Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Fri, 28 Feb 2003 11:18:06 -0500
Message-ID: <redirect-2039843@logan.com>
From: Bob Pastusek <rpastusek@htii.com>
Subject: RE: [LML] proper toque values/calibration
In-reply-to: <list-2039810@logan.com>
Reply-to: rpastusek@htii.com
MIME-version: 1.0
Content-type: text/plain; charset=iso-8859-1
Content-transfer-encoding: 7BIT
Importance: Normal


...Anyway, one of the things suggested by my buddy was to calibrate the
torque
wrenches.  There are companies that do that but I was wondering if any one
out there has done it, what it costs and if anyone thinks it's worth it?

Dan Newland
ES #61

Dan,
Over the years I've had occasion to check my personal torque wrenches (Sears
and SnapOn brands) at Air Force test facilities (PMEL if you know the lingo)
and found that they were always within a few percent (less than 5% error) of
the set value. I'd say that if you have good tools and take care of them as
precision instruments, formal calibration is probably overkill for the kind
of work you're doing on building an ES. If you're working inside the engine,
I'd be a bit more careful about these things.

There's a simple test you can use to gain some confidence in your wrench:
Borrow a good quality torque wrench that's new or in good condition and use
a socket to "join" them together. Test one tool against the other. This is
no guarantee of accuracy--they could both be off--but if the results are
close and consistent across the torque range of the tools, I'd say you have
pretty good confidence that yours is OK.

I've never used a commercial service, but if they operate like the AF
facilities, you'll get a print out of the measured versus actual torque
values across the range of the tool. A nice record and confidence builder as
well.

No matter what, be sure to use a tool of the proper range. The typical
torque wrenches used in automotive work are almost useless when working the
AN3 to AN5 bolts we use extensively in aircraft construction.

Bob Pastusek