M&W Micrometer Lock

I seem to have lost the locking sleeve on my Moore & Wright # 966/2 1-2" mike. It goes where the arrow is in the picture. If someone with one could measure up theirs so I could make a replacement I would be most appreciative. I need the OD and pitch of the threaded part and the dimensions of the bore. I suspect the bore might be tapered to compress the split sleeve around the spindle thus locking it. Below is a pic of the mike and a cross sectional drawing of what I think the locking sleeve looks like. I suspect the thread will be 55 deg.

Thanks.

If everything goes as normal, as soon as I make a new one the original will show up in plain sight!

John

Edited By John Purdy on 10/02/2022 23:32:28

You have a PM..

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I guess the title is a bit ambiguous, Never thought of it that way when I wrote it. Sorry about that.

Maybe the moderator could change it to Micrometer Lock?

John

Edited By John Purdy on 11/02/2022 17:49:27

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There should be one on it's way..

So.. still some uncertainty about the thread..

..seems to be based on an 'Imperial'-sized part, but thread looks (under magnification) to be of 60* form and 0.5mm pitch with say 75% certainty - is the 9.87mm major D. intended to be a nominal 10mm?

The gauge was unbranded, but German-made.

Could it be 48tpi? ..possible, but I don't have the gauge to measure it..

I couldn't measure the large end of the internal taper with any certainty - the small end is given.

A spring steel 'wavy washer' is pressed over the thread and trapped in the groove behind, resisting all attempts to remove it.

I've described the knurl as 'Medium' - it looks somewhat coarse on the (small) component - for ease of grip, I guess.

Edited By DiogenesII on 15/02/2022 18:45:48

I used to have a boss called Mike Lock, a really nice chap. I often wonder happened to my old office colleagues (I worked for Lucas back in the 70's and 80's).

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Any relation to Mike Stand?

CG

Don’t forget the wavy washer that stops the lock unscrewing when spinning the thimble, maybe that’s the original fault??

As regards the fine thread. Considering that it's an imperial mike. is the thread likely to be 40tpi. there are normally quite a few on imperial mikes. Certainly I wouldn't expect anything metric.

Roy

John P. states that it's a 1 - 2" Mike, as seen stamped on it. If it really was made in (metric) Germany, the maker would have had to comply with the specification supplied by M&W. I think that rules out any possibility of the speculation of it being a metric thread. 1000 thou to inch, nicely divided by the commonly used 40tpi, = 50 turns from closed (zero) to full open at 1"and hence 50 div's on barrel. Same as Roy has just pointed out.

John

The thread on the collar is noticeably, and with no doubt, finer than 40tpi and coarser than 60tpi.. ..there are no pitches between these in the only sets of Imperial gauges that I possess.

The thread we were discussing is the locking collar, not that of the thimble, apologies for any confusion

Edited By DiogenesII on 16/02/2022 17:55:16

John,

Have you tried the "Bowers Group", who either own or distribute M&W products for spare parts?

Thanks Bo'sun, but DiogenesII had a spare and has very kindly agreed to send it to me. Once it arrives I will try and ascertain what the thread actually is so if someone else is in the same situation they will be able to make a replacement.  One of my imperial thread gauges goes from 4 to 80 TPI including 48,50,56,60,64, and 72 so one of them should fit. I can't see it being metric as it was bought in the early '70s, but then my Myford S7 from '76 has a mix of imperial and metric fasteners!

I should come clean as to how it went missing! When I was making my radial steam aero engine I was trying to measure a 2" dia. spigot close to a shoulder and because the locking sleeve extends out beyond the body of the mike I couldn't get the mike square to the shoulder to measure it. So I removed the locking sleeve, which enabled me to make the measurement, and I put it somewhere safe so I wouldn't lose it. Obviously I put it in a very safe place as I can't find it now!!!

John

Edited By John Purdy on 16/02/2022 18:27:39

I just received the locking ring from Paul. For anyone needing to make one I have measured it under high magnification (20X )and the thread is 55 deg., 50TPI, .388" OD. The bore tapers from .273 on the outside to .325 on the inside and the rest of the dimensions are as Paul has shown in his post I measured the angle by comparing it with my small 60 and 55 deg. threading tools which were ground on the Quorn so should be reasonably accurate.

John

Edited By John Purdy on 28/02/2022 20:26:42