Thread: Mitutoyu Micrometers - new to me, refresh and questions

I don’t own any micrometers... until now

A chap locally was clearing his old measuring equipment and they caught my eye. Managed to snag a 1” and 2” and now I’m doing what I always do... pulling them totally apart.



The 1” has an analogue digital readout (metric) and imperial shaft. I have it completely apart and have a few questions.

1. What’s a good oil to use now I’m putting it back together again? 3-1?
2. My 2” has a really nice ratchet feature and I can’t work out if the 1” is supposed to have something similar. The end barrel has a locking mechanism for 1 way but spins freely the other way. Is that how it’s supposed to work?

Hi Neevo,

Do not use 3-1 oil, it goes gummy over time and will glue the threads, I just wipe my mic threads with oily fingers SAE 5-20 motor oil, the old non additive variety. Actually the same stuff that I use on the lathe and mill.

Hydraulic oil is as good as any.

Ok great thanks. Can you help with how the ratchets should work? I was always under the impression they were a slip device to get the right tension when tightening but mine only seem to spin one way and lock the other. Almost like a quick way to undo them, not a tightening solution.

Neevo
I have a set very similar to yours except mine are full metric. Barrel and thimble are vernier type.
Mine has a std ratchet on the end. What I think is the end in your picture looks different to mine.

mic.jpg

Peter

Yeah my 1-2” one has the same ratchet but the 1” has a different device which uses a coiled spring to lock the spindle.

Is it a loosening or tightening device the ratchet?

This is the 1-2” and the end cap is separate and spins with a solid click:



This one the end cap is solid and screws on to the large knurled section. The whole knurled section spins:

I don't think I've seen one like that before.
My ratchet ratchets to tighten (supposed to be able to give a uniform feel) and locks to loosen.
I prefer to just go by feel. When I was an apprentice we were taught not to trust the ratchet as they can vary between mics. So instead we were taught to learn the "feel". Of course everyone's "feel" can be different as well.

peter

That’s always what I thought the ratchet would be for. If my ratchet spins without anything in the micrometer does that mean the thread clamp is too tight?

Both have done this when I go them.

Hi Neevo,

If there is nothing in between the mic jaws then the ratchet should just turn the spindle, when it meets the work it should just click. If it clicks without moving the thimble then the thimble is too tight.

The other one doesn't have anything to adjust the tension, so it is just feel to get it right.

The 0 - 1" is a friction thimble. It slips when the correct force is applied when measuring. When you loosen the thimble it locks and opens. Generally a higher priced option and nice to use one handed because you can easily turn the barrel close in rather than reaching the ratchet. For presidential hands. I preferred friction thimbles over ratchet types when I inspected.

Pete

I opened them up again and released the tension on the nuts and got them to both work with slipping. Still need to dial the 1” one off a bit more I think.

They’re beautifully made items. Very exciting to have some Mitutoyo in the shed

Should the 1” handle have some grease in it? Without any grease I have to have the tension backed right off. However if it had some moly grease or similar I can imagine that would provide enough drag to offer the required level of tension to work.

Currently I have the tension dialled back so much it seems to loose and also even then there isn’t enough tension to close up the final 0.01mm without having to push the handle in to the spindle a little.

Neevo, I have a similar micrometer, but it has the ratchet mechanism and when taken apart it had a very light grease inside, so maybe a small dab of something like vaseline would be suitable. Alan.

ratchet.jpg

I’ll give that a go. Thanks

Took the handle off the 1” micrometer and filled the space between it and the barrel with moly grease. It didn’t take a lot but it’s now added enough drag to work perfectly


https://youtu.be/p7ttjrbAki8

Nice to see the dials all lining up with zero too

This will be a mega useful tool for me. Largely because I work in metric but my lathe is imperial. This will give me both options when measuring and know what I need to take off to get it on spec.