I can't read a micrometer vernier

[Land Owner]

You read that right. I am not a machinist. I have zero experience reading a 1" micrometer vernier and it is driving me insane.

I have a Starrett No. 231-F with a complete rotation, 25/1000th, "course" dial graduations and 10 vernier marks.

At "0" (fully closed), the "3" and "12" of the course graduation are aligned with "0" and "10" respectively on the vernier. Obvious to even the most casual observer, this is 0/1000th of an inch (0.000").

One complete revolution of the course graduation, aligning with "0" as above, is 25/1000th of an inch (0.025"). Four (4) complete revolutions reads 0.100" (100/1000th of an inch). If it was all this "simple", I would "get it".

It gets confusing (to me) when the rotation is some intermediate mark. If the micrometer comes to rest at (say) 0.3" plus 23/1000th, plus 4.5 on the vernier (between 4 and 5 but not on either), what is that (0.32345")?

I lack confidence in reading a micrometer. I have a "direct reading" caliper, but often a caliper is not the right tool.

Lord, don't even discuss the estate purchased 1" Chicom direct reading digital mic I have with only 5 demarcations on the vernier. I am lost in space with that one.

[Dusty Bannister]

This looked like a pretty good explaination and the photos are clear enough to see what is being described.

https://www.instructables.com/How-to-Read-a-Micrometer/

[kenton]

The vernier only measures tenths of a thousandths (.0001) or a tenth to machinists. To use the tenths vernier you take your standard measurement to thousandths, (.001, .354, .787, etc) then look at your tenths vernier and the number that is closest to lining up with a line on the thimble is the value you add to your dimension. (.0012, .3544, .7869, etc)

Here is another good video:
https://www.youtube.com/watch?v=j0ARvWwMZX8

Lots of other good content too.

I reread your post and realized what you were asking, yes if it is splitting the difference between lining up between, say 3 and 4 you could say .32335. I will caution you with the fact that by rotating the mic you can make a range of numbers seem to line up on the tenths vernier. Also it may be sacrilege to say, but the tenths vernier on a standard micrometer is a hair better than guessing the tenths value by looking at how far the thimble is from lining up. If you really need tenths accuracy you need better equipment than a standard mic. So claiming to be "splitting tenths" will be viewed as a bit dubious by most machinists.

[C.F.Plinker]

When my mic is fully closed the The "0" on the coarse graduations (on the thimble)should line up with the "0" on the vernier. I don't know how the Starrett adjusts but on my mic there is a small hole in the sleeve where the vernier numbers are. There is also a small wrench that can be used to turn the sleeve so that the "0" on the thimble and the "0" on the vernier line up when the mic is fully closed.

Lets say you are measuring a boolet and the mic shows that it is between .358 and .359 inches. It can help if you lock the thimble in place when you do the next operation to keep from rotating the thimble. As you look at the vernier marks and the thimble marks they will not match up. Except for one pair. Look down the vernier line to the vernier graduations. This digit is the "tenths" reading. Lets say it was "4'. Now the boolet diameter is .3484 inches.


EDIT
I found a picture of the Starrett 231 and it is different than my mic. The vernier is offset and is as you described in the original posting. So your mic does not need any adjustment. To read the vernier and get the "tenths" reading look for the vernier line that matches the line on the thimble. This is the "tenths" reading.

From the original post:
"It gets confusing (to me) when the rotation is some intermediate mark. If the micrometer comes to rest at (say) 0.3" plus 23/1000th, plus 4.5 on the vernier (between 4 and 5 but not on either), what is that (0.32345")?"

Yep.

[kevin c]

Thank goodness I'm not the only one!

Every time, I gotta think it through: "First number is tenths of an inch, four little lines to the next number is a quarter of a tenth, oh yeah, same as the twenty five gradations on the twirly thingy so twenty five, er, thousandths. And, um, then the best lined up line on the, uh barrel? Must be, lessee, what's left, oh yeah, ten thousandths. Okay, zero point tenths plus number of little lines times twenty five is hundredths, no dang it, thousandths, so two more decimals, whoops, forgot to add the twirly thingy number (am I still on thousandths?) plus lined up line is ten thousands, drat, forgot to throw the lock, start over...)...

Oh, forget the ten thousandths, where's my digital caliper...

[smithnframe]

How long have you been handloading? My Dad taught me to read a micrometer/vernier caliper when I was 12 years old. The next year in metal shop I was the only kid who could read a micrometer.......thanks Dad!

[Land Owner]

Been reloading for 30+ years, bless your heart and thanks for asking. Good on your Dad for teaching you.

I KNOW how to read a caliper. I AVOID the micrometer, though through inheritance and an estate purchase, I now own two of them.

[pworley1]

https://aws.linnbenton.edu/krolicp/M.../practice.html This will help.

[pworley1]

https://www.stefanelli.eng.br/en/vir...nch-simulator/ Or this one.

[country gent]

There is a big difference in reading a mike and be proficient with one.

Mikes require a feel to use accurately this is learned over time and use.

gauge blocks, pins are best but bullets dowels bolts in assorted sizes will work. Sit down and measure known items Mot mikes come with a short sheet on reading them, if you can find the same size part and measure it makes the description clear.

[farmbif]

I gotta believe there are all kinds of instruction now a days on internet on how to use micrometer. in practical use in the past boring and honing cylinder holes I've found that using a high quality starrett, mityoto or brown and sharp veneer gauge to be accurate as a micrometer for what I was doing. in fact lately I've been thinking of selling off some of the stuff in my Kennedy boxes since its been years since I've used them and I guess its that time in life for me to downsize

[farmbif]

I might add that with a micrometer the first thing when taking it out of case is open it up and use a standard to check it, without checking it with a standard you have no way of knowing if it needs adjustment to zero it out.
for ease of use a modern Starrett or mityoto digital 6" veneer gauge is the cats meow, you won't regret the investment into highest quality tools, has been my experience anyway.

[lotech]

I use a micrometer pretty regularly when handloading, particularly with cast bullets. Frequent routine use will aid in reading the scale without difficulty. I use a Browne & Sharpe but others will probably work just as well.

[Char-Gar]

Couple of tips:

1. Keep the faces of the mic clean. Close them on a sheet of clean paper and draw the paper out. Do this a couple of times.

2. Mics do require a feel, but most good makes will have one or more types of gizmos to ensure uniform pressure. (Friction Thimble or Ratchet) these can help.

3. They do make digital readout mics that are not electronic, or at least they did. I keep a Starrett 216 close at hand and is great for most reloading uses. I have three or four other Starretts that I have picked up over the years.

4. If not dropped or used as a C Clamp, they will last a lifetime. A quality tool is the best use of your money.

[rbuck351]

After using a standard to set your mic to "0" or in the case of a 1" mic closing it all the way and setting it to "0" you simply read the mic. Large lines are .100 and are marked 1,2,3 etc. The smaller lines in between are .025 and are not marked. The numbers 0,5,10,15 on the turning part of the mic are .001 or thousands. When the numbers on the turning part do not align with the "0" line on the vernier you search the vernier for the closest line up and add number of ten thousands.
Yes, the .32345 is correct but you would have to be very good and your mic would have to be very good and adjusted very well to expect that number to be accurate to .0001 and expecting a common mic to be accurate to .00005 is not reasonable.

Also you should clean the faces of your mic before setting to "0" and before measuring anything. Put a clean piece of printer paper between the faces and close gently then pull the paper out. Then check and set "0".

[Duckiller]

Get a digital mic! Even if you have to buy batteries occasionally they are easier to read.

[rbuck351]

I have about a dozen mics and three or four dial calipers one of which is digital. I rarely use the digital as it normally has a dead battery and I can't remember where I put it last. I just don't trust them. Yeah even the cheap HF one I have is accurate, but I still don't trust them.

[jmorris]

[lightman]

Don't feel bad, its something thats got to be learned. Its fairly simple but you still have to learn. If you don't read a vernier scale pretty often it takes a little getting used to. If I go for a while between uses I'll start with a practice run on something with a known diameter, like a jacketed bullet.

[Land Owner]

https://www.stefanelli.eng.br/en/vir...nch-simulator/ Or this one.

I looked at all of the referenced links - THAT is a good one for practice!