Straight Thread Inspection Questions 1

[Inspection Girl]

Are the Pitch Diameters of thread for a 2B and 3B the same?

 

[XL83NL]

2B and 3B of what? Which thread standard?

Huub

 

Not quite exactly. The designators you quote are classes of fit for UNC fasteners.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[3DDave]

I believe the nominal pitch diameters are the same, but the variation from the nominal is larger for the class 2 than for class 3. I think the effect of this is seen in the manufacture by makers shifting to a smaller diameter for class 2 to ensure it fits in the range of the variation their equipment makes.

In the case of external threads the nominal is the maximum. For internal threads it's the minimum.

 

[tbuelna]

Refer to ANSI B1.1 or FED-STD-H28/2.

 

Or refer to Machinery's Handbook, any edition.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."