Anybody out there go a conversion sheet for BA to Metric.

Thanks

Mike

BA is metric, sort of.
What's your problem?

Jordan

Mike Francis wrote:
Anybody out there go a conversion sheet for BA to Metric.

Thanks

Mike

Jordan wrote:

BA is metric, sort of.

Oh no, not again. BA is not metric.
The "B" in BA stands for "British", so this _can't_ be metric. :-)

Nick
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BA thread are metric based, 0BA is 6mm diameter x 1mm pitch with 47.5
degree included angle IIRC. The BA number is used as a power in a
formula to produce the thread details.

Nick Müller wrote:

Jordan wrote:

BA is metric, sort of.


Oh no, not again. BA is not metric.
The "B" in BA stands for "British", so this _can't_ be metric. :-)

Nick

We Brits are quite capable of working in metric thank you ;-)

BA series was created in 1890's to help standardise a thead form for the
emerging electrical industry.

The base is BA 0 which is a 6mm dia by 1mm pitch thread

Each additional pitch is 0.9 x pitch of previous size rounded to nearest
..01mm so they go 1.0, 0.9, 0.81, 0.73, ...

Diameter D is given by D = 6 x (P to the power 1.2) where P is the pitch

Core diameter is D - 1.2 x P

(Source Model Engineers Handbook - Tubal Cain ISBN 085242 715 8)

http://mdmetric.com/tech/thddat8.htm amongst many others has appropriate
charts

http://easyweb.easynet.co.uk/~chrish/threadch.htm has screwcutting details
for lathe with 8tpi leadscrew

Don Valentine

""Nick Müller"" wrote in message
...
Jordan wrote:

BA is metric, sort of.

Oh no, not again. BA is not metric.
The "B" in BA stands for "British", so this _can't_ be metric. :-)

Nick
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Don Valentine wrote:

We Brits are quite capable of working in metric thank you ;-)

Don't get me wrong, I think the Brits are among the best model
engineers.
But I had the discussion here about 3 years ago: BA is not metric. Look
at the standards of metric threads and you know why.


BA series was created in 1890's

At that time there was _nothing_ like metric threads and this also
explains why BA isn't metric.


Nick

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On Fri, 10 Jun 2005 13:23:42 +0200, (Nick Müller)
wrote:

Don Valentine wrote:

We Brits are quite capable of working in metric thank you ;-)

Don't get me wrong, I think the Brits are among the best model
engineers.
But I had the discussion here about 3 years ago: BA is not metric. Look
at the standards of metric threads and you know why.


BA series was created in 1890's

At that time there was _nothing_ like metric threads and this also
explains why BA isn't metric.

Nick, are you talking metric threads measured in metric units or are
you talking SI, not necessarily the same.
Mike in BC

It was designed in metric but spec'd in english units. It is not
ISO.........but then again metric pipe is british.

it is correct to say it is metric, since the thread pitches are metric



Nick Müller wrote:
Don Valentine wrote:


We Brits are quite capable of working in metric thank you ;-)


Don't get me wrong, I think the Brits are among the best model
engineers.
But I had the discussion here about 3 years ago: BA is not metric. Look
at the standards of metric threads and you know why.



BA series was created in 1890's


At that time there was _nothing_ like metric threads and this also
explains why BA isn't metric.


Nick

wrote:

Nick, are you talking metric threads measured in metric units or are

I guess I got you wrong. But this makes sense (not almost). If a thread
is measured in metric units, it's metric. :-)))

No, it's a even easier. If it is like M6 (M10*1,25, ...) it's metric.
The leading "M" gives the hint.
And I think we can agree that "M" != "BA"

Nick
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yourname wrote:

it is correct to say it is metric, since the thread pitches are metric

They arent metric. Look in the standard and you will only find pitches
of 0.2; 0.25; 0.35; 0.5; 0.75; 1; 1.25; 1.5; 2; ...

But BA has pitches of 1.0, 0.9, 0.81, 0.73
Next difference are the 47.5 degrees in contrast to the 60 degrees for
metric threads.

Sorry, but you should look into the standards before spreading such
missinformation.

Nick
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Nick Müller wrote:
yourname wrote:


it is correct to say it is metric, since the thread pitches are metric


They arent metric. Look in the standard and you will only find pitches
of 0.2; 0.25; 0.35; 0.5; 0.75; 1; 1.25; 1.5; 2; ...

But BA has pitches of 1.0, 0.9, 0.81, 0.73
Next difference are the 47.5 degrees in contrast to the 60 degrees for
metric threads.

Sorry, but you should look into the standards before spreading such
missinformation.

Nick

Perhaps YOU should look at the standards. BA #0, pitch .03937, major
diameter .2362 hmmm what the **** do you think that is?

It was apparently based on the Thury thread, a swiss system, which was,
you guessed it, metric. all the dimensions are in inch units because
thats what the British machinists could measure. It is not an ISO thread
and never was, but it is most certainly 'metric'

Your position is the same as saying that a 1/4-29 thread is not an
'inch' thread. It is not UNC or UNF, but it is most certainly 'inch'


ref:

http://www.britishfasteners.com/threads/

yourname wrote:

Perhaps YOU should look at the standards. BA #0, pitch .03937, major
diameter .2362 hmmm what the **** do you think that is?

Done. And how about BA1 BA2 ...?
And how about the 60deg. angle?
DIN ISO 13 defines what a metric thread is. And if it isn't following
DIN ISO 13, it isn't metric but Thury or whatever.
Do me (and yourself) the favour and look closely at the standard.


Your position is the same as saying that a 1/4-29 thread is not an
'inch' thread. It is not UNC or UNF, but it is most certainly 'inch'

By "inch" you mean it's Whitworth or Reynolds? This only shows me that
you know _dammned_ little about this subject.

Following your weird argumentation, any thread is metric if it is
measured in metric units.


I bail out ...

Nick

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Nick Müller wrote:
yourname wrote:


Perhaps YOU should look at the standards. BA #0, pitch .03937, major
diameter .2362 hmmm what the **** do you think that is?


Done. And how about BA1 BA2 ...?
And how about the 60deg. angle?
DIN ISO 13 defines what a metric thread is. And if it isn't following
DIN ISO 13, it isn't metric but Thury or whatever.
Do me (and yourself) the favour and look closely at the standard.





How many times do you have to be told that everyone knows it is not ISO
metric? Can you actually read?
Your position is the same as saying that a 1/4-29 thread is not an
'inch' thread. It is not UNC or UNF, but it is most certainly 'inch'


By "inch" you mean it's Whitworth or Reynolds? This only shows me that
you know _dammned_ little about this subject.

Following your weird argumentation, any thread is metric if it is
measured in metric units.


No it is metric if it was designed in metric, as was BA


I bail out ...

Apparently you bailed out years ago



Nick

BA (British Association) IS metric. When the original BA metric standards
are converted to dimensions in inches, the results are still correct, but
they are no longer in simplified units. That is why they seem so goofy. My
question: why are BA dimensions now expressed in inch units? Cheers, Dave
Anderson

"Mike Francis" wrote in message
...
Anybody out there go a conversion sheet for BA to Metric.

Thanks

Mike

David Anderson wrote:
BA (British Association) IS metric. When the original BA metric standards
are converted to dimensions in inches, the results are still correct, but
they are no longer in simplified units. That is why they seem so goofy. My
question: why are BA dimensions now expressed in inch units? Cheers, Dave
Anderson

"Mike Francis" wrote in message
...

Anybody out there go a conversion sheet for BA to Metric.

Thanks

Mike




Short answer: friggin Brits

"yourname" wrote in message news:x4Cqe.67$EH1.24@trndny03...
David Anderson wrote:
BA (British Association) IS metric. When the original BA metric
standards
are converted to dimensions in inches, the results are still correct,
but
they are no longer in simplified units. That is why they seem so goofy.
My
question: why are BA dimensions now expressed in inch units? Cheers,
Dave
Anderson

"Mike Francis" wrote in message
...

Anybody out there go a conversion sheet for BA to Metric.

Thanks

Mike




Short answer: friggin Brits
Friggin Yanks! Still using a measurement system based on the with of a
long dead foreign king's thumb when all the rest of the world is metric