[dsn_klr650] digest number 87
Posted: Wed May 03, 2000 2:37 pm
In a message dated 5/2/00 1:49:26 PM Canada Central Standard Time,
DSN_klr650@egroups.com writes:
>
As a former Metrologist, I would like to share a few tidbits of
knowledge/advice concerning the purchase and use of torque wrenches. Just to
help out ya know.
1) The cheaper the wrench, the less accurate it usually is. Most available
torque wrenches function on either a spring or transducer operation. The
cheaper wrenches use cheap material springs which are not very accurate and
don't usually last very long. Transducer wrenches are expensive and must be
adjusted/calibrated more often than spring style wrenches.
2) The most accurate area of usage for a torque wrench is in the center 50%
of the wrenches range. So you will want to choose a wrench that places your
highest usage area in the center of its total range.
3) Never, ever, store a torque wrench at any other value than zero, or the
lowest available setting. Doing so preloads the spring and will cause at the
worst complete failure, and at the least extreme inaccuracy.
4) If you are going to consistently use a torque wrench, it highly
recommended that you have it calibrated and adjusted at least every 24
months. Normally 12 months is a good cycle. Better safe than sorry.
5) Select your torque wrench (s) according to your needs. A 1/4" drive is
more appropriate for delicate jobs like top end engine work. A 3/8" drive is
more appropriate for your everyday run of the mill structural fasteners and
medium engine work. A 1/2" drive is the best selection for large jobs like
axle bolt torque
6) Most commercially (read public) available torque wrenches are accurate to
either +/-10% of reading, or +/-10% of full scale. Some better units can be
purchased from suppliers like Snap-On or MAC, etc. Just keep this in mind
when selecting a torque wrench.
7) Believe it or not, of the generally available torque wrenches, dial
indicating wrenches are more consistently accurate than the "click"/"snap"
type of wrench. Again, keep in mind when selecting wrenches.
Hope this helps everyone out. A low priced torque wrench does not exactly
mean a bargain torque wrench.
Jim Sherlock