Print Callout for a Special Thread - 1.173-18 UNS-3A Major Dia.

6

6 SIGMA

I have a print callout for a special thread. 1.173-18 UNS-3A. I need to know what the major diameter for this thread should be controlled to and, if you have a formula for calculating this, or can tell me where the information is located?

Thanks.
 

Stijloor

Leader
Super Moderator
I have a print callout for a special thread. 1.173-18 UNS-3A. I need to know what the major diameter for this thread should be controlled to and, if you have a formula for calculating this, or can tell me where the information is located?

Thanks.

Find a known thread for example 1.000-18 UNS-3A and you add .173" to to the values in the thread table.

Other suggestions anyone??
 
6

6 SIGMA

Thanks for the recommendation. I'll check into that option as well. One thing I did find in the Machinery's Handbook (25th edition) was this regarding designated UNS threads:

"Designated UNS Threads - UNS screw threads which have special combinations of diameter and pitch with tolerance to Unified formulation have the basic form designation set out first followed always by the limits of size" (Bold by me)

So, if I am reading this correctly, the designer should have stated the Major Diameter for his thread immediately after the specific thread callout.

Think I'll go back to them on this, too. Thanks.
 
S

stefanhg

Hi,

see the attached pictures
 

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