REGARDING Statics and Engineers
Whew! Thanks Jay and Greg for the Statics lecture. I was afraid I would have
to admit to being an engineer and give it myself. Its been 24 years since I sat
in a Freshman Statics class, but I remember not understanding the old
professor's explanation of the concept of moments until I realized it was just
like a torque wrench, with which I was already familiar.
So, a thumbnail summary:
1. Never use a torque wrench with a universal joint or a swivel socket or a
wobbley extension or a flexible-shaft extension.
2. Never use a torque wrench with a LATERAL offset extension between the socket
and the square drive of the T.W., such that the socket and square drive are no
longer coaxial. (I've never seen such a thing, but I imagine it could exist.)
3. Never use a crow foot socket with a T.W.
4. When using a standard (normal, straight, co-linear, co-axial) extension, use
your other hand to steady the T.W. at the square drive "head" end.
5. Don't put a long pipe on the handle to give you "more pulling power".
6. However, if you are small and need the extra leverage, we might allow an
exception to #5. You can break off the plastic handle on a beam-and-pointer
type T.W. and slide on a pipe, but only as far as the handle went, not
necessarily all the way up to the pointer scale. This may also be ok on certain
digital and dial types if the pipe only goes on as far as the hand grip, but
not for the clicker types that I've seen. If you're not sure what all that
means or if you're not sure you're doing it right, see #5 above. Or buy a
torque multiplier.
I looked in a McMaster-Carr industrial supply catalogue. They sell all kinds of
torque wrenches, even interchangeable-head and flex-head styles. Most are
claimed to be accurate to about 4%. Torque limiters, torque multipliers,
T-handle torque wrenches, even torque wrench testers @ about $1000. But no
lateral extensions.
Sure hope all this "torque talk" is actually helping somebody.
I, too, suffer from Engineer's Disease: Ask an engineer for the time, and he'll
tell you how to build a watch. ;-)
Rob Reilly, P.E.
Mechanical Design Engineer - Fermilab
BSIE - Bradley U '74
BSME - U of IL '79
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