Cycle Thread MIA

[Stephen Hill]

Today I opened up my Machinery's Handbook and was surprised to find no reference whatsoever to the CEI (BSC) thread series. I found Whitworth coarse and fine, and BA, but nothing at all on cycle threads.

I have a 1978 edition, which was around the time the handbook incorporated a lot of info on metric threads. Maybe some old thread series were punted out at the same time?

Anybody know how far back you have to go in earlier editions of the Machinery's Handbook to find this info?

Stephen Hill

 

[Rohan]

No idea about the Machinery Handbook, but Cycle Thread specs are readily available online.
e.g.
http://www.motalia.com/Html/Charts/cycle_chart.html

Note that there are fine and coarse versions of this thread, and quite a few stray sizes along the way..

BTW, it is not strictly correct to say there are fine and coarse Whitworth threads.
Whitworth is the early coarse version - and standardised quite a range of assorted English thread types.
BSF came quite a bit later - using British Standard (BS) type head sizes and angles and diams.
BSW likewise came later then too, when much was standardised...

Yes we know that murricans like to lump all this together as whitworth.....

 

[Stephen Hill]

Not to put too fine a point on this thread......, but:

"The B.S.W is the Coarse Thread series and the B.S.F is the Fine Thread series of British Standard 84:1956 - Parallel Screw Threads of Whitworth Form.

Looks like the Machinery's Handbook lumps them together as Whitworth as well.

Stephen

 

[Rohan]

This is where murricans differ on understanding threading systems. !
That is more accurate than what you initially said....
BSW and BSF are different animals than 'Whitworth'

So, BA has (mostly) metric derived type threads.
But if you ask your local bolt supplier for 'metric' bolts to fit your Smiths or Lucas parts,
he'll say "surely you want BA."

Same as if you ask for 'Whitworth bolts' to fit your MG or Norton Atlas,
he'll say "surely you want BSF ".

AND Note that BSW and Whitworth are not quite the same thing.
Standardised is the operative word, and difference.

 

[Nortoniggy]

I have my father's 11th edition Machinery's Handbook, published in 1943, and there is no reference to Cycle thread in that edition either. A glaring omission I'd say. There are quite a few threads that I'd not heard of before.

Ian

 

[Peter R]

But if you ask your local bolt supplier for 'metric' bolts to fit your Smiths or Lucas parts,
he'll say "surely you want BA."

If I ask this question to my local bolt supplier, all I get is blank stares. :shock:

 

[Rohan]

If I ask this question to my local bolt supplier, all I get is blank stares. :shock:

Ha ha, probably true at most of the local suppliers here too these days.

Sadly, thats becoming mostly true too even for once common Whitworth or BSW.
BSF is not too widely stocked either.
At least they know what it is - or was...

 

[Madnorton]

Sadly they all get lumped together theses days, cycle - from the days of penny farthings I'd imagine, rationalised to cei was about 1964 and BSC shortly after I do believe, all various standards through time. Whit form gets used a lot these days to describe the angle of many threads which on its own is not how it should be used.

 

[JimNH]

Murricans are voting for Trump; the rest of us know the difference.

 

[gripper]

Machinery Handbook is an American publication. While most Cycle threads are 26 TPI the thread form is 60 degrees. BSF and Whitworth are 55 and BA 47.5 degrees.

 

[Stephen Hill]

Most cycle threads on our Nortons are 26 TPI.
But if you check out the full size range, only about a third of them are 26 TPI:

http://www.oldengine.org/members/diesel ... cycle1.htm

Stephen Hill

 

[Rohan]

And brass thread is 26tpi but 55 degrees.
Not sure if its a BS (British Standard) or not...

My old Triumph belt driver project is nearly all 30 tpi fasteners.
An early Indian is nearly all 24 tpi fasteners.
An early Harley is nearly all 28 tpi.
* from memory

Try buying those in Woolworths or NAPA if you really need one...

The benefits of standardisation just cannot be over emphasised.
Be it BSW or UNC or BSF or UNF, or ISO Metric for that matter, etc.