I’ve bought a 7R [ Myford, not AJS ]

[Jon GibbsParticipant @jongibbs59756]

As Michael says everything else on Myfords was BSF until metrication was eventually forced on them by metric coarse cap screws becoming much cheaper than BSF large head cap screws (Chapter 17 of Ian Bradley's book).

Since there's so little to choose between 2BA and 3/16 BSF, Neil's probably right that 2BA was just cheaper at the time.

Jon

[Michael GilliganParticipant @michaelgilligan61133]

Posted by CotswoldsPhil on 10/09/2014 13:02:39:

Myford seemed to like 2BA

.

Thanks for checking, Phil

Yes, 2BA was popular throughout British manufacturing.

Despite Neil's witty comment, I think move to M5 actually came when they had the opportunity to use Nylon-patch self locking grub screws. If correct, that should mean that [on the cross-slide gib adjusters] the hex-socket grub screws should be M5 self locking and all the slotted screws should be 2BA with lock nuts.

My real concern is that the current manufacturer's spares list does not seem to reflect that logic.

MichaelG.

.

P.S. … on mine, the two M5 screws that serve to lock [rather than adjust] the cross-slide do not have the Nylon patch [which is reasonable enough, I think]

[Neil WyattModerator @neilwyatt]

> Nylon-patch self locking grub screws

Now that's something I need, but struggling to find a supplier – can you get them as small as M3?

Neil

[Swarf, Mostly!Participant @swarfmostly]

Hi there,

When I started work in the defence electronics industry, 1954-ish, the practice as I remember it was initially BSF above 1/4" and B.A. below.

Beeston Myfords seem to have followed substantially the same practice.

Once NATO became an influence, the larger threads changed to UNF which was a sort of mollified ANF (to mollify the European NATO nations). And, where the design required a coarser thread, UNC (mollified ANC).

It all got a bit messy when the UK metricated.

Best regards,

Swarf, Mostly!

[Mike PooleParticipant @mikepoole82104]

Hi Michael,

My 7R has the same threads on the cross slide as you describe. The threads on the back of the bed for attaching accessories are 6mm, i could not get a 1/4 BSF screw to start and ran a 1/4BSF tap through, it took a bit more out than I was expecting, the pitch of 6mm and 1/4BSF are very close so I think no harm done and did the same for all the holes on the pad. They would have best been left as 6mm as BSF are not so readily available as metric. The Allen bolts holding the headstock to the bed are also metric. The Allen screws holding the apron to the carriage are also metric (M6). I expect Myford changed some of the bought in fastners to metric as supply became more difficult and expensive. After nearly 50 years of metrication BSF seems close to dead and only specialist suppliers to the classic vehicle market supply at a price.

Mike

Edited By Michael Poole on 10/09/2014 16:39:04

Edited By Michael Poole on 10/09/2014 16:49:07

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Poole on 10/09/2014 16:35:19:

… The threads on the back of the bed for attaching accessories are 6mm

… The Allen bolts holding the headstock to the bed are also metric.

… The Allen screws holding the apron to the carriage are also metric (M6).

.

Mike,

Thanks for those warnings … I shall proceed with great caution and set of good Allen Keys !!

MichaelG.

[Brian WoodParticipant @brianwood45127]

Hello again Michael,

I have rechecked the gib screws on the X slide of my ML7R and can confirm that ALL of them are M5 x 0.8. I only measured the head end in my posting earlier today, this time I took one right out..

Those securing the gib itself have small nylon pads abouit 5 threads back from the reduced section up to the rounded point.

The ML7R handbook describes these screws as Wedglok, the locking screws are longer by 4 mm at 20 mm and finish in blunt aquare ends at thread core diameter—–NO nylon pads on those two.

The handbook for the Super 7 describes the gib screws as Wedglok dog point quoting the size as M5 x 0.8 x 16mm and the locking screws as M5 x 0.8 x 20mm

These are NOT 2 BA, I proved that to my satisfaction earlier. I agree with you, the Myford stock listing is incorrect.

Regards

Brian

Edited By Brian Wood on 10/09/2014 19:24:34

[Michael GilliganParticipant @michaelgilligan61133]

Brian,

Thanks again … very thorough, and it exactly matches my findings.

MichaelG.

.

I wonder if Myford would like to follow Ketan's excellent example, and join the forum ?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 10/09/2014 14:56:07:

> Nylon-patch self locking grub screws

Now that's something I need, but struggling to find a supplier – can you get them as small as M3?

Neil

.

Neil,

For info. Details of Wedglok, here

I suspect that "inserted pellets" may be difficult to execute at M3 size, but I'm sure I have seen M3 with the bonded-on nylon patches [we just need to find you a supplier].

MichaelG.

Edited By Michael Gilligan on 10/09/2014 21:39:17

[Chris TriceParticipant @christrice43267]

I think the use of BA screws was more considered. The thread form of BA (47 1/2 degrees) was better suited to cast iron at that scale of screw but with the passage of time and metric overwhelming the more archaic threads, change was inevitable sooner or later.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Chris Trice on 11/09/2014 02:27:21:
I think the use of BA screws was more considered. The thread form of BA (47 1/2 degrees) was better suited to cast iron at that scale of screw …

.

Sorry, Chris, I don't follow your logic

I would [intuitively] have thought that 60 degree threads would be optimum for cast iron.

… I'm happy to be educated, if you can explain.

MichaelG.

[Chris TriceParticipant @christrice43267]

Gib screws are acting like little lockable feedscrews. That’s why most feedscrews don’t have metric threads but square or acme. BA offers a larger cross section thread more like an acme while still having a fine pitch to give finesse of adjustment. Unlike bolts which are just designed to be pulled up really tight and left, gibs are intended to be reset periodically.

[Chris TriceParticipant @christrice43267]

Unlike steel, cast iron isn’t fond of fine overly delicate threads. It tends to break up and strip easily.

[Ian S CParticipant @iansc]

Mike, those 6 mm threads that you retapped 1/4 BSF, are you sure they weren't 0 BA? Ian S C

[Mike PooleParticipant @mikepoole82104]

Hi Ian,

i can't tell now but 0ba is not a popular thread in my experience, I think BA was popular below 1/4" but I think a1/4" thread would be used rather than 0BA in cast iron Myford seem to like BSF even in cast iron whereas Whitworth was commonly used in cast iron as a coarse thread was recommended to avoid the possibility of the peaks of finer threads breaking up.

Mike

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Chris Trice on 11/09/2014 10:42:08:
Gib screws are acting like little lockable feedscrews. < etc. >

.

Chris,

It's a good story, but I don't buy it.

It seems much more likely that Myford was simply following British Standard recommendations.

I took the opportunity, this afternoon, to have a look at BS93: 2008

This includes, at Note 6, the clear statement:

" It is recommended that BA threads be used in preference to B.S.W. and B.S.F. threads for all threads smaller than 1/4 in diameter."

MichaelG.

.

P.S.  Here is some more info. with the usual caveat regarding anything published on a web page.

Edited By Michael Gilligan on 11/09/2014 21:05:33

Edited By Michael Gilligan on 11/09/2014 21:11:43

[Neil WyattModerator @neilwyatt]

Thanks for those links Michael. It's hard to believe such a small nylon insert can be that effective.

neil

[Michael GilliganParticipant @michaelgilligan61133]

Here is another one for you, Neil

… With test data. including M3

MichaelG.

.

Edit: and here is their M3 set-screw [grub screw] with Tuflok patch

… I didn't dare check the price, but at least we've confirmed they exist.

 

Edited By Michael Gilligan on 11/09/2014 22:34:01

Edited By Michael Gilligan on 11/09/2014 22:36:34

[Michael GilliganParticipant @michaelgilligan61133]

Too late to edit it again …

Here is the page to check Bossard prices.

MichaelG.

[Chris TriceParticipant @christrice43267]

” It is recommended that BA threads be used in preference to B.S.W. and B.S.F. threads for all threads smaller than 1/4 in diameter.”

Well, there must be a reason then for that recommendation to be made. However it is true that different materials suit different threads. Anyone observing engine studs that go into an aluminium block will note the different threads at each end and many American cast iron engines did, until recently, use quite coarse threads in their assembly. I don’t profess to remember or know the figures involved but clearly someone has set recommendations based on some criteria for a reason.

[Michael GilliganParticipant @michaelgilligan61133]

Chris [and anyone else interested]

I can't find a copy of Thury's original paper, but I have found this excellent book.

Chapter IV gives a good interpretation of Thury's work on the Swiss watch threads

Chapter V covers its adoption by the BA [British Association for the Advancement of Science]

Enjoy!

MichaelG.

.

Note: Due to insufficient resolution in the scans [thanks, Microsoft] some of the small digits in the formulae are illegible … but the descriptive explanations are good.

Edited By Michael Gilligan on 12/09/2014 07:30:00

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 12/09/2014 07:04:04:

Chris [and anyone else interested]

I can't find a copy of Thury's original paper, but I have found this excellent book.

< etc. >

.

Although no-one has expressed any interest …

I was sufficiently impressed with the Britannia Colchester book that I've bought a proper one [printed 1891].

So, that's another little Myford spare I can't afford.

MichaelG.

[MetalhackerParticipant @metalhacker]

A good threadlocking technique I found with model aircraft engine mounts, which is to put a short length of thin nylon fishing line down the hole before screwing in the bolt or grub screw. Voila a nyloc type thread

[Neil WyattModerator @neilwyatt]

Thanks for the suggestions. I will try the fishing line idea.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

For your continuing amusement …

When I removed the collar and gear from the rear of the headstock spindle; I was surprised to find a rather loose-fitting Woodruff Key.

Closer examination revealed that the key was "hand crafted" from material about 0.077" thick [but about 0.087" at the high spots, where the edges are burred] … The Key should be 0.125" thick,

Presumably the original key had been mislaid.

….

Now: Have a look at this photo, which is the view into the rear bearing assembly

… There is something a little unusual-looking, just below 3 o'clock …

A little closer:

Edited By Michael Gilligan on 17/09/2014 21:36:20

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