## PSN-L Email List Message

Subject: Re: Questions of the Temperature stability of the rolling pivot
From: meredith lamb paleoartifact@.........
Date: Fri, 24 Jul 2009 22:29:57 -0600

```HI Chris,

Will honor your recommendations; to see just how big a range of temperature
versus positional drift it goes exhibit.

Interesting on the short period v/s low drift sentence.  It sounds like it
would be a insignificant problem with a reasonable
placement and cover to begin with....for this 3s unit.  Thats good news.

Take care, Meredith

On Fri, Jul 24, 2009 at 9:51 PM,  wrote:

>  In a message dated 24/07/2009, paleoartifact@......... writes:
>
> If....it is significantly "self adjusting", it would then seem to be a
> approach that "could" somewhat eliminate that normal temperature problem and
> open up the use of such similar steel and simple construction continued test
> use.
>
> Hi there,
>
>     I suggest that you fit the end of the boom with a vertical position
> marker and a vertical ruler and also check the instrument temperature when
> checking the position. There is NO substitute for direct measurements! You
> don't see large position variations for periods under about 3 seconds.
>
>     The temperature coefficient of Youngs modulus is 2.4 x 10^-4 / C Deg
> for steel. The expansion coeffieicnt is about 12 x 10^-6 / C Deg
>
>     Regards,
>
>     Chris Chapman
>
HI Chris,
=A0
Will honor your recommendations; to see just how big a range of temper=
ature versus positional=A0drift it goes exhibit.
=A0
Interesting on the short period v/s low drift sentence.=A0 It sounds l=
ike it would be a=A0insignificant problem with a reasonable
placement and cover to begin with....for this 3s unit.=A0 Thats good n=
ews.
=A0
Take care, Meredith=A0=A0
On Fri, Jul 24, 2009 at 9:51 PM, <ChrisAtUpw@.......> wrote:

In a message dated 24/07/2009, paleoartifact@......... writes:

If....it is significantly "self adjusting", it would then se=
em to be a approach that "could"=A0somewhat eliminate that normal=
temperature problem and open up the use of such=A0similar steel and simple=
=A0construction=A0continued test use.

Hi there,
=A0
=A0=A0=A0=A0I suggest that you fit the end of the boom with a vertical=
position marker and a vertical ruler and also check the instrument tempera=
ture when checking the position. There is NO substitute for direct measurem=
ents! You don't see large position variations for periods under about 3=
seconds.

=A0
=A0=A0=A0=A0The temperature coefficient of Youngs modulus is 2.4 x 10^=
-4 / C Deg for steel. The expansion coeffieicnt is about 12 x 10^-6 / C Deg=
=A0
=A0
=A0=A0=A0=A0Regards,
=A0
=A0=A0=A0=A0Chris Chapman
```