Micrometer ratchet stop

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Micrometer ratchet stop

This topic has 6 replies, 5 voices, and was last updated 30 June 2010 at 17:48 by Gray62.

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28 June 2010 at 15:27 #16560
Gray62
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@gray62
Moore & Wright micrometers
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28 June 2010 at 15:27 #52977
Gray62
Participant
@gray62
I have a couple of Moore & Wright micrometers that need the ratchet mechanism repaired/replaced. One has the ratchet disk and knob intact but is missing the pawl and spring. The other is missing most of the mechanism.

Does anyone know if parts are available from any source that might effect a useable repair on these, or have any suggestions as to a way forward.

I accept that calibration will be affected no matter what I do however, these are generally used for comparative testing and supreme accuracy is not essential. Once I can repair, I wil then invcestigate a suitable calibration method
28 June 2010 at 21:06 #52981
Jim Whetren
Participant
@jimwhetren72358
Hello CoalBurner,

Many years ago I aquired a couple of mikes in pretty much the same state.

I made a replacement pawl for one, and when it was all working, made a duplicate mechanism for the one without.

The re-calibration was a piece of cake, just rotate the scale till it reads zero.

I will check if mine are M & W or Starret, as they are imperial they don’t get any use.

Jim
30 June 2010 at 08:36 #53016
Eric Cox
Participant
@ericcox50497
The cost of the spares may work out more than a second hand mic. of e-bay, about £10.

As for calibrating, ensure the anvil faces are clean, close the mic. up and see if the zero is lined up, check alignment again at 1.00″ (assuming it’s a 0-1″ mic.) using a 1″ slip gauge.

If there is a discrepancy, the barrel can be rotated. On the back of the barrel opposite zero on the vernier scale is a small hole. Using the “C” spanner, if you’ve still got it, rotate the barrel to align the vernier scale.
30 June 2010 at 09:47 #53017
Terryd
Participant
@terryd72465
Dear Coalburner,

I agree with Eric, just a quick glance at eBay will show how cheap they are. See here for M&W Mikes. Forget the sentiment, dump or sell them for spares and go for a decent one. It’s not worth the effort these days.

Just my opinion.

Terry

Edited By Terryd on 30/06/2010 09:47:50
30 June 2010 at 11:16 #53019
Keith Long
Participant
@keithlong89920
With careful twiddling the rachet isn’t essential anyway. I used to use mics a lot at work and found you quickly develop a feel for when you are making contact with the job. If you are using them as comparators then it implies that you will be checking both items in succession or over a very short time span. You should be able to get consistent readings to within a couple of tenths quite easily without the rachet.

Keith
30 June 2010 at 17:48 #53023
Gray62
Participant
@gray62
Thanks for your replies,

Terry, understand where you’re coming from but I am against the current trend of a throw away society, if it can be repaired, then it should be. The sentimental or intrinsic value is of no consequence, nor is the ultimate value, the fact is that these are well made measuring instruments and have a value to me. I see any repair as a challenge, having repaired a number of clocks that were deemed by my local clockmaker as Beyond economic repair I value the challenge of repairing anything, and am merely seeking any advice from anyone who has undertaken similar repairs. the machining of the components presents no challenge whatsoever.

Keith, I understand what you are saying and I must admit, I don’t often use the ratchet as feel can be just as accurate, depending on how well the ratchet is set up. The point is. I want to restore these Mic’s to as near original condition as possible, thats most of the fun in engineering.

So, lets forget all the negatives, and throw aways and concentrate on the engineering aspect of this post.

with all due respect

Graeme
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