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At the risk of huffs and sneers from 'out
there,' I think the whole business with proper torque values is a little
overblown. Most of the fasteners we use have no particular torque
specified, including hundreds of screws and AN3- and AN4- bolts. Sure, you
can look up proper torque values for them in handbooks, but let's face it, most
of us just go by feel. We've been putting things together with bolts and
screws all of our lives, and we learn what feels right for a given type of
fastener. Past experience probably includes more snapped bolts and
stripped threads, or fasteners that backed out or loosened, than we'd care to
think about. Each time that happens, we subconciously file away a little
lesson -- that was too tight, or too loose. For any given size bolt, we
have stored experience that tells us what feels right. It would be
interesting to have some experienced mechanics tighten a range of fasteners,
then go back and somehow measure the torque actually used. My guess
is that almost every one would be within a small margin of book
value.
OK, on critical stuff, like prop bolts and
engine mounts, we'll drag out the torque wrench and go by the book. The
rest of the time, you tighten till it feels right. Besides, unless you
have a good quality, calibrated torque wrench, and I mean recently calibrated,
it can be so far off that you'd be better off leaving it in the tool
box.
Jim Cameron
Legacy, N132X reserved
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