FWIW:
As Larry Hoy has pointed out the click type torque wrench
does need to be calibrated or it's calibration checked. I
am always leery of torque wrenches made overseas especially
when not branded by a reputable name. This is especially
true of the 'click' type.
On a beam type torque wrench, the modulus of the steel in
the beam and the accuracy of the scale determines the
accuracy of the unit. If the needle doesn't point to zero,
you can "calibrate" it by simply bending the needle. The
beam torque wrench has no moving parts. Only when using
very high torques and the difficulty in reading the scale
when pulling at 100 lbs does the beam wrench cause
problems. Then one needs a "helper" to either pull on the
wrench or read the scale.
I believe a 'click' torque wrench relys on a spring pressing
against a ball or pin which rides in a detent. As the ramps
into the detent wear from use, the wrench's callibration can
change. If the pin or ball wears, the release point can
also change. There are other "moving parts" that can wear.
Many beam torque wrenches have a significant error (plus or
minus) less than click torque wrenches.
Blake
/// or try http://www.team.net/cgi-bin/majorcool
/// Archives at http://www.team.net/archive
|