Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Sat, 01 Mar 2003 10:47:30 -0500
Message-ID: <redirect-2040705@logan.com>
From: "Gary Casey" <glcasey@adelphia.net>
Subject: torqued
MIME-Version: 1.0
Content-Type: text/plain;
	charset="Windows-1252"
Content-Transfer-Encoding: 7bit
Importance: Normal

The whole subject of bolt torques was interesting and brought up several
questions in my mind.  First, I was told (by Carsten, I think) that nuts
with nylon locks can't be reliably torqued as the resistance of the locking
feature is so variable.  Best to just tighten to a resistance and then a
little more (??).  And I note that on my ES small AN washers are supplied
for putting under a nut to be used over an epoxy/glass layup.  Surely any
normal bolt torque applied to the very small area of the washer will yield
the plastic, and in any event I assume the plastic will eventually creep,
causing a loss in clamping force.  On what I thought were critical
load-bearing joints I put an additional hardened steel SAE-type washer under
the AN washer to spread the load.  I was uncomfortable using the SAE washer
directly as the clearance around the bolt was considerably more than with
the AN washer.  For what I thought were "non-load-bearing" attachments I
used aluminum AN washers to save weight.  The rationale was that the
aluminum washer is still far stronger than the plastic underneath.  In most
cases I used all-metal locking nuts as they are less than half the weight of
the nylon locking nuts.  The cost of the weight savings assuming the nylon
locking nuts are free came out to about $40 a pound compared to my
self-imposed standard of $100/pound.

Anything wrong with my logic here?

Gary Casey
ES project, still in my garage in Thousand Oaks