M640 x 8 Diameters 1

[Tagger]

I am trying to find literature on large internal metric screw threads. Particularly M640 with a 8 pitch. Machinery's Handbook only goes up to 6 pitch for the tolerance grades 4 through 8.
What literature is out there that will provide the tolerances for a pitch 8, and the min/max for the major, minor, and pitch diameters.

 

[codeeng]

As far as I know there is no standard for metric screw thread pitches greater than 6mm (or 1/4" for UNC).

 

[diamondjim]

Check out Federal H28 Thread Standard.
Do you mean M64 instead of M640?

 

[Screwman]

Tagger,
The size that you want is outside of the scope of the published standard sizes. Luckily, ISO has a method to generate special thread sizes. Start out with ISO 68 to generate the basic thread dimensions and then use the formulas in ISO 965-1 to develop the tolerances for your thread. This should give you the information that you need to make your parts.

Dick