> One time in the distant past, I was using STP as an assembly lub., and
> stripped some threads.
That's the thing that puzzles me about this whole thread (no pun intended)
... 'Dry' is clearly an easily repeatable condition, and at least for most
stock fasteners, is the way the original torque specs were given. It seems
to me that 'Lubricated' is a hugely variable condition depending on just
what you use for a lubricant. Even "motor oil" may be highly variable since
it's being loaded far beyond the pressures it's normally used at, which
means that different oils may behave quite differently ... as the example
above shows.
So, why guess at how good your lubrication is under the conditions at hand,
and then call that more accurate than using the specified (and repeatable)
condition ?
Several have mentioned 'sticktion' ... I was taught to always hit the torque
target with the fastener still turning so that sticktion is not an issue.
If you stop close enough to final torque that it isn't still moving when you
hit final torque, you have to back off and do it again.
Clearly this doesn't apply to things like ARP fasteners, where torque
figures are given in combination with a specific lubricant ... as long as
you use that specific lubricant.
Randall
|