Thread: Micrometer "feel"

Originally Posted by cmailco

Only thing I'd add is that developing a method of consistent measurement is key, regardless the type of measuring tool.

Absolutely essential.

- Leigh

Originally Posted by The real Leigh

Normally you hold a mic in the palm of you right hand with the little finger outside, two fingers through the middle- Leigh

I was trained decades ago and have since used the little finger to hold onto the frame. I never even considered using another method and in years of using mics in front of hundreds of customers, never once was I corrected. In pantomiming the two positions just now it seems the little finger in the frame allows for more range of motion.
I'm not trying to be argumentative... just trying to learn something new to me.

I'll add a third way of holding a micrometer that's small enough to operate with one hand: Ring finger curled through micrometer frame, middle and little fingers straight, and thumb & index finger turning thimble.

My thumb and index finger are too short to reach a friction-clutch sleeve comfortably when the micrometer is more than about half-way open, so I end up grabbing the smooth portion of the thimble about half the time. Works fine after developing a consistent "touch".

Tight enough to hold a gage block from slipping out under its own weight. Loose enough to move easily between the faces.

Originally Posted by John Garner

I'll add a third way of holding a micrometer that's small enough to operate with one hand: Ring finger curled through micrometer frame, middle and little fingers straight, and thumb & index finger turning thimble.

My thumb and index finger are too short to reach a friction-clutch sleeve comfortably when the micrometer is more than about half-way open, so I end up grabbing the smooth portion of the thimble about half the time. Works fine after developing a consistent "touch".

here is a pic of what is described

Yeah, there are lots of different ways to hold a mic.

The technique that I described was in use when I apprenticed 50+ years ago, and I've generally followed it.

The bottom line is consistency.

Regardless of what technique you use, you should consistently get readings
within .0001" (assuming tenth-reading mics) on a gage block.

If you do, then your technique is working for you, which is all that matters.

- Leigh

Quick update from the OP. Thanks for all the good info in this thread, it really helped me out. What I found with my mics.

1. Lube, a couple of my mics were definitely dry, a well placed drop of lube greatly improved the sensitivity.

2. I also found forcing myself to ignore the scale while adjusting the thimble really improved my consistency. I believe my brain was always trying to achieve the correct reading regardless to the amount of pressure on the thimble.

3. After figuring out #2 it was easy to see which of my mics were consistently off against the standards, and by how much. Slight adjustments were made, now they all read zero against the standards first try consistently. Most importantly, when measuring a unknown dimension now I can trust the result.

Jtommr - What you have learned here in the past couple of days has taken some people YEARS to realize. Kudos to you for not being afraid to ask a question, and for taking the information given and applying it successfully. (And also for thanking those that were willing to share!)

In aid of avoiding the tendency to 'find' the 'correct' measurement, I use my thumb to turn the thimble, with my thumb over the measurement reading area.

Can't adjust if you cannot see the lines. Once I have my feel, then I can look at the marks to see if the measurement is consistent.

The instructor that taught me, taught that the thimble was to be used, and that it was to be three clicks, no more, no less. I can relate to the idea that it is a impact hammer of sorts, and that the thimbles vary from mic to mic, but if it gets the correct measurement each time, and is consistent, then it works.

Use what works.

Cheers
Trev

Originally Posted by Jtommr

I have a set of Mitutoyo micrometers with .0001" resolution. They are the most basic model, no lock or ratchet. In order to get accurate, repeatable results at the finest resolution, I'm trying to develop a sense of feel for their use.

What is the correct amount of pressure to apply to the part being measured? How much is too much?

Instead of advice I have a question because I find your post unusual

How old are these micrometers and do you have a type number for them?

I'm asking because I've never heard of Mitutoyo micrometers without a ratchet. A picture would be great too

We can call this professional curiosity.

Just for the record, normally the measurement pressure for a Mitutoyo (and most others brands) micrometer is given as 5 - 10N in their catalogues.

Originally Posted by Gordon B. Clarke

Instead of advice I have a question because I find your post unusual

How old are these micrometers and do you have a type number for them?

I'm asking because I've never heard of Mitutoyo micrometers without a ratchet. A picture would be great too

We can call this professional curiosity.

Just for the record, normally the measurement pressure for a Mitutoyo (and most others brands) micrometer is given as 5 - 10N in their catalogues.

The 6 piece set (103-933) was purchased used, and the age is unknown?? Individual model numbers range from 103-113 - 103-118

Originally Posted by Gordon B. Clarke

Instead of advice I have a question because I find your post unusual

How old are these micrometers and do you have a type number for them?

I'm asking because I've never heard of Mitutoyo micrometers without a ratchet. A picture would be great too

We can call this professional curiosity.

Just for the record, normally the measurement pressure for a Mitutoyo (and most others brands) micrometer is given as 5 - 10N in their catalogues.

According to Mitutoyo's "Product Fundamentals" brochure (page 2), their micrometers are available with a "plain thimble", a "friction thimble", a "ratchet stop", or a "ratchet thimble".

http://www.mitutoyo.com/pdf/2016_ProductFund.pdf

Originally Posted by Eric M

According to Mitutoyo's "Product Fundamentals" brochure (page 2), their micrometers are available with a "plain thimble", a "friction thimble", a "ratchet stop", or a "ratchet thimble".

http://www.mitutoyo.com/pdf/2016_ProductFund.pdf

Excellent link and first time I've seen it I'll have to take the time to read it through.

Of the 5 types shown though the plain thimble one isn't exactly the one being praised or recommended except re price.

To take the quote from the link:

"The plain thimbles advantage is it’s reduced cost. The disadvantage is it’s reliance on operator “feel” to ensure accurate measurements".

Still, to each his own and as the OP now feels happy, then everything is fine

If you are at work why not ask your inspector to check your micrometres, after all what these guys say often goes see if they'll check them for you, then use a slip guage or standard and see if you can get the micrometre to match it.

However dont look at the thimble as you measure i have been told because you can influence the reading and over tighten it which wont do anything for your feel. And for the correct feel you should just feel pressure under the anvils and then give the workpiece a slight 'wiggle' to ensure you are on the highest point.

Hope this helps.

Originally Posted by geoinc

However dont look at the thimble as you measure i have been told because you can influence the reading and over tighten it which wont do anything for your feel. And for the correct feel you should just feel pressure under the anvils and then give the workpiece a slight 'wiggle' to ensure you are on the highest point.

Hope this helps.

This might get this thread locked or my post deleted but are any of those advocating/recommending the touchy, feely aproach to micrometer measurement under 60 years old?

There are things I learned 50 years ago that are still good to know but the world has changed and mostly for the better.

Is there a machinist here (under 50) that measures daily with a micrometer at their machine and doesn't use the ratchet?

I can hold a 0-1" micrometer with one hand and measure as shown but only do so when I'm showing off it's also rather difficult when the micrometer is over 1-2".

Gordon

Gordon....I'm 30...been running a mic for almost 10 years.....my mics have ratchets or thimbles, I hardley use them unless something seems fishy and I have to double check my readings (odd shaped materials) :-)

Originally Posted by xdmp22

Gordon....I'm 30...been running a mic for almost 10 years.....my mics have ratchets or thimbles, I hardley use them unless something seems fishy and I have to double check my readings (odd shaped materials) :-)

I always, always use the the thimble, and the ratchet for bigger Mics. They aren't there to make you think you have a good measurement they are there to make sure you DON'T over tighten them. Any Mic can be qualified at any time on most realistic diameters or planes.

But haven't you just proven Gordon's point, by saying you only use them when you are questioning the measurement? That would tell me that when you are un-sure you use them, and when you are confident you don't.

Robert

Originally Posted by litlerob

snip

But haven't you just proven Gordon's point, by saying you only use them when you are questioning the measurement? That would tell me that when you are un-sure you use them, and when you are confident you don't.

Robert

I just use them as a backup or reassurance.....like when you take a few .020 cuts on a lathe and measure, it takes .020 off each tiime....then you take another and it only takes .018 or takes .021....was it the tool? The mic? The user? The gremlins in the machine?

Measure once with your "feel" once with the ratchet/thimble...numbers match? Cool...its not the user or the mic....kind of like asking another guy in the shop to double check you....

Originally Posted by xdmp22

Gordon....I'm 30...been running a mic for almost 10 years.....my mics have ratchets or thimbles, I hardley use them unless something seems fishy and I have to double check my readings (odd shaped materials) :-)

I'm not sure if it's what you intended to imply but I read that as if you only use the ratchet when in doubt and want to make sure you're measuring correctly?

Originally Posted by litlerob

I always, always use the the thimble, and the ratchet for bigger Mics. They aren't there to make you think you have a good measurement they are there to make sure you DON'T over tighten them. Any Mic can be qualified at any time on most realistic diameters or planes.

But haven't you just proven Gordon's point, by saying you only use them when you are questioning the measurement? That would tell me that when you are un-sure you use them, and when you are confident you don't.

Robert

Sorry. Replied before reading your post

Gordon