Reading Micrometers: Our return to this website...

[Ray C]

Hi All...

I had an offline talk with Tony and Nelson because I felt this was a nice site and wanted to contribute. The idea came-up to create a bunch of "Sticky" reference Metrology sections starting with the basics of things helpful to a newcomer hobby machinist. So, how about if we tackle the subject of basic, non-digital Micrometers? Perhaps we could start that with nomenclature then, move on to how to use and read it (including tenths) then, move on to tightening techniques (with or w/o ratchet), how to check/adjust calibration, effects due to temperature, proper care, how to identify problems -and of course, any topics you feel are helpful including any good stories about your success and mistakes with mics. (and in all honesty, some of these topics are things I could stand to learn about myself)...

Well, what say you? Who will be the first to post?

Regards

Ray

 

[rebush]

Ray: Sounds like a great idea. Calipers are easy to use but to me they don't have the accuracy of a micrometer. There are a few online sites to teach a person how to read a micrometer. Complete with example that you enter the measurements. Roger

 

[Bill Gruby]

A picture is worth a thousand words. These are the two most used, the outside and the depth mikes.

"Billy G" )

 

[RandyM]

Ray: Sounds like a great idea. Calipers are easy to use but to me they don't have the accuracy of a micrometer. There are a few online sites to teach a person how to read a micrometer. Complete with example that you enter the measurements. Roger

Great tease Roger, could I coax you into posting the links to those sites? I think that would be a big help. Thanks.

 

[Metalmann]

I've seen some trainees who would use a mic like a c-clamp.

That "Machinist Feel" just takes time, and experience.

In high production environments, everybody should be taught the same feel.

Don't rely too heavily on ratchet type mics, the ratchet/friction; may not be set correctly.

 

[Bill Gruby]

Great tease Roger, could I coax you into posting the links to those sites? I think that would be a big help. Thanks.

Here is a good one Randy.




http://www.linnbenton.edu/auto/day/mike/read.html


"Billy G" )

 

[RandyM]

Here is a good one Randy.

http://www.linnbenton.edu/auto/day/mike/read.html


"Billy G" )

EXCELLENT! Now that is a great post. Thank you Bill.

 

[Tom Griffin]

I used to be a "shop teacher" and used the dollars, quarters, cents analogy to teach newcomers how to read the micrometer. It's just a matter of adding up all the change; the numbers on the barrel are dollars, the marks in between them are quarters and the numbers on the thimble are cents. If it's a tenth reading micrometer, you just have to use your imagination a bit and add tenths of a cent to the total amount.

Tom

 

[sanddan]

Thanks Bill, I bookmarked that one.

Dan

 

[Ray C]

Yes, that link provided was very nice but I don't know if we can count on it being available forever. I'll make reference of it in the first pass of our tutorial but will also draw-up some of our own diagrams.

Here's a few more questions to toss out...

What's your technique on how to tighten/tension the spindle? -Firm until it stops or stop at first touch? -A pre-defined twist of the ratchet?


Also, what are your thoughts about the effect of temperature on measuring things? I recently bought a couple brand new mics (4 & 5 inch) which came with calibration bars. Using their respective calibration bars, both of them showed a 0.0005 error. I can only presume it had something to do with my shop being about 60 degrees at the time....

And here's one for you... Is there a way to fix a mic that zeros when shut but is off a bit when checked against a calibration bar?