Thread Fit specifications [6H, 6G, etc.]

[optics1]

I know my description says electrical but there is no choice for optics engineer, which is my discipline. So please forgive me if this post seems elementary.

I am familiar with the fit specifications for metric threads internal [5H, 6H, 7H] and external [4G, 6G, 8G] from loosest to tightest.

However what does that mean? What about the thread actually changes to tighten or loosen the fit?

Also, does this only apply to machined parts or can you specify thread fit for molded plastic as well?

I would appreciate any help, either answers or if someone can direct me to the applicable standard.

Thanks!
Peter H.
Sunex Inc.

 

[CoryPad]

The numbers and letters aren't abbreviations or measurements, they are just codes. What changes are the diameter measurements (minor, pitch, and major) of the internal and external threads. The thread tolerances apply to all metric threads that meet ISO 68-1 ISO general purpose screw threads -- Basic profile -- Part 1: Metric screw threads, whether they are metallic or plastic, machined, cast, molded, or forged. The specification that lists the tolerances is ISO 965-1 ISO general-purpose metric screw threads -- Tolerances -- Part 1: Principles and basic data .


Cory

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