BA to metric conversion

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.

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

Nick

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:

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

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 f*ck 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:

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.

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

How many times do you have to be told that everyone knows it is not ISO metric? Can you actually read?

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

Apparently you bailed out years ago

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

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