Looking for resistive wire with shellac coating

They've got the right wire, but its not insulated. Magnet wire is coated OK, but not resistive. So I may have to look up technique for coating the wire myself. Anyone have a reference?

LOL ! It works too. ;~)

Graham

?I would have said, "Get some appropriate Thermocouple wire and use the Nichrome side and ignore the other couple half.

Yukio YANO

The usual stuff has glass cloth to withstand extreme heat when they say insulated. I am not going to drive current through the wire so the insulation is just to isolate the wire. I am willing to do a couple of coats of polyurethane or shellac, but don't know how to dry it without damaging the coating.

My current idea is to bribe a couple of kids at the ballfield to hold it aloft while I travel along the length with a triple pulley dipped into a pint can of the coating. It's ridiculous, but I can't think of anything better.

Don't use shellac. It's the wrong thing. It'll crack. Polyurethane is what typically goes on enamelled wire today.

Graham

Well, its very boring, but I'm simply making a ribbon controller. I've considered monolithic materials, but they're hard to find without actually buying and testing a lot of stuff. So by default I will wrap a nonconductive core with resistance wire and then remove a portion of the insulating surface.

Using the right words for a search helps. I did find suitable coatings by looking up "insulating varnish". Now looking for one that does not require heat treating. My wife is tired of experiments in the oven.

--- Well, OK!

Here's an old trick that might work for you:

Instead of winding a single uninsulated wire around the mandrel, paint the mandrel with some varnish and while it's still wet wind two separate strands of the wire around it, making sure the strands stay parallel, touching, and tight until the varnish dries/cures. Once it does, unwind one of the strands and Voila!, you're left with a nice coil of uninsulated resistance wire with none of the turns touching. Finish it by painting it with epoxy and wiping the epoxy off of the contact surface before it cures, (so you won't have to sand it off later) and there ya go!

-- John Fields Professional Circuit Designer

Using a sacrificial wire as a spacer is a good idea. It may not be as mechanically strong as I desired, but not having to pre-coat it would be a big time and effort saver. Thanks for the tip.

Several Suppliers sell Thermocouple wire as coated, insulated Pairs, in different gauges. Nichrome, Chromel are trade names for various Nickel/Chromium alloys. A Type K thermocouple is Chromel A/Alumel I recall ordering insulated Nichrome wire from OMEGA Engineering several years ago.

Google Omega Engineering, or try Omega.com

Yukio YANO

Thanks. Useful table here.

I would not have looked at iron-chrome-aluminum, but it has good properties for me. Might be expensive to just pull off the other side, but very convenient. Even easier to leave it in place and leave it unconnected.

We sell small quantities of resistance wire, both bare and insulated, on ebay (seller name = mtebob) and from our website