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Metric screw thread measurements?
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Lieutenant Scott
Oct 22, 2012, 2:26:45 PM10/22/12
to
I had a screw that I wished to replace with a longer one, so I measured the diameter and ended up with a replacement too thin.
My rough measurement of the original screw was 3.5mm, so I ordered an M3.5. I've since measured the original with a calliper and got 3.75mm. The replacement M3.5 screw is 3.25mm on the calliper. What gives?
Anyone wishing to check my calliper - the screws in a lightswitch are identical in diameter to the incorrect replacement M3.5, which my calliper says is 3.25mm.
This says I'm measuring correctly:
http://en.wikipedia.org/wiki/ISO_metric_screw_thread
This suggests screws are 0.1mm thinner than they should be:
http://www.metricscrews.us/index.php?main_page=page&id=3
--
http://petersparrots.com
http://petersphotos.com
"His idea of safe sex is an `X' spray-painted on the rump of animals that are known to kick."
My rough measurement of the original screw was 3.5mm, so I ordered an M3.5. I've since measured the original with a calliper and got 3.75mm. The replacement M3.5 screw is 3.25mm on the calliper. What gives?
Anyone wishing to check my calliper - the screws in a lightswitch are identical in diameter to the incorrect replacement M3.5, which my calliper says is 3.25mm.
This says I'm measuring correctly:
http://en.wikipedia.org/wiki/ISO_metric_screw_thread
This suggests screws are 0.1mm thinner than they should be:
http://www.metricscrews.us/index.php?main_page=page&id=3
--
http://petersparrots.com
http://petersphotos.com
"His idea of safe sex is an `X' spray-painted on the rump of animals that are known to kick."
harry
Oct 23, 2012, 2:44:47 AM10/23/12
to
On Oct 22, 7:26 pm, "Lieutenant Scott" <n...@spam.com> wrote:
> I had a screw that I wished to replace with a longer one, so I measured the diameter and ended up with a replacement too thin.
>
> My rough measurement of the original screw was 3.5mm, so I ordered an M3.5. I've since measured the original with a calliper and got 3.75mm. The replacement M3.5 screw is 3.25mm on the calliper. What gives?
>
> Anyone wishing to check my calliper - the screws in a lightswitch are identical in diameter to the incorrect replacement M3.5, which my calliper says is 3.25mm.
>
> This says I'm measuring correctly:http://en.wikipedia.org/wiki/ISO_metric_screw_thread
>
> This suggests screws are 0.1mm thinner than they should be:http://www.metricscrews.us/index.php?main_page=page&id=3
>
> --http://petersparrots.comhttp://petersphotos.com
> I had a screw that I wished to replace with a longer one, so I measured the diameter and ended up with a replacement too thin.
>
> My rough measurement of the original screw was 3.5mm, so I ordered an M3.5. I've since measured the original with a calliper and got 3.75mm. The replacement M3.5 screw is 3.25mm on the calliper. What gives?
>
> Anyone wishing to check my calliper - the screws in a lightswitch are identical in diameter to the incorrect replacement M3.5, which my calliper says is 3.25mm.
>
> This says I'm measuring correctly:http://en.wikipedia.org/wiki/ISO_metric_screw_thread
>
> This suggests screws are 0.1mm thinner than they should be:http://www.metricscrews.us/index.php?main_page=page&id=3
>
>
> "His idea of safe sex is an `X' spray-painted on the rump of animals that are known to kick."
It's probably not metric. Try BA.
> "His idea of safe sex is an `X' spray-painted on the rump of animals that are known to kick."
Lieutenant Scott
Oct 23, 2012, 3:38:34 AM10/23/12
to
On Tue, 23 Oct 2012 07:44:47 +0100, harry <harry...@btinternet.com> wrote:
> On Oct 22, 7:26 pm, "Lieutenant Scott" <n...@spam.com> wrote:
>> I had a screw that I wished to replace with a longer one, so I measured the diameter and ended up with a replacement too thin.
>>
>> My rough measurement of the original screw was 3.5mm, so I ordered an M3.5. I've since measured the original with a calliper and got 3.75mm. The replacement M3.5 screw is 3.25mm on the calliper. What gives?
>>
>> Anyone wishing to check my calliper - the screws in a lightswitch are identical in diameter to the incorrect replacement M3.5, which my calliper says is 3.25mm.
>>
>> This says I'm measuring correctly: http://en.wikipedia.org/wiki/ISO_metric_screw_thread
>>
>> This suggests screws are 0.1mm thinner than they should be: http://www.metricscrews.us/index.php?main_page=page&id=3
>
> On Oct 22, 7:26 pm, "Lieutenant Scott" <n...@spam.com> wrote:
>> I had a screw that I wished to replace with a longer one, so I measured the diameter and ended up with a replacement too thin.
>>
>> My rough measurement of the original screw was 3.5mm, so I ordered an M3.5. I've since measured the original with a calliper and got 3.75mm. The replacement M3.5 screw is 3.25mm on the calliper. What gives?
>>
>> Anyone wishing to check my calliper - the screws in a lightswitch are identical in diameter to the incorrect replacement M3.5, which my calliper says is 3.25mm.
>>
>> This says I'm measuring correctly: http://en.wikipedia.org/wiki/ISO_metric_screw_thread
>>
>> This suggests screws are 0.1mm thinner than they should be: http://www.metricscrews.us/index.php?main_page=page&id=3
>
> It's probably not metric. Try BA.
It's M4. I got some from a neighbour.
So I now have M3.5 and M4 screws (they were labelled as such in the packets) that are both 0.25mm thinner than expected. And I checked with his callipers too.
The second link above suggests that they would be 0.1mm too thin. I don't see why they should be thinner at all.
"All you need is love, money, broadband, good health, satellite TV, a fast car, ......." - The Beatles
Dave Plowman (News)
Oct 23, 2012, 6:05:36 AM10/23/12
to
In article <op.wmmfika8ytk5n5@i7-940>,
the common ones are a full mm so you just go to the next full mm above
what the measurement is. 3.5mm, of course, being the odd one in common use
as it's for electrical sockets, etc.
You have to be careful with computer etc fixings. Some are actually
american, rather than metric sizes.
--
*I started out with nothing... and I still have most of it.
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
Lieutenant Scott <n...@spam.com> wrote:
> So I now have M3.5 and M4 screws (they were labelled as such in the
> packets) that are both 0.25mm thinner than expected. And I checked with
> his callipers too.
Basically, metric screw sizes refer to the clearance hole needed. Most of
> So I now have M3.5 and M4 screws (they were labelled as such in the
> packets) that are both 0.25mm thinner than expected. And I checked with
> his callipers too.
the common ones are a full mm so you just go to the next full mm above
what the measurement is. 3.5mm, of course, being the odd one in common use
as it's for electrical sockets, etc.
You have to be careful with computer etc fixings. Some are actually
american, rather than metric sizes.
--
*I started out with nothing... and I still have most of it.
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
michael adams
Oct 23, 2012, 6:36:02 AM10/23/12
to
"Lieutenant Scott" <n...@spam.com> wrote in message
news:op.wmmfika8ytk5n5@i7-940...
>
> So I now have M3.5 and M4 screws (they were labelled as such in the packets)
> that are both 0.25mm thinner than expected. And I checked with his callipers
> too.
>
> The second link above suggests that they would be 0.1mm too thin. I don't see
> why they should be thinner at all.
All nominal screw sizes come in both coarse and fine threads.
> So I now have M3.5 and M4 screws (they were labelled as such in the packets)
> that are both 0.25mm thinner than expected. And I checked with his callipers
> too.
>
> The second link above suggests that they would be 0.1mm too thin. I don't see
> why they should be thinner at all.
One big difference is that the height of the ridges are higher
in coarse threads - there's less taken off. The measured diameter
will be larger, Apparently the angle is slightly different as well.
Among other things. However AFAIAA all nominal sized screws - male threads
will fit the equivalent nominal size nuts - female threads. However
coarse and fine threads may be used for different applications based
on their properties. Apparently coarse threads thread faster while
fine threads are less subject to loosening as a result of vibration.
Yet all are interchangeable and will fit onto the equivalent size
nut or bolt whether fine or coarse. Which is the most imprtant test
regardless of what a digital caliper or any other measuring
tells you.
I think this is correct, but just to be sure you might like to ask
at the customer service desk next time you're in B&Q or Wickes.
michael adams
...
Baz
Oct 23, 2012, 6:42:10 AM10/23/12
to
"michael adams" <mjad...@ukonline.co.uk> wrote in message
news:FqGdnTH4R92E7hvN...@brightview.co.uk...
Baz
michael adams
Oct 23, 2012, 7:02:00 AM10/23/12
to
"Baz" <bras...@REMOVEmsn.com> wrote in message
news:lo2dnfmoUZoI6RvN...@bt.com...
correct".
> What a load of rubbish.
As Your answer will presumably be of intest to the OP as well.
As he'll finally get his question answered.
michael adams
...
>
> Baz
>
Dave Plowman (News)
Oct 23, 2012, 8:00:15 AM10/23/12
to
In article <FqGdnTH4R92E7hvN...@brightview.co.uk>,
Fine or coarse refers to mainly the number of threads per inch. (TPI) It
may be possible to force different types of thread (but the same diameter)
with the same or very close TPI to mate. But then why would you?
--
*I never drink anything stronger than gin before breakfast *
michael adams <mjad...@ukonline.co.uk> wrote:
> Apparently coarse threads thread faster while
> fine threads are less subject to loosening as a result of vibration.
> Yet all are interchangeable and will fit onto the equivalent size
> nut or bolt whether fine or coarse.
Would 'bollocks' be the best way to describe this?
> Apparently coarse threads thread faster while
> fine threads are less subject to loosening as a result of vibration.
> Yet all are interchangeable and will fit onto the equivalent size
> nut or bolt whether fine or coarse.
Fine or coarse refers to mainly the number of threads per inch. (TPI) It
may be possible to force different types of thread (but the same diameter)
with the same or very close TPI to mate. But then why would you?
--
*I never drink anything stronger than gin before breakfast *
Alan Braggins
Oct 23, 2012, 8:07:49 AM10/23/12
to
In article <FqGdnTH4R92E7hvN...@brightview.co.uk>, michael adams wrote:
>Yet all are interchangeable and will fit onto the equivalent size
>nut or bolt whether fine or coarse.
Please tell me you are joking.
>Yet all are interchangeable and will fit onto the equivalent size
>nut or bolt whether fine or coarse.
The Other Mike
Oct 23, 2012, 8:13:58 AM10/23/12
to
On Tue, 23 Oct 2012 11:36:02 +0100, "michael adams" <mjad...@ukonline.co.uk>
wrote:
>All nominal screw sizes come in both coarse and fine threads.
Partly correct for some thread series
>One big difference is that the height of the ridges are higher
>in coarse threads - there's less taken off.
No
>The measured diameter will be larger
No
>Apparently the angle is slightly different as well.
Total bollocks
--
wrote:
>All nominal screw sizes come in both coarse and fine threads.
>One big difference is that the height of the ridges are higher
>in coarse threads - there's less taken off.
>The measured diameter will be larger
>Apparently the angle is slightly different as well.
--
polygonum
Oct 23, 2012, 8:20:22 AM10/23/12
to
http://en.wikipedia.org/wiki/ISO_metric_screw_thread
--
Rod
The Natural Philosopher
Oct 23, 2012, 8:33:31 AM10/23/12
to
michael adams wrote:
> "Lieutenant Scott" <n...@spam.com> wrote in message
> news:op.wmmfika8ytk5n5@i7-940...
>> So I now have M3.5 and M4 screws (they were labelled as such in the packets)
>> that are both 0.25mm thinner than expected. And I checked with his callipers
>> too.
>>
>> The second link above suggests that they would be 0.1mm too thin. I don't see
>> why they should be thinner at all.
>
> All nominal screw sizes come in both coarse and fine threads.
> One big difference is that the height of the ridges are higher
> in coarse threads - there's less taken off. The measured diameter
> will be larger, Apparently the angle is slightly different as well.
> Among other things. However AFAIAA all nominal sized screws - male threads
> will fit the equivalent nominal size nuts - female threads. However
> coarse and fine threads may be used for different applications based
> on their properties. Apparently coarse threads thread faster while
> fine threads are less subject to loosening as a result of vibration.
> Yet all are interchangeable and will fit onto the equivalent size
> nut or bolt whether fine or coarse. Which is the most imprtant test
> regardless of what a digital caliper or any other measuring
> tells you.
>
> I think this is correct,
I think one phrase in it was broadly correct, but the rest was mostly
> "Lieutenant Scott" <n...@spam.com> wrote in message
> news:op.wmmfika8ytk5n5@i7-940...
>> So I now have M3.5 and M4 screws (they were labelled as such in the packets)
>> that are both 0.25mm thinner than expected. And I checked with his callipers
>> too.
>>
>> The second link above suggests that they would be 0.1mm too thin. I don't see
>> why they should be thinner at all.
>
> All nominal screw sizes come in both coarse and fine threads.
> One big difference is that the height of the ridges are higher
> in coarse threads - there's less taken off. The measured diameter
> will be larger, Apparently the angle is slightly different as well.
> Among other things. However AFAIAA all nominal sized screws - male threads
> will fit the equivalent nominal size nuts - female threads. However
> coarse and fine threads may be used for different applications based
> on their properties. Apparently coarse threads thread faster while
> fine threads are less subject to loosening as a result of vibration.
> Yet all are interchangeable and will fit onto the equivalent size
> nut or bolt whether fine or coarse. Which is the most imprtant test
> regardless of what a digital caliper or any other measuring
> tells you.
>
> I think this is correct,
bollocks
but just to be sure you might like to ask
> at the customer service desk next time you're in B&Q or Wickes.
>
>
> michael adams
>
> ...
>
>> --
>> http://petersparrots.com
>> http://petersphotos.com
>>
>> "All you need is love, money, broadband, good health, satellite TV, a fast
>> car, ......." - The Beatles
>
>
Ineptocracy
(in-ep-toc’-ra-cy) – a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.
The Natural Philosopher
Oct 23, 2012, 8:36:09 AM10/23/12
to
Dave Plowman (News) wrote:
> In article <FqGdnTH4R92E7hvN...@brightview.co.uk>,
> michael adams <mjad...@ukonline.co.uk> wrote:
>> Apparently coarse threads thread faster while
>> fine threads are less subject to loosening as a result of vibration.
>> Yet all are interchangeable and will fit onto the equivalent size
>> nut or bolt whether fine or coarse.
>
> Would 'bollocks' be the best way to describe this?
>
> Fine or coarse refers to mainly the number of threads per inch. (TPI) It
> may be possible to force different types of thread (but the same diameter)
> with the same or very close TPI to mate. But then why would you?
>
cost you only have a 4BA nut and an M3.5 threaded screw
> In article <FqGdnTH4R92E7hvN...@brightview.co.uk>,
> michael adams <mjad...@ukonline.co.uk> wrote:
>> Apparently coarse threads thread faster while
>> fine threads are less subject to loosening as a result of vibration.
>> Yet all are interchangeable and will fit onto the equivalent size
>> nut or bolt whether fine or coarse.
>
> Would 'bollocks' be the best way to describe this?
>
> Fine or coarse refers to mainly the number of threads per inch. (TPI) It
> may be possible to force different types of thread (but the same diameter)
> with the same or very close TPI to mate. But then why would you?
>
I had the strangest dreasm this morning. I dreamt that Barack Obama
gave me a 6mm screw.
Why on earth would I dream that?
polygonum
Oct 23, 2012, 8:37:55 AM10/23/12
to
On 23/10/2012 13:36, The Natural Philosopher wrote:
> Dave Plowman (News) wrote:
>> In article <FqGdnTH4R92E7hvN...@brightview.co.uk>,
>> michael adams <mjad...@ukonline.co.uk> wrote:
>>> Apparently coarse threads thread faster while
>>> fine threads are less subject to loosening as a result of vibration.
>>> Yet all are interchangeable and will fit onto the equivalent size
>>> nut or bolt whether fine or coarse.
>>
>> Would 'bollocks' be the best way to describe this?
>>
>> Fine or coarse refers to mainly the number of threads per inch. (TPI) It
>> may be possible to force different types of thread (but the same
>> diameter)
>> with the same or very close TPI to mate. But then why would you?
>>
> cost you only have a 4BA nut and an M3.5 threaded screw
>
> I had the strangest dreasm this morning. I dreamt that Barack Obama
> gave me a 6mm screw.
>
> Why on earth would I dream that?
>
>
Wasn't it Clinton who was better known for giving people...
> Dave Plowman (News) wrote:
>> In article <FqGdnTH4R92E7hvN...@brightview.co.uk>,
>> michael adams <mjad...@ukonline.co.uk> wrote:
>>> Apparently coarse threads thread faster while
>>> fine threads are less subject to loosening as a result of vibration.
>>> Yet all are interchangeable and will fit onto the equivalent size
>>> nut or bolt whether fine or coarse.
>>
>> Would 'bollocks' be the best way to describe this?
>>
>> Fine or coarse refers to mainly the number of threads per inch. (TPI) It
>> may be possible to force different types of thread (but the same
>> diameter)
>> with the same or very close TPI to mate. But then why would you?
>>
> cost you only have a 4BA nut and an M3.5 threaded screw
>
> I had the strangest dreasm this morning. I dreamt that Barack Obama
> gave me a 6mm screw.
>
> Why on earth would I dream that?
>
>
--
Rod
michael adams
Oct 23, 2012, 8:39:13 AM10/23/12
to
"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
news:52e3261...@davenoise.co.uk...
> In article <FqGdnTH4R92E7hvN...@brightview.co.uk>,
> michael adams <mjad...@ukonline.co.uk> wrote:
>> Apparently coarse threads thread faster while
>> fine threads are less subject to loosening as a result of vibration.
Which is correct according to numerous sources.
> michael adams <mjad...@ukonline.co.uk> wrote:
>> Apparently coarse threads thread faster while
>> fine threads are less subject to loosening as a result of vibration.
>> Yet all are interchangeable and will fit onto the equivalent size
>> nut or bolt whether fine or coarse.
>
> Would 'bollocks' be the best way to describe this?
>
> Fine or coarse refers to mainly the number of threads per inch. (TPI) It
> may be possible to force different types of thread (but the same diameter)
> with the same or very close TPI to mate. But then why would you?
scews of the same nominal size appear to differ.
Do you yourself have an explanation for this ?
As it would clearly be of use to the OP.
michael adams
...
michael adams
Oct 23, 2012, 8:39:23 AM10/23/12
to
"polygonum" <rmoud...@vrod.co.uk> wrote in message
news:aengc9...@mid.individual.net...
trying to discover why the diameters of various metric scews apppear
to differ by small amounts, perhaps you would be kind enough to explain why
this is.
michael adams
>
> --
> Rod
The Natural Philosopher
Oct 23, 2012, 8:42:22 AM10/23/12
to
headline would be'
And gave it back.
Too much Savile discussion is probably at the root of it, and The
Election. Perhaps my wife had the news on..
The Natural Philosopher
Oct 23, 2012, 8:46:19 AM10/23/12
to
At or around 3.5mm is M3.5, 4BA, and something like 5/32" UNF. I domnt
think Ive seen UNC or whitworth done that size, but there you go,
In addition there is BSP, and another standrad thread whose name escapes
me.
All in all there are probably 10-20 thread forms in use worldwide, or
which have been in use in the last 60 years. None of them fit each other.
>
> michael adams
>
>
>
>
>
>
>
>> --
>> Rod
Dave Plowman (News)
Oct 23, 2012, 9:01:40 AM10/23/12
to
In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
--
*A day without sunshine is like... night.*
michael adams <mjad...@ukonline.co.uk> wrote:
> The OP was trying to discover why the diameters of various metric
> scews of the same nominal size appear to differ.
> Do you yourself have an explanation for this ?
They're likely not both metric screws as I hinted at in my answer.
> The OP was trying to discover why the diameters of various metric
> scews of the same nominal size appear to differ.
> Do you yourself have an explanation for this ?
--
*A day without sunshine is like... night.*
Dave Plowman (News)
Oct 23, 2012, 9:03:09 AM10/23/12
to
In article <k663is$cue$1...@news.albasani.net>,
sizes being the obvious one.
--
*I will always cherish the initial misconceptions I had about you
The Natural Philosopher <t...@invalid.invalid> wrote:
> All in all there are probably 10-20 thread forms in use worldwide, or
> which have been in use in the last 60 years. None of them fit each other.
Some do, depending on your definition of 'fit'. Some UNC and some metric
> All in all there are probably 10-20 thread forms in use worldwide, or
> which have been in use in the last 60 years. None of them fit each other.
sizes being the obvious one.
--
*I will always cherish the initial misconceptions I had about you
michael adams
Oct 23, 2012, 9:10:58 AM10/23/12
to
news:52e32bb...@davenoise.co.uk...
there's a 0.2mm difference in the recommended tap drill sizes for
fine and coarse metric threads
http://www.engineeringtoolbox.com/metric-threads-d_777.html
michael adams
...
> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
> michael adams <mjad...@ukonline.co.uk> wrote:
>> The OP was trying to discover why the diameters of various metric
>> scews of the same nominal size appear to differ.
>
>> Do you yourself have an explanation for this ?
>
> They're likely not both metric screws as I hinted at in my answer.
The only reason I suggested fine and coarse threads is becaue
> michael adams <mjad...@ukonline.co.uk> wrote:
>> The OP was trying to discover why the diameters of various metric
>> scews of the same nominal size appear to differ.
>
>> Do you yourself have an explanation for this ?
>
> They're likely not both metric screws as I hinted at in my answer.
there's a 0.2mm difference in the recommended tap drill sizes for
fine and coarse metric threads
http://www.engineeringtoolbox.com/metric-threads-d_777.html
michael adams
...
polygonum
Oct 23, 2012, 9:14:25 AM10/23/12
to
>> I don't think he has worked out how to use Wiki yet:
>>
>> http://en.wikipedia.org/wiki/ISO_metric_screw_thread
>
>
> As you're clearly very knowledgeable on the subject, as the OP was
> trying to discover why the diameters of various metric scews apppear
> to differ by small amounts, perhaps you would be kind enough to
> explain why this is.
>
>
> michael adams
>
If I were so very knowledgeable about threads, I would have answered on
>>
>> http://en.wikipedia.org/wiki/ISO_metric_screw_thread
>
>
> As you're clearly very knowledgeable on the subject, as the OP was
> trying to discover why the diameters of various metric scews apppear
> to differ by small amounts, perhaps you would be kind enough to
> explain why this is.
>
>
> michael adams
>
that basis. But I am sufficiently with it to try to find an answer.
Further, I might well post bollocks on occasion, but most often I have
actually tried to look something up, if appropriate.
The Wiki link identifies quite a lot about threads.
--
Rod
Dave Baker
Oct 23, 2012, 9:20:23 AM10/23/12
to
news:XuudnfKOn_z3ChvN...@brightview.co.uk...
thread is smaller than than of a finer pitched bolt of the same o/d. The
tapping drill therefore needs to be smaller. The o/d of the thread is
however the same.
--
Dave Baker
>
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:52e32bb...@davenoise.co.uk...
>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>> michael adams <mjad...@ukonline.co.uk> wrote:
>>> The OP was trying to discover why the diameters of various metric
>>> scews of the same nominal size appear to differ.
>>
>>> Do you yourself have an explanation for this ?
>>
>> They're likely not both metric screws as I hinted at in my answer.
>
> The only reason I suggested fine and coarse threads is becaue
> there's a 0.2mm difference in the recommended tap drill sizes for
> fine and coarse metric threads
>
> http://www.engineeringtoolbox.com/metric-threads-d_777.html
Duh! Of course there is. The root diameter of an Xmm nominal o/d coarse
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:52e32bb...@davenoise.co.uk...
>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>> michael adams <mjad...@ukonline.co.uk> wrote:
>>> The OP was trying to discover why the diameters of various metric
>>> scews of the same nominal size appear to differ.
>>
>>> Do you yourself have an explanation for this ?
>>
>> They're likely not both metric screws as I hinted at in my answer.
>
> The only reason I suggested fine and coarse threads is becaue
> there's a 0.2mm difference in the recommended tap drill sizes for
> fine and coarse metric threads
>
> http://www.engineeringtoolbox.com/metric-threads-d_777.html
thread is smaller than than of a finer pitched bolt of the same o/d. The
tapping drill therefore needs to be smaller. The o/d of the thread is
however the same.
--
Dave Baker
John Williamson
Oct 23, 2012, 9:30:09 AM10/23/12
to
michael adams wrote:
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:52e32bb...@davenoise.co.uk...
>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>> michael adams <mjad...@ukonline.co.uk> wrote:
>>> The OP was trying to discover why the diameters of various metric
>>> scews of the same nominal size appear to differ.
>>> Do you yourself have an explanation for this ?
>> They're likely not both metric screws as I hinted at in my answer.
>
> The only reason I suggested fine and coarse threads is becaue
> there's a 0.2mm difference in the recommended tap drill sizes for
> fine and coarse metric threads
>
> http://www.engineeringtoolbox.com/metric-threads-d_777.html
>
That's because the tapping drill has to match the core diameter of the
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:52e32bb...@davenoise.co.uk...
>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>> michael adams <mjad...@ukonline.co.uk> wrote:
>>> The OP was trying to discover why the diameters of various metric
>>> scews of the same nominal size appear to differ.
>>> Do you yourself have an explanation for this ?
>> They're likely not both metric screws as I hinted at in my answer.
>
> The only reason I suggested fine and coarse threads is becaue
> there's a 0.2mm difference in the recommended tap drill sizes for
> fine and coarse metric threads
>
> http://www.engineeringtoolbox.com/metric-threads-d_777.html
>
thread, and coarse threads have a smaller core diameter than fine
threads of the same external size.
Maybe doing "O" level metalwork wasn't such a waste as has been suggested.
By the way, if you want to interchange nuts between thread standards,
then the closest is Whitworth and UNC, as they use the same thread pitch
for their respective diameters. It's not ideal, though, as the threads
are different shapes (Whitworth was normally rolled with rounded tips
and bottoms, while UNC was lathe cut with sharp tips and bottoms. The
angles are also different.), so the strength of the unit is much
reduced. BSF and UNF can't be interchanged and will strip the threads if
forced, and BA is in a world of its own...
--
Tciao for Now!
John.
The Natural Philosopher
Oct 23, 2012, 9:31:11 AM10/23/12
to
Dave Plowman (News) wrote:
> In article <k663is$cue$1...@news.albasani.net>,
> The Natural Philosopher <t...@invalid.invalid> wrote:
>> All in all there are probably 10-20 thread forms in use worldwide, or
>> which have been in use in the last 60 years. None of them fit each other.
>
> Some do, depending on your definition of 'fit'. Some UNC and some metric
> sizes being the obvious one.
>
Fit as in not the way wide legged trousers 'fit' chavs.
> In article <k663is$cue$1...@news.albasani.net>,
> The Natural Philosopher <t...@invalid.invalid> wrote:
>> All in all there are probably 10-20 thread forms in use worldwide, or
>> which have been in use in the last 60 years. None of them fit each other.
>
> Some do, depending on your definition of 'fit'. Some UNC and some metric
> sizes being the obvious one.
>
The Other Mike
Oct 23, 2012, 9:33:09 AM10/23/12
to
On Tue, 23 Oct 2012 14:03:09 +0100, "Dave Plowman (News)" <da...@davenoise.co.uk>
wrote:
>In article <k663is$cue$1...@news.albasani.net>,
> The Natural Philosopher <t...@invalid.invalid> wrote:
>> All in all there are probably 10-20 thread forms in use worldwide, or
>> which have been in use in the last 60 years. None of them fit each other.
>
>Some do, depending on your definition of 'fit'. Some UNC and some metric
>sizes being the obvious one.
0BA and M6 x 1 being a case in point
--
wrote:
>In article <k663is$cue$1...@news.albasani.net>,
> The Natural Philosopher <t...@invalid.invalid> wrote:
>> All in all there are probably 10-20 thread forms in use worldwide, or
>> which have been in use in the last 60 years. None of them fit each other.
>
>Some do, depending on your definition of 'fit'. Some UNC and some metric
>sizes being the obvious one.
--
The Other Mike
Oct 23, 2012, 9:33:17 AM10/23/12
to
On Tue, 23 Oct 2012 14:10:58 +0100, "michael adams" <mjad...@ukonline.co.uk>
wrote:
>
a metric coarse or fine pitch screw thread is always the same regardless of the
nominal diameter.
With regards to ISO metric threads every dimension is derived from the nominal
diameter and the pitch. The angle is always the same, 60 degrees.
--
wrote:
>
>"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
>news:52e32bb...@davenoise.co.uk...
>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>> michael adams <mjad...@ukonline.co.uk> wrote:
>>> The OP was trying to discover why the diameters of various metric
>>> scews of the same nominal size appear to differ.
>>
>>> Do you yourself have an explanation for this ?
>>
>> They're likely not both metric screws as I hinted at in my answer.
>
>The only reason I suggested fine and coarse threads is becaue
>there's a 0.2mm difference in the recommended tap drill sizes for
>fine and coarse metric threads
>
>http://www.engineeringtoolbox.com/metric-threads-d_777.html
The 0.2mm is purely related to the pitch of the thread. The overall diameter of
>news:52e32bb...@davenoise.co.uk...
>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>> michael adams <mjad...@ukonline.co.uk> wrote:
>>> The OP was trying to discover why the diameters of various metric
>>> scews of the same nominal size appear to differ.
>>
>>> Do you yourself have an explanation for this ?
>>
>> They're likely not both metric screws as I hinted at in my answer.
>
>The only reason I suggested fine and coarse threads is becaue
>there's a 0.2mm difference in the recommended tap drill sizes for
>fine and coarse metric threads
>
>http://www.engineeringtoolbox.com/metric-threads-d_777.html
a metric coarse or fine pitch screw thread is always the same regardless of the
nominal diameter.
With regards to ISO metric threads every dimension is derived from the nominal
diameter and the pitch. The angle is always the same, 60 degrees.
--
The Natural Philosopher
Oct 23, 2012, 9:34:28 AM10/23/12
to
John Williamson wrote:
> michael adams wrote:
>> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
>> news:52e32bb...@davenoise.co.uk...
>>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>>> michael adams <mjad...@ukonline.co.uk> wrote:
>>>> The OP was trying to discover why the diameters of various metric
>>>> scews of the same nominal size appear to differ.
>>>> Do you yourself have an explanation for this ?
>>> They're likely not both metric screws as I hinted at in my answer.
>>
>> The only reason I suggested fine and coarse threads is becaue
>> there's a 0.2mm difference in the recommended tap drill sizes for
>> fine and coarse metric threads
>>
>> http://www.engineeringtoolbox.com/metric-threads-d_777.html
>>
> That's because the tapping drill has to match the core diameter of the
> thread, and coarse threads have a smaller core diameter than fine
> threads of the same external size.
>
> Maybe doing "O" level metalwork wasn't such a waste as has been suggested.
>
> By the way, if you want to interchange nuts between thread standards,
> then the closest is Whitworth and UNC, as they use the same thread pitch
> for their respective diameters. It's not ideal, though, as the threads
> are different shapes (Whitworth was normally rolled with rounded tips
> and bottoms, while UNC was lathe cut with sharp tips and bottoms.
I thought it was the other way around?
> michael adams wrote:
>> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
>> news:52e32bb...@davenoise.co.uk...
>>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>>> michael adams <mjad...@ukonline.co.uk> wrote:
>>>> The OP was trying to discover why the diameters of various metric
>>>> scews of the same nominal size appear to differ.
>>>> Do you yourself have an explanation for this ?
>>> They're likely not both metric screws as I hinted at in my answer.
>>
>> The only reason I suggested fine and coarse threads is becaue
>> there's a 0.2mm difference in the recommended tap drill sizes for
>> fine and coarse metric threads
>>
>> http://www.engineeringtoolbox.com/metric-threads-d_777.html
>>
> That's because the tapping drill has to match the core diameter of the
> thread, and coarse threads have a smaller core diameter than fine
> threads of the same external size.
>
> Maybe doing "O" level metalwork wasn't such a waste as has been suggested.
>
> By the way, if you want to interchange nuts between thread standards,
> then the closest is Whitworth and UNC, as they use the same thread pitch
> for their respective diameters. It's not ideal, though, as the threads
> are different shapes (Whitworth was normally rolled with rounded tips
> and bottoms, while UNC was lathe cut with sharp tips and bottoms.
The
> angles are also different.), so the strength of the unit is much
> reduced. BSF and UNF can't be interchanged and will strip the threads if
> forced, and BA is in a world of its own...
>
--
michael adams
Oct 23, 2012, 10:00:35 AM10/23/12
to
"The Other Mike" <rootpa...@somewhereorother.com> wrote in message
news:m47d88hhu440jsg4u...@4ax.com...
I'd never previously bothered with any of this, but maybe like
the OP I bought a couple of digital calipers from Aldi.
Using vernier calipers, although good enough for identifying
drill bits, there's always a possibility of user error or
misreading such as you wouldn't want to swear blind as to
any particular reading. Without using a magnifying glass
anyway .But now for just �8.50 everybody is an expert.
The outside diameter of the thread of the 6mm (Toolstation)
bolts I just measured is 5.86 mm. And yes I pressed zero
first.
michael adams
...
>
>
> --
John Williamson
Oct 23, 2012, 10:03:51 AM10/23/12
to
The Natural Philosopher wrote:
http://www.boltscience.com/pages/screw4.htm
For Whitworth and BSF,
http://www.boltscience.com/pages/screw7.htm
For Unified and ISO threads.
I may have mis-remembered the manufacturing methods, as I finished the
course over 40 years ago...
I suspect that either thread could be produced within tolerances by
either method, but the rounded shape would be easier to roll than cut,
the squared off shape easier to cut than roll and when made manually,
the tap and die are both equally convenient to use.
> John Williamson wrote:
>> By the way, if you want to interchange nuts between thread standards,
>> then the closest is Whitworth and UNC, as they use the same thread
>> pitch for their respective diameters. It's not ideal, though, as the
>> threads are different shapes (Whitworth was normally rolled with
>> rounded tips and bottoms, while UNC was lathe cut with sharp tips and
>> bottoms.
>
> I thought it was the other way around?
>
For shape:-
>> By the way, if you want to interchange nuts between thread standards,
>> then the closest is Whitworth and UNC, as they use the same thread
>> pitch for their respective diameters. It's not ideal, though, as the
>> threads are different shapes (Whitworth was normally rolled with
>> rounded tips and bottoms, while UNC was lathe cut with sharp tips and
>> bottoms.
>
> I thought it was the other way around?
>
http://www.boltscience.com/pages/screw4.htm
For Whitworth and BSF,
http://www.boltscience.com/pages/screw7.htm
For Unified and ISO threads.
I may have mis-remembered the manufacturing methods, as I finished the
course over 40 years ago...
I suspect that either thread could be produced within tolerances by
either method, but the rounded shape would be easier to roll than cut,
the squared off shape easier to cut than roll and when made manually,
the tap and die are both equally convenient to use.
Dave Plowman (News)
Oct 23, 2012, 10:05:02 AM10/23/12
to
In article <XuudnfKOn_z3ChvN...@brightview.co.uk>,
smaller sizes.
--
*Cleaned by Stevie Wonder, checked by David Blunkett*
michael adams <mjad...@ukonline.co.uk> wrote:
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:52e32bb...@davenoise.co.uk...
> > In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
> > michael adams <mjad...@ukonline.co.uk> wrote:
> >> The OP was trying to discover why the diameters of various metric
> >> scews of the same nominal size appear to differ.
> >
> >> Do you yourself have an explanation for this ?
> >
> > They're likely not both metric screws as I hinted at in my answer.
> The only reason I suggested fine and coarse threads is becaue
> there's a 0.2mm difference in the recommended tap drill sizes for
> fine and coarse metric threads
It would be very unlikely to come across fine and coarse threads in the
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:52e32bb...@davenoise.co.uk...
> > In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
> > michael adams <mjad...@ukonline.co.uk> wrote:
> >> The OP was trying to discover why the diameters of various metric
> >> scews of the same nominal size appear to differ.
> >
> >> Do you yourself have an explanation for this ?
> >
> > They're likely not both metric screws as I hinted at in my answer.
> The only reason I suggested fine and coarse threads is becaue
> there's a 0.2mm difference in the recommended tap drill sizes for
> fine and coarse metric threads
smaller sizes.
--
*Cleaned by Stevie Wonder, checked by David Blunkett*
John Williamson
Oct 23, 2012, 10:19:22 AM10/23/12
to
diameter of the unthreaded portion, which is a close fit in the hole.
The threaded portion is specified to be smaller to allow for easier
assembly and to allow for manufacturing tolerances. If you were to
continue the shape of the thread to a sharp edge, then it would be the
same diameter as the shank.
Read this page:-
http://www.boltscience.com/pages/screw2.htm
and the following ones for a reasonably complete explanation of the
history and theory of bolts.
In fact, the whole site is a mine of information about threaded fasteners.
tony sayer
Oct 23, 2012, 10:14:44 AM10/23/12
to
In article <k663be$an0$5...@news.albasani.net>, The Natural Philosopher
<t...@invalid.invalid> scribeth thus
--
Tony Sayer
<t...@invalid.invalid> scribeth thus
>polygonum wrote:
>> On 23/10/2012 13:36, The Natural Philosopher wrote:
>>> Dave Plowman (News) wrote:
>>>> In article <FqGdnTH4R92E7hvN...@brightview.co.uk>,
>>>> michael adams <mjad...@ukonline.co.uk> wrote:
>>>>> Apparently coarse threads thread faster while
>>>>> fine threads are less subject to loosening as a result of vibration.
>>>>> Yet all are interchangeable and will fit onto the equivalent size
>>>>> nut or bolt whether fine or coarse.
>>>>
>>>> Would 'bollocks' be the best way to describe this?
>>>>
>>>> Fine or coarse refers to mainly the number of threads per inch. (TPI) It
>>>> may be possible to force different types of thread (but the same
>>>> diameter)
>>>> with the same or very close TPI to mate. But then why would you?
>>>>
>>> cost you only have a 4BA nut and an M3.5 threaded screw
>>>
>>> I had the strangest dreasm this morning. I dreamt that Barack Obama
>>> gave me a 6mm screw.
>>>
>>> Why on earth would I dream that?
>>>
>>>
>> Wasn't it Clinton who was better known for giving people...
>>
>That was how the dream ended. I said 'you know Mr president, what te
>headline would be'
>
http://www.romneytaxplan.com/
>> On 23/10/2012 13:36, The Natural Philosopher wrote:
>>> Dave Plowman (News) wrote:
>>>> In article <FqGdnTH4R92E7hvN...@brightview.co.uk>,
>>>> michael adams <mjad...@ukonline.co.uk> wrote:
>>>>> Apparently coarse threads thread faster while
>>>>> fine threads are less subject to loosening as a result of vibration.
>>>>> Yet all are interchangeable and will fit onto the equivalent size
>>>>> nut or bolt whether fine or coarse.
>>>>
>>>> Would 'bollocks' be the best way to describe this?
>>>>
>>>> Fine or coarse refers to mainly the number of threads per inch. (TPI) It
>>>> may be possible to force different types of thread (but the same
>>>> diameter)
>>>> with the same or very close TPI to mate. But then why would you?
>>>>
>>> cost you only have a 4BA nut and an M3.5 threaded screw
>>>
>>> I had the strangest dreasm this morning. I dreamt that Barack Obama
>>> gave me a 6mm screw.
>>>
>>> Why on earth would I dream that?
>>>
>>>
>> Wasn't it Clinton who was better known for giving people...
>>
>That was how the dream ended. I said 'you know Mr president, what te
>headline would be'
>
--
Tony Sayer
John Williamson
Oct 23, 2012, 10:23:50 AM10/23/12
to
Dave Plowman (News) wrote:
> In article <XuudnfKOn_z3ChvN...@brightview.co.uk>,
> michael adams <mjad...@ukonline.co.uk> wrote:
>
>> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
>> news:52e32bb...@davenoise.co.uk...
>>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>>> michael adams <mjad...@ukonline.co.uk> wrote:
>>>> The OP was trying to discover why the diameters of various metric
>>>> scews of the same nominal size appear to differ.
>>>> Do you yourself have an explanation for this ?
>>> They're likely not both metric screws as I hinted at in my answer.
>
>> The only reason I suggested fine and coarse threads is becaue
>> there's a 0.2mm difference in the recommended tap drill sizes for
>> fine and coarse metric threads
>
> It would be very unlikely to come across fine and coarse threads in the
> smaller sizes.
>
Looks at two computer screws, both metric, both about 3.5mm, one coarse
> In article <XuudnfKOn_z3ChvN...@brightview.co.uk>,
> michael adams <mjad...@ukonline.co.uk> wrote:
>
>> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
>> news:52e32bb...@davenoise.co.uk...
>>> In article <luCdna6Ce_xkEhvN...@brightview.co.uk>,
>>> michael adams <mjad...@ukonline.co.uk> wrote:
>>>> The OP was trying to discover why the diameters of various metric
>>>> scews of the same nominal size appear to differ.
>>>> Do you yourself have an explanation for this ?
>>> They're likely not both metric screws as I hinted at in my answer.
>
>> The only reason I suggested fine and coarse threads is becaue
>> there's a 0.2mm difference in the recommended tap drill sizes for
>> fine and coarse metric threads
>
> It would be very unlikely to come across fine and coarse threads in the
> smaller sizes.
>
theaded, one fine. CBA to get out the micrometer to check if they're
both metric, but as they both came out of the same case....
The Natural Philosopher
Oct 23, 2012, 10:40:26 AM10/23/12
to
thread used principally to hold disk drives in place.
Dave Plowman (News)
Oct 23, 2012, 10:40:04 AM10/23/12
to
In article <aennk5...@mid.individual.net>,
fixings.
--
*Forget the Joneses, I keep us up with the Simpsons.
John Williamson <johnwil...@btinternet.com> wrote:
> It would be very unlikely to come across fine and coarse threads in the
> > smaller sizes.
> >
> Looks at two computer screws, both metric, both about 3.5mm, one coarse
> theaded, one fine. CBA to get out the micrometer to check if they're
> both metric, but as they both came out of the same case....
The coarse one is very likely an american thread. Most often found for HD
> It would be very unlikely to come across fine and coarse threads in the
> > smaller sizes.
> >
> Looks at two computer screws, both metric, both about 3.5mm, one coarse
> theaded, one fine. CBA to get out the micrometer to check if they're
> both metric, but as they both came out of the same case....
fixings.
--
*Forget the Joneses, I keep us up with the Simpsons.
dochol...@gmail.com
Oct 23, 2012, 11:54:49 AM10/23/12
to
On Tuesday, October 23, 2012 3:43:42 PM UTC+1, Dave Plowman (News) wrote:
> In article <aennk5...@mid.individual.net>,
> In article <aennk5...@mid.individual.net>,
> John Williamson wrote:
> > Looks at two computer screws, both metric, both about 3.5mm, one coarse
> > theaded, one fine. CBA to get out the micrometer to check if they're
> > both metric, but as they both came out of the same case....
>
>
>
> The coarse one is very likely an american thread. Most often found for HD
> fixings.
+1
> > Looks at two computer screws, both metric, both about 3.5mm, one coarse
> > theaded, one fine. CBA to get out the micrometer to check if they're
> > both metric, but as they both came out of the same case....
>
>
>
> The coarse one is very likely an american thread. Most often found for HD
> fixings.
Hard disk fixing screws are normally UNC, CD/DVD drive fixings are normally metric, so you'd expect to find both in any computer...
michael adams
Oct 23, 2012, 12:00:30 PM10/23/12
to
"John Williamson" <johnwil...@btinternet.com> wrote in message
news:aennbq...@mid.individual.net...
never have thought to measure the diameter of any screw.
Metric or otherwise. Similarly I doubt that the OP would have
been quite so confident in his measurements in order to ask
his question.
I now seem to remember having come unstuck discussing the
finer points of screw dimensions on here before.
> The diameter of a bolt is the
> diameter of the unthreaded portion, which is a close fit in the
> hole. The threaded portion is specified to be smaller to allow for
> easier assembly and to allow for manufacturing tolerances. If you
> were to continue the shape of the thread to a sharp edge, then it
> would be the same diameter as the shank.
>
> Read this page:-
>
> http://www.boltscience.com/pages/screw2.htm
>
> and the following ones for a reasonably complete explanation of the
> history and theory of bolts.
role as an essential element in the evolution of precision tools -
Ramsden
Maudslay and some French engineer and their original screw cutting
lathes - which could then be used to produce lead screws for lathes
which could then be used to duplicate the originals
With the real precison laying in arranging the screw threads
perpendicular to one another. i.e one compete revolution
in one threaded rod only rotating another threaded rod by
a 1/60 th of a turn. Which in turn etc. etc.
Without checking ISTR the screw is a form of inclined plane.
>
> In fact, the whole site is a mine of information about threaded
> fasteners.
...
Lieutenant Scott
Oct 23, 2012, 12:59:25 PM10/23/12
to
On Tue, 23 Oct 2012 11:05:36 +0100, Dave Plowman (News) <da...@davenoise.co.uk> wrote:
> In article <op.wmmfika8ytk5n5@i7-940>,
> Lieutenant Scott <n...@spam.com> wrote:
>> So I now have M3.5 and M4 screws (they were labelled as such in the
>> packets) that are both 0.25mm thinner than expected. And I checked with
>> his callipers too.
>
> Basically, metric screw sizes refer to the clearance hole needed.
That wasn't what Wikipedia said, but it would make sense.
> Most of
> the common ones are a full mm so you just go to the next full mm above
> what the measurement is. 3.5mm, of course, being the odd one in common use
> as it's for electrical sockets, etc.
>
> You have to be careful with computer etc fixings. Some are actually
> american, rather than metric sizes.
>
--
http://petersparrots.com
http://petersphotos.com
Thought for the Day:
The Bible teaches us to love your neighbour, and the Kama Sutra explains how.
> In article <op.wmmfika8ytk5n5@i7-940>,
> Lieutenant Scott <n...@spam.com> wrote:
>> So I now have M3.5 and M4 screws (they were labelled as such in the
>> packets) that are both 0.25mm thinner than expected. And I checked with
>> his callipers too.
>
> Basically, metric screw sizes refer to the clearance hole needed.
That wasn't what Wikipedia said, but it would make sense.
> Most of
> the common ones are a full mm so you just go to the next full mm above
> what the measurement is. 3.5mm, of course, being the odd one in common use
> as it's for electrical sockets, etc.
>
> You have to be careful with computer etc fixings. Some are actually
> american, rather than metric sizes.
>
--
http://petersparrots.com
http://petersphotos.com
Thought for the Day:
The Bible teaches us to love your neighbour, and the Kama Sutra explains how.
Lieutenant Scott
Oct 23, 2012, 12:59:46 PM10/23/12
to
On Tue, 23 Oct 2012 13:33:31 +0100, The Natural Philosopher <t...@invalid.invalid> wrote:
> michael adams wrote:
>> "Lieutenant Scott" <n...@spam.com> wrote in message
>> news:op.wmmfika8ytk5n5@i7-940...
>>> why they should be thinner at all.
>> will be larger, Apparently the angle is slightly different as well.
>> Among other things. However AFAIAA all nominal sized screws - male threads
>> will fit the equivalent nominal size nuts - female threads. However
>> coarse and fine threads may be used for different applications based
>> on their properties. Apparently coarse threads thread faster while
>> regardless of what a digital caliper or any other measuring
>> tells you.
>>
>> I think this is correct,
>
> I think one phrase in it was broadly correct, but the rest was mostly
> bollocks
Then what is your answer?
> michael adams wrote:
>> "Lieutenant Scott" <n...@spam.com> wrote in message
>> news:op.wmmfika8ytk5n5@i7-940...
>>> So I now have M3.5 and M4 screws (they were labelled as such in the packets)
>>> that are both 0.25mm thinner than expected. And I checked with his callipers
>>> too.
>>>
>>> The second link above suggests that they would be 0.1mm too thin. I don't see
>>> that are both 0.25mm thinner than expected. And I checked with his callipers
>>> too.
>>>
>>> why they should be thinner at all.
>>
>> All nominal screw sizes come in both coarse and fine threads.
>> All nominal screw sizes come in both coarse and fine threads.
>> One big difference is that the height of the ridges are higher
>> in coarse threads - there's less taken off. The measured diameter
>> will be larger, Apparently the angle is slightly different as well.
>> Among other things. However AFAIAA all nominal sized screws - male threads
>> will fit the equivalent nominal size nuts - female threads. However
>> coarse and fine threads may be used for different applications based
>> on their properties. Apparently coarse threads thread faster while
>> fine threads are less subject to loosening as a result of vibration.
>> Yet all are interchangeable and will fit onto the equivalent size
>> nut or bolt whether fine or coarse. Which is the most imprtant test
>> Yet all are interchangeable and will fit onto the equivalent size
>> regardless of what a digital caliper or any other measuring
>> tells you.
>>
>> I think this is correct,
>
> I think one phrase in it was broadly correct, but the rest was mostly
> bollocks
Then what is your answer?
Nightjar
Oct 25, 2012, 9:13:25 AM10/25/12
to
On 23/10/2012 13:39, michael adams wrote:
...
> As you're clearly very knowledgeable on the subject, as the OP was
> trying to discover why the diameters of various metric scews apppear
> to differ by small amounts, perhaps you would be kind enough to explain why
> this is.
The OP is fairly expert at posting apparently reasonable requests that
> trying to discover why the diameters of various metric scews apppear
> to differ by small amounts, perhaps you would be kind enough to explain why
> this is.
end up spiralling into long and involved threads, if you are tempted
into answering them. I have a book that devotes 18 pages exclusively to
measuring threads. It is not as simple a subject as it might appear.
Colin Bignell
Dave Plowman (News)
Oct 25, 2012, 10:49:48 AM10/25/12
to
In article <cfidneViwZdnpxTN...@giganews.com>,
screws is the local shed you can make some reasonable assumptions.
--
Is the hardness of the butter proportional to the softness of the bread?*
Nightjar <c...@insert.my.surname.here.me.uk> wrote:
> The OP is fairly expert at posting apparently reasonable requests that
> end up spiralling into long and involved threads, if you are tempted
> into answering them. I have a book that devotes 18 pages exclusively to
> measuring threads. It is not as simple a subject as it might appear.
Quite - but you have to read between the lines. When the source of such
> The OP is fairly expert at posting apparently reasonable requests that
> end up spiralling into long and involved threads, if you are tempted
> into answering them. I have a book that devotes 18 pages exclusively to
> measuring threads. It is not as simple a subject as it might appear.
screws is the local shed you can make some reasonable assumptions.
--
Is the hardness of the butter proportional to the softness of the bread?*
Grimly Curmudgeon
Oct 27, 2012, 3:33:12 PM10/27/12
to
On Tue, 23 Oct 2012 14:33:09 +0100, The Other Mike
<rootpa...@somewhereorother.com> wrote:
>>Some do, depending on your definition of 'fit'. Some UNC and some metric
>>sizes being the obvious one.
>
>0BA and M6 x 1 being a case in point
Camera threads of nominal (historic) 1/4" Whitworth are commonly
<rootpa...@somewhereorother.com> wrote:
>>Some do, depending on your definition of 'fit'. Some UNC and some metric
>>sizes being the obvious one.
>
>0BA and M6 x 1 being a case in point
bodged with UNC bolts. Since they usually only need three or four
turns, it's got away with.
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