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Re: [T3] Nickle-chromium filament wire

On 10 Mar 2006 at 15:23, knowonelse@sbcglobal.net wrote:

> This appeared on the vintage bus list, but the expertise or knowledge 
> may lie here!

> To: <type2@type2.com>, <vintagebus@type2.com>
> From: "Ted Finesman" <tedebare@one.net>
> Hi Volks- a friend of mine is rebuilding fuel sending units for air-cooled
> VW's, buses included. We need to find a source for .002 nickel-chromium
> wire. I believe the proper resistance value of the filament to be 87.5 Ohms.
> Does anyone know if the resistance of n-c wire is the same for 30 ga? 

I've looked into this myself, but I don't have an answer yet. The 
resistance of our type 3 sensors is about 100 Ohms over a total 
length of about 1 foot.

Everyone, myself included, thinks of NiChrome wire for this kind of 
application, but it's not NiChrome, because NiChrome is almost 
impossible to solder to and this stuff solders easily. NiChrome is 
also quite hard, while this stull appears to be rather soft, since it 
is easy to stretch it by just pulling it between your fingers.

This application is actually not one for which NiChrome is 
particularly well suited. NiChrome is used in places where it is 
expected to run red hot, or hotter, without burning up. This 
application doesn't require the wire to be perceptably hotter than 

It's also hard to pin down because it appears to be a flat ribbon 
rather than a round wire. I can measure the thin dimension easily, 
but the width of this tiny ribbon is much harder to pin down. If I 
could measure it carefully enough to calculate its cross sectional 
area then it would be fairly easy to calculate its resistivity and 
then pick out the material from a table.

It's also possible that it started out as round wire, but that it has 
gotten worn, or deformed, into a flat shape.

I can't remember if I tried a magnet on it, but I know I found myself 
wondering if it could just be soft iron.

If someone has a good idea what this stuff actually is, I'd love to 
hear about it.

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org

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