Watanabe thread size?

[Ron Nossaman]

> Anyone know what threads the Watanabe tip receives?
> 
> The stud onto which the tip screws measures 9.49 mm X 0.85 pitch in
> metric.  I'm guessing that's almost certainly *supposed* to be 9.5 mm.
> 
> 9.5 mm is almost 3/8" -- just 0.0013" shy of it, in fact.  A standard
> 3/8" with 30 threads per inch corresponds exactly to the stud
> threads...except for the very slight difference in diameter.
> 
> So I'm thinking the 3/8" will work fine.  The tip has enough play in
> it that it should screw on without any problem.
> 
> Anyone know offhand?
> 
> Thanks,
> 
> JF

John, you're an engineer type. Given the thermal expansion 
coefficient of steel, how many degrees Fahrenheit change does 
it take to make a 0.0013" change in the ID of the tip threads? 
Is it over 10°?
Ron N