Thread Gauges

[Chris TickTockParticipant @christicktock]

Hi I have bought a set of 3 thread gauges, the multi leaf variety.. One I do not understand. It is for measuring Whitworth and ranges from 62G-4g. eg one leaf has 60G1/16 marked on it. I understand whirorth have a parallel pipe thread that is G but are these gauges suitable for more prosaic bolts etc?

Regards

Chris

[Chris TickTockParticipant @christicktock]

[JasonBModerator @jasonb]

Posted by Chris TickTock on 28/08/2019 13:11:33:

60G1/16 marked on it.

A quick look at any Whitworth thread chart should give you a clue, look at the top line of this chart

[Chris TickTockParticipant @christicktock]

Posted by JasonB on 28/08/2019 13:27:34:

Posted by Chris TickTock on 28/08/2019 13:11:33:

60G1/16 marked on it.

A quick look at any Whitworth thread chart should give you a clue, look at the top line of this chart

Thanks Jason so it actually correlates to TPI but then why the G?

Chris

[BazyleParticipant @bazyle]

There was another thread questioning this last year. I think the G was just for 'gauge' or something German. It isn't a different size. Some leaves on mine have the G and some don't, probably gets left off as unnecessary when the die is updated.

[Howard LewisParticipant @howardlewis46836]

These Whitworth thread gauges will allow you to confirm the thread as a Whit form thread, (55 degrees as opposed to the 60 degree form of American National, Unified or Metric ).

The first number indicates the threads per inch, and the second the diameter in Inches, or fraction thereof, FOR BSW THREADS.

Often, in USA, threads will be designated in a similar manner, such as 1/4 – 20, although this will be likely to to refer to 1/4 UNC rather than 1/4 BSW.

Since the BSW and BSF forms are the same, these gauges can be used to check the pitch of BSF or BSP threads; although 20 tpi will be for 3/8 BSF, as well as for 1/4 BSW

The only pitches likely used on BSP (British Standard Pipe ) threads will be 28, 19, 14, or 11 tpi

American pipe (NTP , NSP etc ) threads will not be the same pitch as BSP, usually differing slightly, ( 1 tpi or so different ) and will be 60 degree form.

HTH

Howard

Edited By Howard Lewis on 28/08/2019 13:53:03

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Bazyle on 28/08/2019 13:47:51:

There was another thread questioning this last year. I think the G was just for 'gauge' or something German.

.

**LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=107919

[Chris TickTockParticipant @christicktock]

Posted by Howard Lewis on 28/08/2019 13:51:42:

These Whitworth thread gauges will allow you to confirm the thread as a Whit form thread, (55 degrees as opposed to the 60 degree form of American National, Unified or Metric ).

The first number indicates the threads per inch, and the second the diameter in Inches, or fraction thereof, FOR BSW THREADS.

Often, in USA, threads will be designated in a similar manner, such as 1/4 – 20, although this will be likely to to refer to 1/4 UNC rather than 1/4 BSW.

Since the BSW and BSF forms are the same, these gauges can be used to check the pitch of BSF or BSP threads; although 20 tpi will be for 3/8 BSF, as well as for 1/4 BSW

The only pitches likely used on BSP (British Standard Pipe ) threads will be 28, 19, 14, or 11 tpi

American pipe (NTP , NSP etc ) threads will not be the same pitch as BSP, usually differing slightly, ( 1 tpi or so different ) and will be 60 degree form.

HTH

Howard

Edited By Howard Lewis on 28/08/2019 13:53:03

OK I think I am getting thos 'form' thing in relation to BSW and BSF you mean the waves are the same angle and shape but on the finer BSF the heights and lows are less. Therefore you would distinguish between the 2 threads by the profiles magnitude on the bolt or screw.

Chris

[larry phelan 1Participant @larryphelan1]

I use my gauges all the time in order to check some of the oddball threads I come across from time to time.

This helps to avoid what we used to call "SAD STORIES" !!

[Howard LewisParticipant @howardlewis46836]

What you call "waves" are the form of each thread.

In the case of Whitworth form threads, (BSW, BSF, BSP and BSB – British Standard Brass ) the angle of the thread is 55 degrees.

The Depth of the thread is related to the pitch, by a formula, which need not concern you as a user.

Thus, a 1/4 BSW is 20 tpi, with a depth of 0.0320", whereas a 3/8 BSF is 20 tpi and the depth is still 0.0320".

If it were a 1/4 BSF thread, it would be 26 tpi with a depth of 0.0246". So for a given size, the finer thread would have a shallower depth.

The 40 tpi Model Engineer series are Whit form, but have a thread depth of only 0.016"

If you do not have one, invest in a set of Zeus Charts. You will find them invaluable. I still use the ones that I bought as an Apprentice, back in 1958!

This lists the details of many sorts of threads, giving tpi, pitch, depth and core diameter, and in a separate table the correct tapping drill and clearance drill to be used.

Additionally, it includes allowances for when bending sheet metal, and Trigonometry tables, which you may also find useful

Find a Model Engineering Club near you, and join. You will then be likely to obtain actual hands on experience, with other more knowledgeable folk.

Howard

Fat Fingers strike again!

Edited By Howard Lewis on 28/08/2019 18:29:29

[David Standing 1Participant @davidstanding1]

I can only suggest, once again, you buy the five 'Workshop Practice' books I listed in your 'materials' thread.

Harold Hall's Metalworker's Data Book, no. 42 in the series, contains a huge amount of info on threads, and more.

The books are as cheap as chips on eBay, and worth their weight in gold.

I have two copies of no. 42, a dirty working copy in the workshop, and a clean reference copy in the man cave indoors.

[Chris TickTockParticipant @christicktock]

Posted by Howard Lewis on 28/08/2019 18:15:58:

What you call "waves" are the form of each thread.

In the case of Whitworth form threads, (BSW, BSF, BSP and BSB – British Standard Brass ) the angle of the thread is 55 degrees.

The Depth of the thread is related to the pitch, by a formula, which need not concern you as a user.

Thus, a 1/4 BSW is 20 tpi, with a depth of 0.0320", whereas a 3/8 BSF is 20 tpi and the depth is still 0.0320".

If it were a 1/4 BSF thread, it would be 26 tpi with a depth of 0.0246". So for a given size, the finer thread would have a shallower depth.

The 40 tpi Model Engineer series are Whit form, but have a thread depth of only 0.016"

If you do not have one, invest in a set of Zeus Charts. You will find them invaluable. I still use the ones that I bought as an Apprentice, back in 1958!

This lists the details of many sorts of threads, giving tpi, pitch, depth and core diameter, and in a separate table the correct tapping drill and clearance drill to be used.

Additionally, it includes allowances for when bending sheet metal, and Trigonometry tables, which you may also find useful

Find a Model Engineering Club near you, and join. You will then be likely to obtain actual hands on experience, with other more knowledgeable folk.

Howard

Fat Fingers strike again!

Edited By Howard Lewis on 28/08/2019 18:29:29

Great post Howard I have the modern equivalent of the 1958 Cards found on the web. At this stage just being aware of the parameters of different threads should suffice as reference can then always be made.

Regards

Chris

[Clive FosterParticipant @clivefoster55965]

When it comes to identifying unknown threads the compilation of threads in ascending size originally done by Andy Pugh and refined by other folk is pretty much unbeatable.

Much easier than normal listings 'cos you don't have to identify the thread type first.  Normal way is far better if you plan to cut threads tho'.

The essential "wot thread is it" identifier here :- **LINK** in text format which may need bit of massaging for easy reading.

A bit of web searching should find links to a pretty Excel file version, which I use.  Google should find a direct download link.

A pdf version here :- https://fromtheframeup.com/uploads/TT_Thread_size_chart.pdf 

There is also an HTML version here http://pages.cs.wisc.edu/~bolo/workshop/thread.html.

Clive.

Edited By Clive Foster on 29/08/2019 11:03:36

[Chris TickTockParticipant @christicktock]

Posted by Clive Foster on 29/08/2019 10:53:36:

When it comes to identifying unknown threads the compilation of threads in ascending size originally done by Andy Pugh and refined by other folk is pretty much unbeatable.

Much easier than normal listings 'cos you don't have to identify the thread type first. Normal way is far better if you plan to cut threads tho'.

The essential "wot thread is it" identifier here :- **LINK** in text format which may need bit of massaging for easy reading.

A bit of web searching should find links to a pretty Excel file version, which I use. Google should find a direct download link.

A pdf version here :- **LINK**

There is also an HTML version here **LINK**.

Clive.

Edited By Clive Foster on 29/08/2019 11:03:36

Great post Clive thanks

Chris

[SillyOldDufferModerator @sillyoldduffer]

Putting threads into context:

• Whitworth is the first standard thread, introduced about 1840, with 55° flanks. As a coarse thread Whitworth is well suited to the needs of Victorian and Heavy Engineering.
• In the USA, 25 years after Whitworth, Seller's proposed an improved thread; similar to Whitworth but simplified for manufacture, and with a stronger 60° thread form.
• On the Continent, where the metric system had almost entirely displaced local weights and measures, engineers developed coarse metric threads,
• As Light and Precision engineering developed, it was found that Whitworth, Sellers and Coarse metric were all inappropriate for small diameter fasteners and for some materials, like Brass and Steel. Fine thread versions were added to all three systems, but even they didn't satisfy all needs, notably Bicycles, Electrical, Instrumentation, and Aircraft. This led to the introduction of other thread standards, notably BA in the UK. BA is a scientifically designed thread (for electrical and other light work) and is interesting because although metric, it was carefully converted to inch measure because the engineers of the day (including Whitworth), felt that British Workmen were too thick to take kindly to metric.
• Over the same period, large numbers of other special threads were developed such as tapered threads for sealing joints on pipework, and square, buttress and ACME threads for power transmission. Some lasted, others faded away.
• Taken as a whole, by 1930 the sheer number of incompatible threads were a major obstacle to trade. This came to a head during WW2 when joint US/British military operations were compromised because American Nuts, Bolts and Spanners were incompatible with their very similar British equivalents. Supply of spares was complicated and repairs delayed. Such a mess, that the USA and British switched to a common system, the main feature of which is a 60° thread. In consequence, Whitworth faded from mainstream use since 1940 and is now rarely found. (Except on heritage machinery.)
• Since then, metrication has taken a heavy toll of Inch Threads. Dumping Whitworth fixed a compatibility problem between two close allies, but it did nothing for sales to the rest of the world. Today, apart perhaps from the USA, metric threads are almost universal in new equipment.
• Much confusion is still evident; I've owned cars which mixed all the main thread systems on the same vehicle, spent a small fortune on spanners, and never had a full stock of spare bolts. There is a lot of older equipment worth repairing that's held together by obsolescent thread systems.

Navigating this mess can be a problem for hobbyists. Trying to follow an old British or new American Project Book can be deeply confusing. What made sense in 1949 may not in 2019, and stuff easily obtained in the USA may be hard to find in Europe. I'd recommend going metric if general purpose making or repairing new equipment is your bag. Makes more sense to go Imperial if renovating old equipment, building models to Imperial Plans, or grandad gives you a fully equipped Imperial workshop. There are hobbyists who need to work with both systems, and it's certainly possible to do metric work on an imperial lathe and vice versa. Less amusing if you have to buy full sets of Imperial and Metric drills, taps, dies, spanners etc. because it soon gets expensive.

As a budding clockmaker, before tooling up, it's worth looking at a number of designs to see what threads are recommended and trying to standardise. It's unlikely any clock plans will call for Whitworth! American designs might call for UNF, British for BA, and German metric. Actually it may not matter much because designs can be tweaked to use any thread system, but it's all time and trouble. I'd be interested to hear from proper Horologists which thread system(s) they use in practice?

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Posted by SillyOldDuffer on 30/08/2019 09:02:10:

[ … ]

As a budding clockmaker, before tooling up, it's worth looking at a number of designs to see what threads are recommended and trying to standardise. It's unlikely any clock plans will call for Whitworth! American designs might call for UNF, British for BA, and German metric. Actually it may not matter much because designs can be tweaked to use any thread system, but it's all time and trouble. I'd be interested to hear from proper Horologists which thread system(s) they use in practice?

.

Dave,

That would probably depend upon how you care to define 'proper Horologists'

… potentially even more contentious than defining 'Model Engineers' !!

Whitworth threads may well have been used on the great Turret Clocks, and Thury was the Swiss Standard for watches and small clocks … Between those extremes pretty-much anything goes [including 'special' threads]

Perhaps the defining factor is that Horologists strive to keep things in good proportion …

MichaelG.

[DiogenesParticipant @diogenes]

Surely the term "Proper" in either discipline clearly refers to those who abstain from the use of Stainless Steel Socket Head Cap Screws?

[Michael GilliganParticipant @michaelgilligan61133]

[JasonBModerator @jasonb]

So the black ones are OK then

I'm sure Whitworth Instrument thread has found it's way onto clocks etc in the past, so best not to generalise with the word "Whitworth"

Edited By JasonB on 30/08/2019 10:19:13

[Nick Clarke 3Participant @nickclarke3]

Posted by SillyOldDuffer on 30/08/2019 09:02:10:

• Taken as a whole, by 1930 the sheer number of incompatible threads were a major obstacle to trade. This came to a head during WW2 when joint US/British military operations were compromised because American Nuts, Bolts and Spanners were incompatible with their very similar British equivalents. Supply of spares was complicated and repairs delayed. Such a mess, that the USA and British switched to a common system, the main feature of which is a 60° thread. In consequence, Whitworth faded from mainstream use since 1940 and is now rarely found. (Except on heritage machinery.)

My Granddad had some American spanners in his shed that apparently came from his time in the RAF in WW2. He said that when Merlin engines came from this country you got an engine, but if it was a American built one it came with a full tool kit and spanners – presumably because of this incompatibility. (real or imagined I suppose)

Because each and every US engine came with the tool kit everyone in the hangar ended up with one when the F/Sgt wasn't looking!

[egaParticipant @ega]

SOD:

Thanks for the useful recap!

[Chris TickTockParticipant @christicktock]

Posted by SillyOldDuffer on 30/08/2019 09:02:10:

Putting threads into context:

• Whitworth is the first standard thread, introduced about 1840, with 55° flanks. As a coarse thread Whitworth is well suited to the needs of Victorian and Heavy Engineering.
• In the USA, 25 years after Whitworth, Seller's proposed an improved thread; similar to Whitworth but simplified for manufacture, and with a stronger 60° thread form.
• On the Continent, where the metric system had almost entirely displaced local weights and measures, engineers developed coarse metric threads,
• As Light and Precision engineering developed, it was found that Whitworth, Sellers and Coarse metric were all inappropriate for small diameter fasteners and for some materials, like Brass and Steel. Fine thread versions were added to all three systems, but even they didn't satisfy all needs, notably Bicycles, Electrical, Instrumentation, and Aircraft. This led to the introduction of other thread standards, notably BA in the UK. BA is a scientifically designed thread (for electrical and other light work) and is interesting because although metric, it was carefully converted to inch measure because the engineers of the day (including Whitworth), felt that British Workmen were too thick to take kindly to metric.
• Over the same period, large numbers of other special threads were developed such as tapered threads for sealing joints on pipework, and square, buttress and ACME threads for power transmission. Some lasted, others faded away.
• Taken as a whole, by 1930 the sheer number of incompatible threads were a major obstacle to trade. This came to a head during WW2 when joint US/British military operations were compromised because American Nuts, Bolts and Spanners were incompatible with their very similar British equivalents. Supply of spares was complicated and repairs delayed. Such a mess, that the USA and British switched to a common system, the main feature of which is a 60° thread. In consequence, Whitworth faded from mainstream use since 1940 and is now rarely found. (Except on heritage machinery.)
• Since then, metrication has taken a heavy toll of Inch Threads. Dumping Whitworth fixed a compatibility problem between two close allies, but it did nothing for sales to the rest of the world. Today, apart perhaps from the USA, metric threads are almost universal in new equipment.
• Much confusion is still evident; I've owned cars which mixed all the main thread systems on the same vehicle, spent a small fortune on spanners, and never had a full stock of spare bolts. There is a lot of older equipment worth repairing that's held together by obsolescent thread systems.

Navigating this mess can be a problem for hobbyists. Trying to follow an old British or new American Project Book can be deeply confusing. What made sense in 1949 may not in 2019, and stuff easily obtained in the USA may be hard to find in Europe. I'd recommend going metric if general purpose making or repairing new equipment is your bag. Makes more sense to go Imperial if renovating old equipment, building models to Imperial Plans, or grandad gives you a fully equipped Imperial workshop. There are hobbyists who need to work with both systems, and it's certainly possible to do metric work on an imperial lathe and vice versa. Less amusing if you have to buy full sets of Imperial and Metric drills, taps, dies, spanners etc. because it soon gets expensive.

As a budding clockmaker, before tooling up, it's worth looking at a number of designs to see what threads are recommended and trying to standardise. It's unlikely any clock plans will call for Whitworth! American designs might call for UNF, British for BA, and German metric. Actually it may not matter much because designs can be tweaked to use any thread system, but it's all time and trouble. I'd be interested to hear from proper Horologists which thread system(s) they use in practice?

Dave

Great post Dave somewhat spoilt by introducing provocative terms. Horology is such a broad subject that to be a master would take more than a lifetime. I for one with but a few years experience with clocks understand this. But then what makes a 'proper' horologist or 'proper' machinist come to that is difficult to define and why on a forum would we wish to.. much better not to use such language. Any antique clock repair man should know there are all manner of threads used and often clock makers used their own threads.

Chris

[SillyOldDufferModerator @sillyoldduffer]

Posted by Chris TickTock on 30/08/2019 11:21:56:

Posted by SillyOldDuffer on 30/08/2019 09:02:10:….

Dave

Great post Dave somewhat spoilt by introducing provocative terms. Horology is such a broad subject that to be a master would take more than a lifetime. I for one with but a few years experience with clocks understand this. But then what makes a 'proper' horologist or 'proper' machinist come to that is difficult to define and why on a forum would we wish to.. much better not to use such language. …

Chris

Whoops, I was trying not to be provocative! Was it describing British Workmen as too thick to understand metric, or calling the multitude of conflicting standards a mess, or 'Proper Horologist' that touched a nerve?

I stand by what I said: thread standards are a mess and here's the opinion of the 'First Report of the BA Small Screws Committee (1882) : 'The question of the introduction of the metrical system occupied the serious consideration of the committee, but, considering the fact that it is not generally adopted in engineering or manufacture in England, and that it is as yet little understood by our workmen, it was thought better to suggest no change in this direction.'

By 'Proper Horologist' I simply meant anyone who knows more about clocks than me! Although interested in the theory and history of clocks I've never made one myself, apart from Meccano and electronic. So my views on clock threads in the real world are inferior to those of anyone who has actually built a clock. In general I'm massively ignorant on ways and means compared with any forum member doing serious clock making. That's why I asked the question, and I think Michael gave a good answer.

Dave

 

Edited By SillyOldDuffer on 30/08/2019 15:23:33

[Howard LewisParticipant @howardlewis46836]

Standardising threads , as Whitworth and Maudslay did, greatly simplified life. Others came after and made improvements that suited their particular needs. Until then, it was the whim of the local blacksmith, as to what he made.

We use a "standard" thread because it it is simpler for us to interface with others. If you want to make your product unique, (so that you have sole control of the aftermarket, you build in a unique feature, such as the need for a 7mm Allen Key to service the brakes, or a unique thread.. You could go for a 12mm x 8 tpi. with an angle of 45 degrees,for instance).

But for the rest of us, standardisation makes life much easier! Hence our need for thread gauges, to help identify the thread standard with which we are dealing.

But "oddballs" will crop up. Such as the 1.125 inch x 12 tpi used by Myford, which over the years, has effectively become a standard. Ditto for Boxford, or Raglan with their threads. My lathe mandrel is 2.25 inch x 8 tpi Whit form, which may be described a standard, IF you happen to have one of its clones or derivatives.

The thread for a drain plunger, at least in UK, is 3/4 x 7 tpi Whit form. Try cutting one 1/2 inch long! Europe still uses BSP in the guise of Gas.

Enough of my ramblings

Howard

[Chris TickTockParticipant @christicktock]

Posted by Howard Lewis on 31/08/2019 12:33:31:

Standardising threads , as Whitworth and Maudslay did, greatly simplified life. Others came after and made improvements that suited their particular needs. Until then, it was the whim of the local blacksmith, as to what he made.

We use a "standard" thread because it it is simpler for us to interface with others. If you want to make your product unique, (so that you have sole control of the aftermarket, you build in a unique feature, such as the need for a 7mm Allen Key to service the brakes, or a unique thread.. You could go for a 12mm x 8 tpi. with an angle of 45 degrees,for instance).

But for the rest of us, standardisation makes life much easier! Hence our need for thread gauges, to help identify the thread standard with which we are dealing.

Howard you are a gem and plainly a font of knowledge.

Regards

Chris

But "oddballs" will crop up. Such as the 1.125 inch x 12 tpi used by Myford, which over the years, has effectively become a standard. Ditto for Boxford, or Raglan with their threads. My lathe mandrel is 2.25 inch x 8 tpi Whit form, which may be described a standard, IF you happen to have one of its clones or derivatives.

The thread for a drain plunger, at least in UK, is 3/4 x 7 tpi Whit form. Try cutting one 1/2 inch long! Europe still uses BSP in the guise of Gas.

Enough of my ramblings

Howard

[Author]

Posts