Looking for resistive wire with shellac coating

[Stumpy]

Small diameter NiChrome with insulation. Do I have to make it myself?

 

[Stumpy]

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?

 

[Pooh Bear]

LOL ! It works too. ;~)

Graham

 

[Yukio YANO]

Small diameter NiChrome with insulation. Do I have to make it myself?

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

Yukio YANO

 

[Stumpy]

They've got the right wire, but its not insulated. Magnet wire is coated
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.

 

[Pooh Bear]

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

 

[Stumpy]

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.

 

[Stumpy]

---
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!

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.

 

[Yukio YANO]

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

 

[Stumpy]

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.

http://www.omega-wire.com/tables.htm

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.

 

[[email protected]]

We sell small quantities of resistance wire, both bare and insulated,
on ebay (seller name = mtebob) and from our website www.hotnichrome.com
We have many gauges and alloys.