How do you use a micrometer?

[GrifterGuru]

When in doubt, read the instructions; I never did ---

True enough, but when taught by a 35+ year engineer, you tend to listen and not question "why".

 

[MrWhoopee]

And we are told that we should only use 3 clicks of the ratchet to assure constant readings, I have not heard how to use the similar friction thimble, all of mine are ratchet type, but I rarely make use of that feature, relying on feel only.

Same here. I bought all my mics with ratchet stop, never use 'em.
For reasons that I can't explain, now that I'm just a hobbyist I do almost everything with my Tesa dial calipers. Even press fits.

 

[skogkatt007]

I won't be cheated out of a proper reply.

So how hard do you clamp down with your Tesa caliper? If you say not too hard I might scream.

 

[mmcmdl]

Ratchet ? We don't need no stinkin ratchet !

 

[Bone Head]

Ah; but wait; there's more!
Is your anvils of your mic clean? Use a clean piece of paper with your anvils tightened down on it (2 clicks please) and gently pull the paper clear through.
Is your mic properly lubricated? Including the ratchet if so equipped?

 

[OTmachine]

Heat from milling or lathe work can definitely cause things to expand by a few thou.

Coefficient of expansion is a Good thing to know.

 

[Mini Cooper S]

I first started using mics in the late 1960's. Not many mics with ratchets so I learned to use feel. The first set that I purchased for myself in 1972 had ratchets, I never liked them, always felt that I got more consistent results by using feel. I always set my mics for very light feel as this allows for less gripping of the part, especially with carbide faces. Another thing that I do is I never look at the mic when I am measuring so as not to influence my measurement. Also I measure three times and compare answers, if I get three in a row the same, I'm good with the measurement

Richard

 

[Canus]

While use of the ratchet may give you consistent readings they MAY not be accurate readings. Test the ratchet function by measuring a known dimension, such as a gauge block. If use of the ratchet gives an accurate reading then go with it. If not, at least you will know how off your reading is and you can compensate. Personally I never use the ratchet and go by feel.

 

[pontiac428]

Methinks that, at least to a point, the method you use to close in on the work, whether it's some clicks or snug the way you like it, should be the same as the method used when zeroing the mic on a calibration block. You can't change the rate or the span, just the zero point and preload. Without going needlessly down into the weeds of the mechanism, that should be the basis for our purposes.

Of course, I could happily chat with @Bone Head about it all day, I cut my teeth in a multi-ISO accredited lab, but that level of depth had a defined purpose. In my shop, tenths are a nice target, but 99.9% of the time the pursuit is esoteric.

 

[RaisedByWolves]

And we are told that we should only use 3 clicks of the ratchet to assure constant readings, I have not heard how to use the similar friction thimble, all of mine are ratchet type, but I rarely make use of that feature, relying on feel only.

"By feel" is how I was taught as it crosses over to many different mic designs and measuring methods.

Ive seen guys sneer at people using the ratchet, as while it is repeatable, it is not as accurate as going by feel as it can tweak the frame giving a false reading.

The friction thimble being the better option of the two.