Date:         Wed, 28 Nov 2001 17:48:07 EST
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Re: Torque Wench - calibration?
Comments: To: poll7356@uidaho.edu
Content-Type: text/plain; charset="US-ASCII"

Just thought I would chime in with my few centimes worth of comments here.

1. I always use a torque wrench -- whether I'm torqueing a bolt on the VWs,
Fords, SAABs, Porsches, MGs or Alfas --- or my $1.2 M Molecular Beam Epitaxy
system, or the $1.8 M Transmission Electron Microscope, or the Photoemission
system, or the microinstruments to be sent to Mars. At the Laboratory, when
assembling Spacecraft, assembly w/o a torque wrench is grounds for dismissal.

2. In all of the above cases, the bolt or nut is dressed with an antisieze
compound. For my home projects, I use the Permatex antisieze since it is
metallurgically compatible with the metals and chemically compatible with
possible coolant interactions. For external ultra high vacuum flange bolts I
use a MoS2 paste or silver plated SS bolts. For vacuum exposed surfaces, we
use the Ag-coated hardware.

I have often been told by the painless "experienced" machinist that they can
tighten by feel. Not once has that been verified by measurement. We have test
structures to measure applied force to 4 significant figures and test bolts
that shear at a specific applied torque. Many embarrassed machinists.

3. For home and lab use, I use clickers exclusively. I calibrate before each
major job against a Sears bar torque wrench. Just drive to click and note the
reading on the Bar wrench. A 3/8 Allen key drive socket one side and a 3/8
socket on the other. Or 10/10mm  sockets. Your choice.


Frank Grunthaner