Nige,

My experience, such as it is, of British made hobby machines of that era suggests small whitworth thread sizes, especially if tapped into cast-iron.

Nige

On the 7 series lathes the equivalent adjusters are 2 BA, so I should start there.

Michael Gilligan:

"British equipment used BSW or BSF, as appropriate, for sizes down to 1/4" and BA for sizes below that"

Interesting cutoff point; 2 BA is pretty close to 3/16 BSF (and to M5). I wonder how much the odd BA sizes were used – in electrical equipment, perhaps.

It's a shame that British Standards are not in the public domain.

ega. I personally have never come across odd BA threads being used in industry ( Now someone will prove me wrong )

Roy

Roy – Fountain Pens.

7BA was used by Parker as the thread for the little decorative jewel that screwed into the end of the Parker 51 cap. In the US they used a similar size but they are not exactly interchangeable. The Parker Pens plant in Newhaven produced several million of these, and all the jewels/tassies (as they are sometimes called) were turned from bar stock to get the correct pearlescence in the material with a 7BA threaded spigot.

I've made one from brass, & it's something I have no plans to repeat. It's a right PITA.

Regards,

Richard

Edited By richardandtracy on 12/06/2017 16:00:57

Look forward to it, even though both ball pens and Montblanc's are outside my area of expertise. MB pens are ones where I'm unable to afford to become interested!

Regards,

Richard.

I've come across quite a few 3BA threads on electrical terminals. Trust them to be awkward!

The Whitworth thread was arrived at by standardising industry 'best practice' of the day. Whitworth visited a large number of manufactories, all of whom were doing their own thing, and based his thread form and sizes on average practice. This was done before steel became common, and in consequence the thread is best suited to the softer materials of the mid 19th Century, in particular the various forms of Iron and Brass.

By the end of the 19th Century, steel was by far the most common engineering metal, and technology had moved into precision work. The shortcomings of the original Whitworth standard were well understood, and several alternatives had emerged in the UK and abroad. The one adopted in the UK was BSF. This filled the gap so far as light and heavy engineering were concerned but, being derived from BSW, it was not ideal for instrumentation or electrical work. For that reason the UK adopted BA. Unlike BSW and BSF this is a scientifically designed thread, well suited to small work.

So, BSW and BSF were deprecated partly to improve standardisation, and partly because – in small sizes – there are better alternatives.

The Meccano thread is an interesting special case. Meccano an engineering toy. Little fingers make and dismantle bolted connections repeatedly. For that purpose the coarse BSW thread is ideal; it's difficult to cross-thread, quick to tighten and undo, and need not be well made. In comparison, BA and Metric threads are much better fasteners, but they're harder to use.

BSW and BSF survived for so long only because they were so common. If you own a railway with millions of BSW nuts and bolts holding the track together, you won't be keen to change it even if much better is available. On an old railway there's not much sense in going metric. On a new one you'd be daft not to.

Dave

If I'd got a little further into MEW256 before hitting the keyboard, I'd have seen the article 'Lehman Archer and BA Taps'.

Based on material provided by Eric Clark, it's a good read on the origins of the BA thread.

The article was written by mild mannered Neil Wyatt whom we now know to be Super Adept Man. Good job Neil isn't a fan of the Balding Lathe, because that would make him 'Balding Beaver Man'. That doesn't have the same cachet at all. No photoshopping please!

Dave

.

Oops … I hadn't read that either.

MichaelG.

Following Michael Gs full title of the BA, I wonder if any body could name any other of their activites???????????

Some local (E Devon) reading revealed that on a whim they decided to measure the difference in tidal range between the mouth of the R Axe and Westquantoxhead on the N Somerset coast No particular reason just seemed an interesting thing to do……….

John