18
MARINE TECHNICIAN TODAY | SUMMER 2013
2. Make sure your direction lever is fully
engaged on your torque wrench.
3. Make sure you grasp the handle firmly in the center
of the grip handle while applying torque and try to use this
position for every fastener.
4. Always pull on every fastener using a firm even motion.
For the rest of the story I contacted Keith Chauvie, Director of Quality
for Cornerstone Metrology Services Inc. Mr. Chauvie is one of the
leaders in the field of accurate measurements and services and is an
ISO / IEC 17025 Accredited Calibration Laboratory in Van Nuys, CA
since 1983. Phone: 818.902.9551,
Cornerstone Metrology has an extensive list of companies, clients
and independent shops that rely on their services of measurements,
calibrations, recalibrations and advice, among other services
provided. For more information go to their website listed above or
give them a call.
Keith Chauvie emphasized in our conversation that the operator can
be the worst enemy or the best asset regarding accuracy while using
a torque wrench. When using a digital torque wrench, placing your
hand in different positions can or will change the torque values. Mr.
Chauvie points out that the most accurate torque wrench to use is a
dial indicator type because they have a wider, stronger front base and
are dial calibrated for elastation (bolt stretch). He also said if you drop
a dial indicator torque wrench it absolutely needs to be checked &
recalibrated. Cornerstone Metrology can provide these services.
Next he pointed out that a dial indicator torque wrench can be superior
to a digital or click type because you can watch the needle move to
see if it jumps, especially as you approach your specified torque value.
If the needle jumps, you have a problem that can indicate that your
fastener could be too long, your fastener has a thread problem, or a
bolt or stud may be excessively stretched. A click type or digital type
torque wrench will never show this error. Cornerstone Metrology
recommends never using thread chasers to clean threads unless
absolutely needed, they can cause tearing of the threads. Mr. Chauvie
recommends using wire brushes and WD 40 or diesel fuel to clean
threads and bolt holes. He also recommends a small dab of anti-seize
with graphite on the threads before torqueing nuts and or bolts. Look
for part two of my discussion on torque wrenches in my column “The
Performance Corner” in the next edition of AMTECH’s newsletter,
Marine Technician Today.
“Torque wrenches shouldn’t be
viewed as just another wrench in
the tool box. They are precession
measuring tools and need to be
appropriately cared for.”
.
John
Mosetti
