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Subject: Re: A test curtain rod bracket/s vertical
From: "Charles R. Patton" charles.r.patton@........
Date: Wed, 03 Sep 2008 16:21:53 -0700

Some years ago I got some Elinvar from Hamilton Precision metals.

A quick search of the PSN discussions found probably the best summary by 
Karl Cunningham 20 Oct 1998.-----
There are several alloys that exhibit near zero temperature coefficient of
modulus of elasticity, at least over the range near room temperature.
According to the Machinery Handbook, 22rd edition, they are:

Elinvar (Trade name of Society Anon. de Commentry Fourchambault et
Decazeville, Paris, France) -- The first constant-modulus alloy used for
hairsprings in watches. Variations are known by Elinvar Extra, Durinval,
Modulvar, and Nivarox.

Ni-Span C (Trade name of International Nickel) -- Very popular
constant-modulus alloy. Useful up to 60K - 80K psi stress.

Iso-Elastic (Trade name of John Chatillon & Sons) -- Useful to 40K to 60K
psi. Used in dynamometers, instruments, and food-weighing scales.

Elgiloy (Trade name of Elgin National Watch Co) -- Also known as 8J Alloy,
Durapower, and Cobenium. NON-MAGNETIC alloy useful up to 75K psi stress.
Used in watches and instrument springs.

Dynavar (Trade name of Hamilton Watch Co) -- Also NON-MAGNETIC. Similar
characteristics and uses as Elgiloy.

Charles Patton

Gary Lindgren wrote:
> Hi Chris,
> Thank you for the re-education on the temperature stable metals. I 
> remember using Invar back in my microwave vacuum tube days. Invar and 
> similar metals hardly expand with increasing temperature. They are 
> very different. Iím looking into Ni-SpanC 902. Just to see whatís 
> available.
> Gary


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