Custom Thread Callout, no P.D.

[Hugh Man]

Hi all,

I'm looking for advice on how to deal with a customer's thread callout on their print. It is an internal dual-lead 60° v thread, but the concern is that they define the nominal and tolerance for major, minor and thread pitch, but there is no pitch diameter callout. My concern is the internal major diameter with a +.002/-.000" tolerance. After reading a bit of ASME B1.1 and researching online it seems the maximum major diameter of an internal thread is always undefined because it just serves as clearance anyway with the mating part.

My question is, before I go back to the customer with this issue, has anyone had to deal with a thread defined this way before and if so how did you inspect it? I imagine designing go/nogo thread plug gauges with 30° flanks for clearance on the part, but I can't find any examples online of this having been done. Thank you.

Also, I have seen the mating screw thread and it has a 60° v thread with a MMC major diameter that would clear the MMC major diameter of the internal thread, though this probably sounds obvious.

 

[CheckerHater]

Without Pitch diameter the profile of your thread is free to float wrt Major / Minor diameters, so thread definition is incomplete (providing this is custom thread)
Are there any clues as additional dimensions, or reference to standard(s)?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[Hugh Man]

Hi CheckerHater,

unfortunately no, the remaining dimensions are independent of the thread form and the only reference to a standard is the ASME y14.5 for GD&T interpretation.