Torque wrench

Shawn wrote:
Phil, Squid-in-Training wrote:
I would say extra long allen wrenches (2.5mm - 6mm) are a recipe
for a twisted wrench... bolts those sizes never yield, and 8-10mm
wrenches torque down no problem.


Never yield? Never's a long time. I've seen plenty break, right
at the base of the head. And not *all* my fault. :-)
Usually though, what I've seen is that either the bolt head or the
wrench strips. Maybe it's the bolt/wrench tolerance, but to me it
seems like 5mm bolts can snap or strip easily, but 8 mm can handle
more torque than I can give. Go figger.


It's the effective force at each facet of the wrench. If you give
1Nm of torque on a 1m wrench, the flats of a 5mm wrench will
experience a little less than 200N at the wrench/bolt interface,
whereas the flats of a 8mm wrench will experience only a little less
than 125N. That's a reduction of almost 40% with only a 3mm size
difference.

That 'splains it then, thanks.

I've broken cheap 5s that consist of metal bonded together with a
seam running down the middle... a poor excuse for a real tool.
Forged tools are the only way to go.

What kinds of bolt heads have you snapped, and on what specific part?

Brake cable binder bolts (SunTour road as well as cheapy ones in the
shops I've worked in).

Shawn

So when the heck did this place turn into rec.bicycles.tech???!!

Mike