You're right, of course. What was I thinking! Obviously not the rigth answer, 
which I knew. My needle must have jumped a groove.

The remainder is new to me, however.

For both parts of that, the correction and the addition to my knowledge, many 
thanks!

Jim

On Wednesday 2004 January 28 18:29, Chimpsarecute wrote:
> > I wonder if the "C5" refers to a set or class of tolerances, then. The
>
> "4.8"
>
> > would refer to the diameter and thread spacing as normal for metric
> > fasteners.
> >
> > Jim
>
> No, the 4.8 refers to a fastener's property class, which in FFU screws
> would be the grade.   Each metric Class symbol consists of two numbers
> separated by a period. The first number is 1/100 of the nominal tensile
> strength in N/mm2 (newtons per square millimeter.  The second number is 10
> times the ratio of nominal yield stress to nominal tensile strength. For
> example, a Class 4.8 bolt has a nominal tensile strength of 400 N/mm2 and a
> nominal yield stress of 320 N/mm2 (8 times 400 divided by 10).
....


-- 
James R. Frysinger
Lifetime Certified Advanced Metrication Specialist
Senior Member, IEEE

http://www.cofc.edu/~frysingj
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