I'm just trying to sort of the seemingly simple matter of replacing some imperial studs. They're 5/16" and have a thread pitch of 24tpi. You'd really think that be enough wouldn't you but oh no, I now have to try and work out whether they're BSF, BSW, UNF or Cycle thread ... all measure up exactly the same but there are small yet important differences that prevent any mixing or matching ... fantastic

Metric is certainly simpler, I still measure in inches and mil though
Sorting my tool shed next weekend but the box of A/f, whitworth etc spanners
Will be staying......because you never know

Yep, a complete nightmare of "standards" - I wonder where the bike industry got that idea from

On the farm there was this big barrel of old nuts and bolts. We were having a periodic clear out and suggested to my dad that we'd weigh in the barrel - there was probably quarter of a tonne of (rusting) metal in there. "No it will come in useful" he says. I pick up a bolt at random. "So what are we going to use a 2 5/16" Whitworth threaded bolt for?" "Well we might need it", "But everything on the bloody farm is METRIC!"

Shortly after he died my brother weighed in the barrel.

24tpi = 5/16 UNF. 5/16 BSF is 22tpi. Whitworth 20 and BSC 26. Simples!
Imperial threads are far superior to metric threads...

Thread gauge?

Car boot sales can be your friend, old taps are handy for identifying threads, or what you'll 'get away with'..
Only prob is that they'll spend the majority of their life in a draw..

Thread gauge?

Thread gauge will only give you the pitch Jase not the thread form.

24tpi = 5/16 UNF. 5/16 BSF is 22tpi. Whitworth 20 and BSC 26. Simples!

I thought that Phil but I can get Whitworth in 24tpi and I'm thinking (but could be wrong) that UNF would be unlikely?

This thread makes me think of when I was an apprentice, and the mechanical instructors tried to give us electrical and instrument apprentices an introduction to how to use a Zeus Book. I still have my (unopened for 30 years) copy somewhere. I think that I only ever used it to pass that test.

Ah whitworth, I cut my teeth on Gardner 180’s , with those strange size spanner’s

https://www.engineersedge.com/hardware/ ... -chart.htm
24tpi BSW is a 3/16" shaft?
BSW (and BSF) threads are 55 degrees and UNF is 60 so a thread guage should show the differences. I must admit I tend to work this out by dint of having lots of known thread nuts and bolts and then using trial and error....

I still use a lot of imperial stuff, hydraulics and now American lifting gear is still AF. In addition to the usual imperial threads you also get some real oddity’s such as ‘railway’ threads which really leave you scratching your head. I used to have something similar to a zeus book with all these weird things in.

real oddity’s such as ‘railway’ threads

I once rebuilt an obscure supercharger which was held together with 'American Fire Fighters' threaded bolts

BigdummySteve wrote: ↑Tue Aug 25, 2020 8:46 am real oddity’s such as ‘railway’ threads which really leave you scratching your head.

Just don't . I've got an inch-deep groove in the top of my head.

Very interesting 'thread' this one is .

Donkey's years ago when I worked in site investigation we had a driller seriously injured by a hose that came loose from the air compressor for his drilling bicycle. IIRC the cause (exacerbated by no / crap whip-restraints) was that the threaded fittings on the compressor connection and the hose were close (i.e. enough to install and convince the guys it was OK to use), but different threads (possibly metric and imperial). The guy survived but was badly hurt and spent some time in ICU.

Slightly weird thing to go into I guess but illustrates the point that getting properly matched fittings can be a big deal.

RIP wrote: ↑Tue Aug 25, 2020 9:06 am

BigdummySteve wrote: ↑Tue Aug 25, 2020 8:46 am real oddity’s such as ‘railway’ threads which really leave you scratching your head.

Just don't . I've got an inch-deep groove in the top of my head.

Very interesting 'thread' this one is .

It get even more convoluted when you get into lathe cut threads, diffrent thread angles, multi start etc, its enough to spiral into dispair

IIRC from the documentry the mechanic responsible for this near tragedy had trudged his way across the yard to a dimly lit shed, shoved his hand in a box of bolts and thought 'aah they look the same'!
Look at the investigation.
https://en.m.wikipedia.org/wiki/British ... light_5390

HUX wrote: ↑Tue Aug 25, 2020 1:49 pm IIRC from the documentry the mechanic responsible for this near tragedy had trudged his way across the yard to a dimly lit shed, shoved his hand in a box of bolts and thought 'aah they look the same'!
Look at the investigation.
https://en.m.wikipedia.org/wiki/British ... light_5390

Blimey

This may be a case of the "truth not getting in the way of a good story" but I was told this one by my uncle-in-law, an ex-aerospace engineer.

He was working for one of the smaller passenger / private / executive jet firms and based in the US. They sourced a lot of parts from various sub-contractors and factories in Europe. An issue arose in QC/QA where the cockpit screens were failing at too frequent a rate. So he came over to visit the manufacturers and testing facility. Apparently the failures were occurring in the test to check they were "good" to withstand a bird strike. The test was apparently to fire a bird carcass using some sort of pneumatic "canon" at a screen and see if it survived or was damaged. On closer inspection it was found that, due to a shortage of suitable carcasses, the facility had been using readily available turkeys.

Shame they weren't defrosting them before they got loaded in the canon and fired!

Whether it's true or not it usually raises a smile

Yep, heard that one with respect to testing of Eurostar trains windscreens - which would suggest a level of apocryphallity (is that a word? it is now) about the story . Still hilarious though!

I originally heard that one in relation to testing concord's windscreen umpteeen years ago.

Like I said, never let the truth .....

I remember my Dad (ex aeronautical engineer) going on about that BA flight incident. Getting bolt threads and lengths mixed up was not uncommon...... I think all screens are fitted from the inside now. In the early days of airliners it was the doors that blew out, hence the fancy system they have now so that the doors seal from the inside.

There are lots of nearly fit thread crossovers and it doesn't help that I have boxes of all imperial types as well as standard metric and metric fine. I have a full set of thread gauges.... Handy though sometimes. On a trip south on my Ariel one of the gearbox stud nuts went awol (9/16 BSC) and a 9/16 UNF nut supplied by a campsite owner off his triumph herald box of bits fitted perfectly.

And whilst we are on the subject, threads are further proof that bicycles are rubbish - inner chainring bolts being the classic - a horribly fine thread into a soft material just so its the same as the ones which fit middle and outers. M5 bolts on bottle, rack and mudguard eyes which are too coarse so constantly shake loose; then there are crank puller threads - fine for steel cranks but they weren't changed when cranks all went to alloy.....And as for BB threads......