Myford ML4 Threads

Can anybody help me with the thread size on the gib strip adjusters on the Myford ML4 please? Those on the compound slide and cross slide appear to be a smaller diameter than those for the half nut gib strip on the apron. I don't yet have thread pitch gauges for the 'imperial' threads so removing one to check doesn't yield me any useful data at the moment ! Imperial pitch gauges next on a growing shopping list !! Many thanks.

Nige

Nige:

You could compare the screw to a likely-looking tap if you have one.

At a guess, the gib screws are BA and an ordinary imperial thread pitch gauge won't cover the BA pitches.

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.

Thank you ega and Clive. I do have BA taps and dies so I could make a comparison as ega suggests. Not sure what small Whitworth taps and dies aI have but will check. I have ordered a set of Whitworth thread pitch gauges so that will help check Clive's suggestion. Thanks again

Nige

Nige

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

.

... and with very few exceptions [Meccano comes to mind] it's fair to say that British equipment used BSW or BSF, as appropriate, for sizes down to 1/4" and BA for sizes below that. ... I'm pretty sure that recommendation is enshrined in a British Standard.

MichaelG.

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 :

In the hope that this very brief extract will cause no offence to the British Standards Institute, I quote from the Foreword [page iii] of BS 450:1958

MichaelG.

________

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

Roy

Michael: Thank you for the info on the ML7, it makes sense that there would be some 'standardisation' of fasteners across the range of products.

ega: The BSI Standards reference is interesting. I know from my own experience, from just before we went metric with a vengeance, that we did indeed use Whitworth and BSF down to 1/4 inch and BA threads for anything smaller. However, we used to manufacture a LOT of iron work, Main Distribution Frame (MDF) extensions mostly, which had a seemingly huge number of BA threaded holes ! It seemed that sometimes the monotony of tapping holes was only relieved by the other monotonous task that came into the workshop, that of cutting and then arc welding hundreds of feet of mild steel to make overhead cable runway: ahh, the joys of a BT regional workshop

Nige

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

richard and tracy:

I well remember the sleek Parker 51; my mother had one (her handwriting was beautiful to look at and hard to read).

In view of your obvious expertise in this area I plan to send you a query via PM about Montblanc ball pens.

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.

Michael Gilligan:

Thank you for the interesting BSI extract. I was confident that given a little encouragement you would come up with chapter and verse!

Am I right in thinking that the underlying aim was to codify and reduce the number of standard threads? I'm not clear as to why the small BSW and BSF sizes were "strongly deprecated"; presumably there was some reason for the continuing interest in them? You mention the Meccano screw which was, I think, 5/32" BSW; this seems to have been the case when I bought a set for a teenager some ten or more years ago but by then it had a 3mm hex recess head and 1/4" square nut.

The BA thread form seems significantly different from the Whitworth standard and I guess might have been more expensive to manufacture.

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

!

Edited By duncan webster on 12/06/2017 18:12:27

Edited By duncan webster on 12/06/2017 18:13:15

Edited By duncan webster on 12/06/2017 18:14:02

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

.

Dave [Silly Old Duffer] has already covered much of this in his 18:41:50 post ... so I will just add that the BA threads were properly 'thought out' ... hence the enthusiasm for their adoption.

Full title of the B.A. being 'the British Association for the Advancement of Science'.

MichaelG.

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

Spoilsport! .

I can't guarantee Nick G won't just ignore you though - (I hope he does ).