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Reading a vernier Caliper

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  • Reading a vernier Caliper

    I've never used one of these. It's an old Masure I assume. Does anyone have a link on reading this puppy or care to help? I watched a couple of videos on Youtube but still haven't figured it out exactly. What is the accuracy, .001? The 1, 2, 3 etc. are 1/10th of an inch (.100)? About 1.150"? I'm not sure what the graduations are on the top and bottom scales, .021 on the top scale?

    Is there anything I can put on the scribe marks where they're wearing off? Seems to be a nice caliper.

    Last edited by Smokedaddy; 04-26-2013, 01:21 AM.

  • #2
    Cool, I have never seen a vernier with separately adjustable scales for the OD and ID jaws unless the difference was .1" or .2".

    On this unit both scales will have essentially the same reading + - .005 or so depending on the calibration. In this case the ID jaws are able to be calibrated separately from the OD jaws.

    Dave

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    • #3
      Try this and see if it makes sense.

      http://www.youtube.com/watch?v=S_zsEPIN1EI
      Good lighting and good eyes help.
      Steve

      Comment


      • #4
        So far you're doing good. on the main beam, each number is .100" each line between is .025" now go to the slide. These numbers are the individual thousandths. 1-25 that fall between the lines on the main beam. So on your 1.150 measuement the 0 and 25 lines on the slide line up with the lines on the main beam. If the measurement was 1.155, only the 5th line on the slide would line up perfectly with the line on beam and the rest of the lines on the slide would very from almost in line to not even close to lining up. If you have any Mic's with tenths read on the barrel it is read the same way.
        As far as accuracy, it depends more on the user and what kind of feel you have and whether you regularly check for wear on the tool. Some people say +or - .003 some say + or - .005 and any tolerance tighter to use a mic.
        Hope this helps you.

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        • #5
          That's pretty much it. You look along the 0 to 25 scale to find which of those marks lines up the closest with one of the markings adjacent to it. Looking at your bottom scale, you have 1 inch, plus .1 inch, plus two divisions of .025 inch, plus what looks to me to be the 1 mark- total distance between the jaws is then 1.151 inches. On the top scale, you have 1 inch plus .1 plus .025, and it looks like the 24 mark lines up best with the adjacent scale, so the distance from the outside of the upper jaws is 1.149 inches.

          There's a 2 thou difference in the readings- this is because the inside measurement jaws overlap by about 2 thou when the other jaws are fully closed. This is done so the inside measurement jaws don't overlap and tend to catch on each other.

          Now I have to look carefully at that again to see if the 2 thou difference is in the right direction- your upper scale should be reading about 2 thou when the jaws are closed, or in other words, if you were to read an inside diameter using the lower scale, the hole you are measuring would be 2 thou larger than indicated.

          There's nothing wrong with a vernier caliper if it's in good condition and you learn to read it. If you have a hole that you know it's diameter to within a thou, check it with that vernier to see if what I've said makes sense- I think you need to adjust the position of the small scales by the look of it. If the lower one is correct, in other words it reads 0 when the jaws are closed, then the upper one should be reading 1.153 right now-

          Couple more things- it looks like the scribe marks are still there, but the ink is gone from them. I would clean it with a solvent of some kind, then completely dry it and wipe a permanent marker across the marks. Follow that quickly by wiping to remove the ink on the surface. You should be left with ink in all the 'slots'. You can use black nail polish as well. Give it time to dry, then lightly oil the whole thing. Wipe off the excess and yer done.

          Other thing- once you see that it's possible to see the difference in how the markings line up, you'll understand that you can read it to a thou, and you'll see when you're between thous- if the markings were accurately placed and the caliper is not worn or damaged, you can use it to measure down to .001 easily. There is no guarantee that a digital caliper is more accurate, even if it will give a reading of half a thou. My vernier, which is almost identical to yours except I don't have the upper scale, matches both my micrometers better than any of the other indicators I have, both in distance and linearity. It's not an expensive one either, though it does pre-date the chinese carp.
          Last edited by darryl; 04-26-2013, 03:35 AM.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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          • #6
            Originally posted by doctor demo View Post
            Try this and see if it makes sense.

            http://www.youtube.com/watch?v=S_zsEPIN1EI
            Good lighting and good eyes help.
            Steve
            Well, I went back and watched the link I posted and it is NOT what I thought I found. It is for 128ths not thousandths.
            Guess I shouldn't be so quick to link.
            You did get some good information between My two posts at least.

            Steve

            Comment


            • #7
              Click on this link http://ecatalog.starrett.com/Default.aspx# then select page 84. It describes how to read both an inch and metric vernier. It has a 50-division vernier instead of 25, but the principle is the same.

              FWIW, the vernier scale was invented by Pierre Vernier back in 1643 or something. I find it interesting that something so old is still in widespread use.
              Last edited by SGW; 04-26-2013, 07:42 AM.
              ----------
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              • #8
                I have learned on one just like this, It was in mm. I had a old craftsman some where that was set up similar. Some years ago a friend brought me a mauser
                dail vernier, the problem it had was skipping the gear bar that controls the dail. Mauser does not make verniers anymore. It was not a very good tool sort of hurt there name

                Comment


                • #9
                  As far as the other part of your question, if the lines are actually engraved then you can use a product similar to this. http://www.markal.com/lacquer-stik/
                  gbritnell

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                  • #10
                    Originally posted by darryl View Post
                    There's a 2 thou difference in the readings- this is because the inside measurement jaws overlap by about 2 thou when the other jaws are fully closed. This is done so the inside measurement jaws don't overlap and tend to catch on each other.
                    Strange, this is the third time I tried responding, Oh'well. Anyway, thanks for all the help (everyone else too). I was able to get 10 thou feeler gauge in between the top jaws when the bottom was completely closed. Are you saying that I should adjust the knurled knob until I get 2 thou on the top, then it's ready to use?

                    -JWW:

                    Comment


                    • #11
                      Originally posted by gbritnell View Post
                      As far as the other part of your question, if the lines are actually engraved then you can use a product similar to this. http://www.markal.com/lacquer-stik/
                      gbritnell
                      ... I had this book marked once on my old computer and couldn't remember what it was called.

                      Thanks ...

                      Comment


                      • #12
                        Originally posted by Smokedaddy View Post
                        Are you saying that I should adjust the knurled knob until I get 2 thou on the top, then it's ready to use?
                        -JWW:
                        I was wondering before what that knurled knob is for.

                        Usually it is for a fine adjustment feature but that requires a separate clamp on the beam to push or pull against. On closer inspection it looks like it actuates the brake to lock the slider on the beam?

                        As for calibration, you need to find an accurate hole of known size. Set the internal jaws to this hole, then without moving the slider, loosen the screws that hold the vernier plate for the internal reading. There should be enough slop in the holes to allow you to shove the vernier plate sideways to the correct reading, then tighten the screws.

                        The OD jaws can be set by closing completely and then adjusting the respective vernier plate to read zero.

                        Dave

                        Comment


                        • #13
                          Originally posted by becksmachine View Post
                          I was wondering before what that knurled knob is for.

                          Usually it is for a fine adjustment feature but that requires a separate clamp on the beam to push or pull against. On closer inspection it looks like it actuates the brake to lock the slider on the beam?
                          Dave,

                          At one time I too "thought" that the knurled knob was for fine adjustment.

                          -SD:

                          Comment


                          • #14
                            Originally posted by Smokedaddy View Post
                            Dave,

                            At one time I too "thought" that the knurled knob was for fine adjustment.

                            -SD:
                            Now I look at it again, it is also conceivable that it pushes and pulls against the brake which is not connected solidly to the slider?

                            Dave

                            Comment


                            • #15
                              Getting a feeler gauge between the top jaws is kind of meaningless. They are meant to read the inside diameter of a hole, a groove, etc. It's the outside edges of those jaws that matters, and it's the distance between those edges that you are adjusting the 0-25 scale for, so it reads correctly. That's why you need a known diameter hole to set the caliper to- otherwise you have no reference. For the lower jaws, your reference is normally the closed jaws- in other words a size of zero. It would be wise to also check a known diameter rod to see if the indication shows it correctly.

                              It appears that the knurled knob is there to lock the movable jaw when you have a position that you want to hold. The lever to the left of it, with the bit of knurling on it, is what you push on with your thumb when you want to move the movable jaw. You'll find that if the jaw is locked, there will be no movement of the lever. When it is not locked, you'll be able to feel some movement in the lever.
                              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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