Evolution of screw threads

Interesting but I am surprised it didn't mention the trivia that I have heard previously. Apparently knights were bolted into their suits of armour in some cases but the armour maker would make his own bolts individually. Apparently some nuts will not fit other bolts even in the same suit and almost certainly not in other suits.

Small sizes of Whitworth and UNC are almost interchangeable even though the angle differs by 5 degrees. Pitch is the same up to 2 inches and other dimensions quite similar.
 
vyv_cox said:
Interesting but I am surprised it didn't mention the trivia that I have heard previously. Apparently knights were bolted into their suits of armour in some cases but the armour maker would make his own bolts individually. Apparently some nuts will not fit other bolts even in the same suit and almost certainly not in other suits.

Small sizes of Whitworth and UNC are almost interchangeable even though the angle differs by 5 degrees. Pitch is the same up to 2 inches and other dimensions quite similar.
Click to expand...

……………and UNF and metric have the same thread form.
 
vyv_cox said:
Interesting but I am surprised it didn't mention the trivia that I have heard previously. Apparently knights were bolted into their suits of armour in some cases but the armour maker would make his own bolts individually. Apparently some nuts will not fit other bolts even in the same suit and almost certainly not in other suits.

Small sizes of Whitworth and UNC are almost interchangeable even though the angle differs by 5 degrees. Pitch is the same up to 2 inches and other dimensions quite similar.
Click to expand...

Well you learn something new everyday: I didn't know that was a problem with suits of armour!

I was aware that some US screw threads were similar to British threads but not that it was UNC and Whitworth.

Apparently the world is switching over to metric with only the US and Canada staying (in the short term) with the Unified screw thread system.

https://www.threadcheck.com/technical-documents/thread-systems.pdf
 
halcyon said:
We went metric in the 1970's, the USA 1887, or around then, never got implemented.[/QUOTE]

The Hubble telescope would have been a lot cheaper if it had been.

If I remember correctly, in the UK metric was adopted in dribs and drabs from about the mid-60s. For money it was Feb '71.

Imperial's a whimsical old system. The rod (not the one you'd spare) was described as the length of the left feet of 16 men lined up heel to toe as they emerged from church. Measuring for hall carpets must have become pretty crowded.
Click to expand...
 
macd said:
halcyon said:
We went metric in the 1970's, the USA 1887, or around then, never got implemented.[/QUOTE]

The Hubble telescope would have been a lot cheaper if it had been.

If I remember correctly, in the UK metric was adopted in dribs and drabs from about the mid-60s. For money it was Feb '71.

Imperial's a whimsical old system. The rod (not the one you'd spare) was described as the length of the left feet of 16 men lined up heel to toe as they emerged from church. Measuring for hall carpets must have become pretty crowded.
Click to expand...

We went metric twice, once to the old system, then to the SI system once we had sorted out the first system, the Germans just changed the new system to match the old one and carried on with no changers.

Another reason for engineering failure.

Brian
Click to expand...
 
The most interesting place to go for some of this stuff is the Long Shop museum in Leiston in Suffolk. It was where Garrett built traction engines and boasts the first "production line" system, and they made all their parts in that way to suit that method, IIRC around the 1840's 1850's?
 
The source of the difference is not Imperial vs. Metric, but that as the industrial revolution took off (with Britain in a leading position) different firms each had their own standards. (These were made possible by machine produced threads, an advance on every nut and bolt being hand made and different, as per the armour example above.) Those firms who dominated certain sectors of industry, and/or had particularly useful standards, had their standards adopted by other firms in particular fields or applications.

Only later did different nations (or groups of nations) establish national (or international) standards to try to regularise and limit the range of threads/dimensions, some of which were based on, or influenced by, the particular area's industry leaders' standards. None of these national or international standards has (yet?) become universal, I imagine largely due to inertia, but also politics and the need for variations of threads for various specialist purposes.
 
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vyv_cox said:
Of course you are right. It's been a long time since I worked with them.
Click to expand...

Sadly, a lot of these are etched into my brain!

I spent so much time in my youth searching for metric bolts for a "foreign" motorbike. not easy at the time. Then came a time when I struggled to find UNC/UNF and BSW/BSF. Then we got google and e-bay!

Maplin used to be good for BA sizes, but these were all deleted from their catalogue a long time ago. I was pleased to buy a lot of clearance stock at 5p a pack.
 
An interesting thread is Brass Thread, (sometimes improperly called a standard). A fine thread, 26tpi through the range, stemming, I believe, from when brassware was hand-turned, and the turner could traverse the screwcutting tool at a constant rate irrespective of the diameter.
Re. metrication, I once owned a pre-war Morris car which had metric fine threaded bolts with imperial-sized hexagons.
 
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earlybird said:
An interesting thread is Brass Thread, (sometimes improperly called a standard). A fine thread, 26tpi through the range, stemming, I believe, from when brassware was hand-turned, and the turner could traverse the screwcutting tool at a constant rate irrespective of the diameter.
Click to expand...

ISTR "Cycle Thread" is also a constant 26tpi over a range of sizes. Good where you need a fine thread on a large diameter, like bottom brackets.
 
LittleSister said:
The source of the difference is not Imperial vs. Metric, but that as the industrial revolution took off (with Britain in a leading position) different firms each had their own standards. (These were made possible by machine produced threads, an advance on every nut and bolt being hand made and different, as per the armour example above.) Those firms who dominated certain sectors of industry, and/or had particularly useful standards, had their standards adopted by other firms in particular fields or applications.

Only later did different nations (or groups of nations) establish national (or international) standards to try to regularise and limit the range of threads/dimensions, some of which were based on, or influenced by, the particular area's industry leaders' standards. None of these national or international standards has (yet?) become universal, I imagine largely due to inertia, but also politics and the need for variations of threads for various specialist purposes.
Click to expand...

Joseph Whitworth produced the first National Standard thread BSW in 1841.

Brian
 
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