PSN-L Email List Message

Subject: Re: Lehman
From: "David Saum" DSaum@............
Date: Fri, 15 Jun 2001 11:13:15 -0400


> From:    CapAAVSO@.......
> Date:    Thu, 14 Jun 2001 10:01:42 EDT
>
> A low friction pivot is still a friction pivot!!! A friction-free pivot
has
> been described consisting of a ring going around the lower pivot post with
a
> spring wire under tension in back of the post. The spring stores energy
and
> gives it back to provide a completely friction-free pivot.

 It is not clear to me why a "real" spring is more "friction-free" than a
ball
bearing rolling on a glass plate.  Any real spring will generate heat as it
bends
(from internal friction).  Without test data I do not see that either pivot
design
has inherently lower friction.  However, the ball bearing technique seems
to be simpler to build since it does not require a machine shop.

Ciao,

Dave

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Larry Cochrane <cochrane@..............>