7.0 Milli-inch (Mil)
I would think that the temperature ratings on the two 3M tapes reflect the adhesives ability to withstand temperatures more than the fiberglass. The adhesive is more a convenience than a necessity when wrapping the coils. Helps keep the tape where you want it until you're ready to coat it with resin or whatever. Once the coil is "encased" I don't think there'd have to be much concern about the fate of the adhesive.
In a past life, I worked for a company that used the high temp 3M product. When they discontinued the use of this product I got numerous rolls of the stuff and gave several to a friend who wanted to do his own mag coil rebuild. Worked well for him.
Thanks for posting the heads up Jeff, I just purchased four rolls on line. Price is about 1/6th what the Scotch brand costs. Heat rating is well within the temp of the oil bath for a Model T. Plus the tape will be sealed. Not a problem.
I have wrapped coils before and like Henry experienced, the biggest problem is finding a varnish that will hold up.
As the club electrical book says coat the coils with boat resin... Does anyone do this? I can get corrosive resistant resin, that withstands heat to 300 degrees.