I've bought a 7R [ Myford, not AJS ]

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

neil

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

Too late to edit it again ...

Here is the page to check Bossard prices.

MichaelG.

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

.

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.

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

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

Neil

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

... In the immortal words of Rolf Harris:

"Can you see what it is yet ?"

MichaelG.

Looks a bit like a woodruff key to me. The pull on the preset loading collar is going to a bit lob-sided, I fear, and not like that intended by Myford.

CotswoldsPhil

.

Right-in-One, Phil

... it's actually about 90% of a Woodruff Key

... one end is missing; but I don't want to contemplate how that might have happened.

Interesting times ahead, I fear.

MichaelG.

Another way of preventing screws from working loose, while retaining the ability to adjust them, is to put a dab of low strength adhesive on the thread before fitting. After curing, the screw can be moved but retains a tight fit and will not vibrate loose. I use bearing strength loctite and this works well on gib screw threads. Don't be tempted to use high strength retainer like loctite 603 or you will never get the screw to move.

Doug

If a woodruff key is no longer available, you can always make one, with minimal "hand crafting".

With a piece of round bar (silver steel?) of the correct diameter, part off to the correct width (thickness), and hacksaw/file a flat until the key is the correct depth.

(Alternatively, if you know what the correct depth is, make the flat before parting off.

Deburr, and voila!

At least, that's how my son in law's circular saw was repaired when he sheared the key on the spindle.

Howard

Are you sure its not a standard parrallel key the shaft doesn't look deep enough for it to be a woodruff key?

as you know woodruff keys are semi circular and are usually twice as deep as they are wide, the length being what ever it needs to be

cheers

It's a woodruff key, Myford part no 700002 (there are two of them on the spindle) that has obviously been displaced when the headstock rear gear/collar was installed, at some earlier time. The perpetrator must have thought it lost, so made a replacement as Michael describes. I can see exactly how this might have happened, although the tumbler gears being misaligned with the headstock driver gear should have raised an alarm when everything was refitted.

Myford's instructions are quite specific about ensuring an even load on the inner races of the annular contact bearings (you can just make out some identification on the inner race in the photo) by only loosening the screwed adjusting collar's locking screw by just enough to allow it to be turned by hand. As shown, when reassembled, the force applied to the inner race through the misplaced woodruff key would not be as Myford intended.

Thanks, Phil

That's saved me the bother of explaining.

MichaelG.

Michael, my pleasure, all learned when I changed the bearings on my Super 7 a couple of weeks ago.

Cotswoldsphil