Micrometer Blues

It will work fine, but seems a bit pointless, if the thimble is close to zero, then it's close to a fiducial line, even if you can't see it.

If you move it 'right' to show when it's creeping up on a line from the left better, won't it have the opposite effect and make it harder to judge when approaching a line from the right?

This style of construction has no adjustment for positioning the thimble on the screw, it may be preferable to alter the sleeve rather than the thimble but I would be disinclined to do either. Reading the mic in the position shown the line is partially obscured but I tend to hold a small mic with my little finger through the c frame and third finger clamping it in my hand, thumb and forefinger to turn the thimble. In this position you tend to have the thimble vertical and looking into the joint between thimble and sleeve and the lines are much more visable. Moore and Wright mics can adjust the position of the thimble as it is clamped between a nut and locking screw so you can choose where the lines show.

Mike

Well, many thanks as always to all those who took the trouble to reply, it's been hugely entertaining watching this develop over the course of the last 24 hours or so.

There seem to be three schools of thought -

1- don't fix what aint broke,

2 - you're going to make it a whole worse

3 - I've been there too.

The back story is that I bought this mic' back in the late 70's, and have hardy used it since, because I've never learnt to read it reliably. I'm not sure I understand why the same is not true of almost all of the imperial mic's in my toolbox, but this one seems particularly obnoxious. To me.

I was sorting twist drills yesterday, and took to this one to see if I could get on with it, and decided the answer was no. So I might as well modify it as throw it away. Yes, I completed the job using a digital mic', but there are times when a tidy little thing like this is easier to use.

Tubal Cain's video gives me some hope that I'm not going doolally - well probably I am but it's nice to have company - so thanks for that link, and particular thanks to Mike Poole who seems to have dismantled a perfectly good identical mic' just to show me what the internal arrangement is, which was my original question. I'm still humming and hawing over whether the game's worth the candle - but I've just worked out how to get the sleeve off so that gives me the option of taking a lick off the heel of this instead of the thimble. Less likely to get grinding dust in the measuring thread.

I'm keeping schtum about whether my metaphorical angle grinder is the way to do the job. I never said I was going to plug it in!

I've been chuckling all afternoon about the debate between accuracy and legibility. My warped sense of humour finds in this a direct analogue of the inability of the newspapers to resolve the same.

Regards to all

Simon

Hi, I've had the same problem with a Moore & Wright 0-13mm mic.

Very difficult to see the markings without a magnifier and then had to look at it at a slight angle from the left.

Well this morning I've cured the problem by removing the sleeve and taking a smidgen off the head end of it while holding it in my collet chuck and then refitting it back onto the mic and placing the datum line in a more central position. I then had to loosen the screw holding the thimble and tuning it up slightly to bring the zero mark back in line with the datum line when the mic was closed to zero.

I can now read the mic clearly seeing the marks just with my normal glasses on and looking at it face on. Much better.

Personally I don't see how this can affect the accuracy of the mic, because there has been no interference with the measuring components. In my mind it is no different to shifting a zero point on a DRO.

Regards Nick.

How about removing the thimble and mounting it in the mill with the 0 facing upwards, then with a small end mill (1.5 - 2mm ) milling a hemisphere into it in line with the zero line. This will allow you to see where you are without too much hastle. You could even do this by hand with a file.

Regards.

David.

Err next time engage brain! This will only work at one point per turn of the thimble. Doh!!!

David.

Before everybody starts machining their mics, check that it is not adjustable like this Moore and Wright. The thimble position can be adjusted by the black nut shown on the spindle here, the thimble is released by unscrewing the ratchet. This probably doesn't apply to Nicks 13mm mic as it is a compact thimble and likely to be like the Starrett I pictured.

Mike

Hi Mike, my 13mm one has a cone on the ratchet that engages into a corresponding split cone in the spindle, which opens it out into the hole on the one piece thimble.

Regards Nick.

Seems like it's Easter Egg Holiday Micrometer Modifying Friday!

In between toasting hot cross buns, I too have been modding my micrometer.

Here's the sleeve dismantled:

The brown crud on the inner is dried oil. Carburettor cleaner is wonderful stuff...

And here it is after taking 8 thou off the LH end of the scale sleeve and re-assembling it.

I did it by holding the sleeve into a 12 mm collet and popping it into the T&C grinder so I could control the amount of metal removed. Is it fixed? - time will tell!

Now, why has the toaster caught fire.....

Since we are talking metric mics, better to have written "0.2mm off" !

You can solve the real problem without affecting the notional 'accuracy' using a chain-saw file. Remove the barrel (just unscrew it all the way) and carefully file a notch in the edge at the zero position. Don't go mad - leave enough of every scale mark so that no confusion there can arise. Tidy up any burrs with wet & dry wrapped round the same file. This will only give you the extra visibility around the zero position, but that is the only place where confusion of this nature can arise - isn't it?

Or have I joined the ranks of 'don't understand' ?

Cheers, Tim

Hi Tim, I think I prefer both Simon and my solution, looks much neater me thinks.

Regards Nick.