On Sun, 23 Apr 2017 22:06:05 +0100, "Benderthe.evilrobot"
wrote:


"Emanuel Berg" wrote in message
...
I finally got the 1/2" torque wrench,
28-210 Nm, not even made in China, but in
Taiwan! Eh... I guess it depends who you ask if
that is China or not

It has a locking screw, a torque setting
handle, a scale (Nm as well as "FT-LB", some
English unit I take it?) - it also as a
locking lever on top just like an ordinary
ratchet, so it can go both ways, clockwise and
anti-clockwise.

The torques only work in the
clockwise direction. So if the
locking (ratchet) lever is set the other way,
it is just a ratchet, right? Well, in
the manual it says:

Note: Never use the torque wrench to undo
nuts, bolts or other fasteners as this will
damage the ratchet mechanism and the
calibrated settings.

So how does that add up? Is it only OK to use
the anti-clockwise pull to insert things, which
would require a left thread? (And it would be
just a long shaft, with the torque not
in effect.)

As for me, I don't plan using it for anything
but as a torque, because I have other, less
expensive ratchets and spanners to do the
everyday stuff. But of course, I'd like to know
what it means.

It also came with a certificate with data on
the calibration and in the manual it says it
should be recalibrated at least every
12 months.

Calibration is irrelevant if you don't follow the rules to the letter.

Most torque settings I've seen were for dry threads - any stray lubricant
and you might even twist the end off at the correct torque.


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Torque specs vary considerably by application. Some are given as
clean and dry, some are given as lubricated with oil - some are given
cold, and others hot. That said, I personally have never run across a
torque spec that was so "close to the edge" that torqing with "stray
lubrication" would cause immediate failure of the bolt by twisting off
the end.
However, that said, most of my wrenching has not been on bicycles but
on automobiles and agricultural and construction equipment which may
be slightly more "overengineered" or "overbuilt"
Also, some of the wrenching I have done on bicycles has revealed some
terribly poor quality materials (can anyone say "flying pigeon"?)

There have been tests done which indicate oiled threads do not affect
bolt tension and give the most consistent torque /tension results
(10W40 oil).Anti-sieze can increase the tension on a bolt by up to 71%
at the same measured torque.
Moly paste used as a lubricant was somewhere in betweeen - but
antiseize was non-linear in it;s results as the friction of the
threads did not increase with the tension on the bolt.

See http://benmlee.com/4runner/threads/threads.htm for the complete
results.

Even the difference between a cadmium plated bolt, a shiny zinc
plated bolt and a black oxide finished alloy bolt can be measured and
MAY be more significant than the difference between oiled and dry.
Also the existance or non-existance of a washer under the head of the
bolt or the nut can affect the tension on a bolt at a given torque -
or even the difference between a mild steel or a hard washer.

For a VERY accurate "torque spec", the rod bearing bolts, for
instance, on a high performance racing engine, are torqued to a
pre-determined stretch. The bolt is measured before installation, and
then is torqued until it measures a precise amount longer than the
initial measurement. This requires precision bolts - and the bolts
MUST NEVER BE RE-USED.
Under torquing (insufficient stretch) on these bolts will cause the
bolts to break in use.

I'm not aware of any "torque to yield" bolts in use on bicycles.