UNEF Thread Specification Geometry

jimbod20 · Oct 20, 2021

I'm looking through the UNEF thread specification standard and have a question.

I'll use .625-24 UNEF-3B for this discussion. The standard defines the minor diameter as .5800-.5869. The standard defines the pitch diameter as .6018-.5979. The standard defines the major diameter as .6250 minimum. I do want to make sure I don't end up with a thin wall in my threaded part. What dictates the maximum allowable major diameter?

I have the same basic question on the .625-24 UNEF-3A thread standard. What governs the minimum allowable minor diameter if the maximum allowable minor diameter .5739.

hydtools · Oct 20, 2021

The thread form as located by the pitch diameter.

Ted

jimbod20 · Oct 20, 2021

Thanks Ted.

Pud · Oct 20, 2021

The maximum diameter is limited by the thread angle from the max pitch diameter. That's why it's not toleranced in standards. Pitch diameter is the important bit.

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jimbod20 · Oct 22, 2021

Thanks Pud. I understand now.
I found some online calculators that are most helpful.

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UNEF Thread Specification Geometry

jimbod20

Aerospace

hydtools

Mechanical

jimbod20

Aerospace

Pud

Mechanical

jimbod20

Aerospace

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