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Focus on calipers

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  • #16
    Originally posted by jr45acp

    A formally trained gunsmith taught me to open my dial calipers and wipe the jaws down with a finger, then check zero. I don't know if it makes a difference but I do it instinctively.
    yes, it does........
    CNC machines only go through the motions.

    Ideas expressed may be mine, or from anyone else in the universe.
    Not responsible for clerical errors. Or those made by lay people either.
    Number formats and units may be chosen at random depending on what day it is.
    I reserve the right to use a number system with any integer base without prior notice.
    Generalizations are understood to be "often" true, but not true in every case.


    • #17
      I have used 6" Mitutoyo Vernier calipers for the last 25 years. Daily. They are readable and accurate to 0.001". Take a reading, compare to any of my quality European/US brand name mikes, always the same within a thou. I use them more on internal measurements that are not hyper critical, than telescopic guages. Mikes for the OD.
      NE Thailand.


      • #18
        Much has been said about accuracy in calipers. I fear that a whole book could be written on this subject alone. There is much truth in all that has been said.

        A high quality caliper in the hands of a skilled professional who knows how to get the most out of them would probably put the accuracy championship in the Vernier category. On the other hand, on the shop floor, with less than optimum technique and boss with a do or die attitude may reverse this in the direction of digitals. I can think of other circumstances where a dial may be more desirable. Perhaps where a comparative measurement is needed to better than the 0.0005" least count of the digitals.

        I have and use all three types in different circumstances.

        It pays to know your tools and to use the best one for the circumstances.
        Paul A.
        SE Texas

        And if you look REAL close at an analog signal,
        You will find that it has discrete steps.


        • #19
          Originally posted by Paul Alciatore
          It pays to know your tools and to use the best one for the circumstances.
          Amen to that. BTW thaiguzzi. Mitutoyo measuring instruments are as good as and sometimes better than their US and European counterparts. I have a green enameled Mit 1-2" mic that has served me well for over 35 years.


          • #20
            Agreed. Forgot to mention i've got Mitutoyo mikes too. And my best DTI's are also Mitutoyo.
            By the way, never liked dial calipers, and am too old fashioned for digital stuff. Plus my eye sight is still half decent at 51.


            • #21
              Good calipers good for 0.1 mm. The rest of you are dreamers. Take it from a
              German Toolmaker.


              • #22
                j├╝rgen, are you sure?

                surprisingly i found this chart i once made, comparing aldi digital calipers to the expensive ones i had:

                i was measuring CEJ grade 1 gage blocks. the repeatability is the same, except that with the aldi calipers it depends where on the yaws you measure.


                • #23
                  good afternoon.

                  I am gonna jump in here because i have some Starrett calipers that don't measure right. 6" Red face. Expensive to me, but I am also a poor country boy.

                  After a *lot* of email back and forth, they [the Starrett company] agreed that I should send the calipers to them and they would test them. For some months they were telling me to find some more standards and check the calipers against them.

                  the calipers measure right on my standards [up to and including 2 inches], but they sometimes don't want to repeat right. my kid has some B&S calipers that appear to repeat better than mine. as a side note for those who have been around here a while, they were given to him by Dave Smith [Thrud] several years ago when the kid decided he wanted to be a machinist. They were a gift to him from the B&S company after the infamous 1-2-3 block incident. I miss Dave. I know a lot of people do.

                  Anyway, yesterday I was discussing this with the guy at Starrett and told him that i don't trust any calipers under about 0.003" and got out the mikes then.. He wrote back that mine should be good to 0.001".

                  I am not making any claims, or arguing with anyone, but rather passing along what i was told by the maker's mouth, as it were. i own several drawers full of Starrett tools. I have used some of them for 45 years and enjoyed them, both using them and feeling them. However, i am wondering if I will ever buy another Starrett tool.

                  Further, since I sent my Starrett's off to get 'fixed', I have been using some $25.00 chinese calipers that DO repeat. Again, i make no claims and am only repeating what I have read, heard, and seen with my own eyes.

                  I think I will keep my mikes handy.

                  ........i dremel. therefore i am..........................


                  • #24
                    FWIW, my Dad was a mechanical engineer (plant engineer) for some fairly high-quality specialty paper mfgrs, and he claimed he could measure the thickness of a sheet just as accurately with a B&S dial caliper with graduations to 1 mil as he could with a B&S mike that went to .0001"


                    • #25
                      There is a lot of technique to using calipers, much like telescoping bore gauges, and indeed micrometers if you wish to get real precise.

                      If one wants to find out how accurate a set of calipers is and/or to refine one's technique, the easiest way is with gauge blocks or some smooth, hardened object like a bearing of a known size.

                      Whenever I have done this test I've always been surprised by the repeatability and accuracy I can obtain with unbranded digital calipers. I will usually get around 3 identical readings and 2 readings +-0.01mm if I make 5 readings.

                      With bad technique you could be 0.1mm out in no time, it's worth practicing on a bearing or suchlike.