UH threads ?

[Shannow]

Never come across a need to be specifying them before, but now do.

Correct me if I'm wrong, but they are a 60 degree UNF form, on an 8tpi standard regardless of size ?

I know the poms use a BSF, but with a 6tpi standard from 1" dia to 5-1/2" dia, looks like GE did the same.

 

[XS650]

UH doesn't sound right. Is it UN - Unified Constant Pitch Threads.

There are several constant pitch threads in that standard. 8 tpi regardless of diameter is one of them. They do use the standard 60deg thread form as used in UNC and UNF.

They should be defined in Machinery's Handbook. PM me if you need a copy of the pages.

 

[Shannow]

XS650, definitely UH. (I can post photos of the taps)

 

[Shannow]

and getting some made from X20CrMoWV12.1