Any screw thread experts?

[geeman237]

I was nerding out on a copy of the Standard Triumph Hardware Catalogue and came across references to screw threads that were distinctly separated and I don't know the difference, so perhaps someone here knows.

The catalogue specified for example, 1/4" NF and 1/4 UNF as two distinct threads. I know most Triumphs of the 1960's on used UNF which is an American standard. But what is 1/4" NF or NC as a thread type, what standard is it known as? The catalogues also explicitly identified BSF, BA and Whitworth in its descriptions. I get the impression that 1/4" NF is not the same as 1/4" BSF?

This should be a link to a pdf of the catalogue. Page 4 of the catalogue shows what I mean.

https://www.google.com/url?sa=t&source=web&amp...

Anyone able to enlighten me?

[Mercdriver]

Buy a set of Zeus charts, all the major thread sizes metric and imperial are listed, pitches, clearance holes and tapping hole sizes a wealth of information.

[Big Al.]

Mercdriver said:

Buy a set of Zeus charts, all the major thread sizes metric and imperial are listed, pitches, clearance holes and tapping hole sizes a wealth of information.

Excellent idea.

IIRC Unified threads all have a 60 Deg thread angle, whilst BSF and BSW have a 55 Deg thread angle, The threads won't interscrew with each other.

I'm not too sure regarding the NF (national Fine) and NC (national Corse) threads, so I'll check that in my Zeus book tomorrow, if I can throw any light on the subject I'll report back.

Also have a browse through this :-

https://www.google.com/search?q=thread+size+chart&...

Edited by Big Al. on Tuesday 25th June 21:41