Fine vs Coarse Thread Question

Madman

Joined: Jan 19, 2001

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Not strictly automotive type Q but I thought this was the best place to ask.

If a thread is listed 8-40 would it be possible for the same 8-40 to be either UNC or UNF? Or in other words is the threads per inch irrelevant to a size being listed as fine or corse? Or would 8-40 only be one or the other?

TIA

Madman

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3:36p, 3/12/25

So for example

https://www.amazon.com/gp/product/B0CTWF7K64/ref=ewc_pr_img_2?smid=ATVPDKIKX0DER&psc=1

Would there be two versions for this? Fine and corse?

CEPhD

Joined: Sep 16, 2010

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4:34p, 3/12/25

No a diameter-thread pitch is only on one system. 8-32 would be UNC, 8-36 would be UNF. 8-40 would be UNS or Unified Special.

sts7049

Joined: Jul 2, 2004

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12:37a, 3/13/25

coarse

Roger350

Joined: Jul 23, 2001

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In reply to sts7049 • 6:27a, 3/13/25

sts7049 said:
coarse

V6

sts7049

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10:04a, 3/13/25

poke me, and i poke back!

Madman

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In reply to CEPhD • 12:06p, 3/13/25

CEPhD said:
No a diameter-thread pitch is only on one system. 8-32 would be UNC, 8-36 would be UNF. 8-40 would be UNS or Unified Special.

Excellent.

I appreciate the help.