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  • Fowler 8" digital caliper.

    I got this and checked it out and it is out just at the beginning of travel. Had to slam them shut to get consistent readings. Do you think I could just stone off the 1/2 thou and this would be good enough for a caliper?

    Steve

    My youtube:
    http://www.youtube.com/MyShopNotes

  • #2
    Is there a "zero" button like most calipers? If not, I would return them.

    You can apply enough pressure to make any caliper flex by a few thousandths, but the point is that you if you have to do that, then you will never get an accurate reading.

    If you want a decent set of cheap calipers, try the igaging absolute zero set. I have one (along with a mitutoyo digimatic), and would buy them again.

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    Comment


    • #3
      I did zero set them. The problem is when they open at the begionning they are gaining 1/2 a thou to 1thou. I am wondering if I could stone off that 1/2 a thou and make these work ok for calipers.
      Last edited by schor; 01-28-2018, 07:09 PM.
      Steve

      My youtube:
      http://www.youtube.com/MyShopNotes

      Comment


      • #4
        Originally posted by schor View Post
        I did zero set them. The problem is when they open at the begionning they are gaining 1/2 a thou to 1thou. I am wondering if I could stone off that 1/2 a thou and make these work ok for calipers.
        The normal procedure is to clean the jaws, close them, zero them and then use them.

        If the gib strip is too loose the sensor will rock on the scale, causing an inaccuracy.

        Edit:
        I just listened to the video. I hate video for this purpose; It took 10 minutes to explain something that could have been expressed in one paragraph.

        Your expectations are a bit high. Think of a caliper as a tool for comparing and you will be happier. Look at the specs for the tool and you might find that it's doing what it's supposed to do.

        I could not find that model on Fowler's web site. This one looked similar, and was one of their mid priced 8 inch calipers; Fowler 8"/200mm Ultra-Cal V Electronic Caliper with Lifetime Warranty 54-100-068-1 item# 541000681
        Range: 8″/200mm
        Accuracy: 0.0012″/30┬Ám
        Resolution: 0.0005″/.01mm
        Maximum Error: 0.001″/.02mm
        Repeatability: 0.0005″/.01mm
        Protection Rating IEC 60529: IP67

        Dan
        Last edited by danlb; 01-28-2018, 08:03 PM.
        At the end of the project, there is a profound difference between spare parts and extra parts.

        Comment


        • #5
          Most of those only "resolve" to a half thou, which is the smallest increment.

          Virtually ALL digital devices are stated to be accurate only to + or - one of the smallest increment, and in some cases possibly 2 of the smallest increment.

          A digital "guessing stick" (caliper) is probably doing what it should, and more, if it is accurate to a couple thou. There are so many ways for a caliper to be incorrect, starting with the leverage of the jaws against the sliding surface.

          You want a half thou, you need a micrometer with a "tenths" vernier.
          1601

          Keep eye on ball.
          Hashim Khan

          Comment


          • #6
            1. Their stated accuracy is 0.001". They do not say it, but all digital devices also ADD a +/- ONE COUNT, which is 0.0005" in this case so the overall, manufacturer's accuracy is stated as +/- 0.0015" and you can not expect any better. You can hope for it, but not expect it. If you check the figures for a Starrett caliper you will find something similar. I doubt that many calipers will state any better accuracy.

            http://www.fowlerprecision.com/Produ...100-068-1.html

            His caliper meets their specs perfectly.

            2. His technique can be described as gorilla at best and King Kong at the more likely point of the spectrum where he is operating. I can observe errors in my micrometers just from an oil film on the anvils. Calipers have more numerous sources of operational error and he does not show any actions that he is taking to eliminate any of them. This is a critique of a precision instrument and extra precautions should be taken when doing this. I would never slam any measuring instrument shut like he is doing. I would carefully clean both the caliper faces and the gauge blocks before each measurement. Did he check the adjustment of the gib screws? Were the gauge blocks cocked in the jaws? I did not see much of an effort to insure that the jaws were sitting completely flat on them. I would also zero the caliper before each measurement and recheck it after. If the two zeros are not correct then the measurement should be disregarded.

            He also uses the thumb wheel to close the caliper for each measurement. That wheel is right next to the main bar of the caliper and at one end of the depth of the jaws. It is almost certain to make the moveable jaw cock. I like to apply pressure on the two jaws at about the point where the center of contact with the object being measured is located. And gently squeeze it closed, don't slam it.

            This video proves NOTHING. NOTHING except that his technique is very, very poor. If he measured things like that in any shop that I ran, he would be looking for a job. And be missing the cost of a caliper from his paycheck.
            Last edited by Paul Alciatore; 01-28-2018, 11:10 PM.
            Paul A.

            Make it fit.
            You can't win and there is a penalty for trying!

            Comment


            • #7
              I did not watch the entire video, but skipped through as I usually do. It could well be edited down to a couple of minutes and presented as a perfect example of how not to use precision measuring instruments.

              In addition to previous mentioned how not to use a slide caliper, it also covers mis-use of micrometers and gage blocks. The mics are not zeroed prior to being used for critical measurement, nor was any attempt made at cleaning the anvils. (Same lack of zeroing and cleaning as employed with the caliper.) The mic is cranked closed on the gage block ala C-clamp and then the spindle diddled with to arrive at the desired reading.

              There is a cup of what appears to be popcorn on the bench, it may or may not be salted. A handful is taken and eaten, then the uncleaned gage block is held in the palm of the same hand for a rather significant time, heating up and getting well salted prior to use.
              Jim H.

              Comment


              • #8
                Fowler sells a lot of import $#!+ these days. Return it and get something decent.
                The shortest distance between two points is a circle of infinite diameter.

                Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                Comment


                • #9
                  Thanks for the replies. I do understand that calipers are not intended for highly accurate work.

                  I had to slam them just to get some consistency, if I didn't they would read all over the place. I'm not going to be using them for any precision work, they are my beside the computer measuring instrument when I don't want to use a tape measure or a scale.

                  The popcorn was there for a joke, the anvils were cleaned, just didn't video it.
                  Steve

                  My youtube:
                  http://www.youtube.com/MyShopNotes

                  Comment


                  • #10
                    Originally posted by schor View Post
                    Thanks for the replies. I do understand that calipers are not intended for highly accurate work.

                    I had to slam them just to get some consistency, if I didn't they would read all over the place. I'm not going to be using them for any precision work, they are my beside the computer measuring instrument when I don't want to use a tape measure or a scale.

                    The popcorn was there for a joke, the anvils were cleaned, just didn't video it.
                    Just a thought... If you slam them shut you are causing a rebound. The idea is that you should close the jaws the same way that you would measure a part, then zero it, then measure the part using the same pressure.

                    When I first got a dial caliper I practiced closing it till I could get a consistent reading every time. Maybe that would work with this caliper too?

                    Dan
                    At the end of the project, there is a profound difference between spare parts and extra parts.

                    Comment


                    • #11
                      Originally posted by danlb View Post
                      Just a thought... If you slam them shut you are causing a rebound. The idea is that you should close the jaws the same way that you would measure a part, then zero it, then measure the part using the same pressure.

                      When I first got a dial caliper I practiced closing it till I could get a consistent reading every time. Maybe that would work with this caliper too?

                      Dan
                      Thanks Dan. I have been working on trying to get consistent with this caliper and I am getting there. But now the thing is reading 1 thou over. I never had these issues with vernier or dial calipers but the ones I have are mitutoyo.
                      Steve

                      My youtube:
                      http://www.youtube.com/MyShopNotes

                      Comment


                      • #12
                        Just do not use the roller.

                        Close the jaws with your other hand. That allows control of force, and avoids the leverage issues.

                        If you have to slam them to get consistent readings, then they need cleaned, they are just defective, or they are a basic POS.

                        Also: develop the habit of cleaning the surfaces before measurements, and checking zero. If zero is off, there may be crud on the jaws, dust, dirt, tiny swarf, maybe just oil or grease. If a measurement has to be right, check the tool before and after the measurement to assure there is no difference, using a standard or a gage block that is close to the actual expected size.

                        That applies equally well to "guessing sticks" and to micrometers, although operator technique may have more details that can be done wrong when using the caliper vs a mic.
                        Last edited by J Tiers; 01-29-2018, 03:22 PM.
                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #13
                          Originally posted by schor View Post
                          I do understand that calipers are not intended for highly accurate work.
                          .
                          Actually not quite right.

                          Good quality Digital calipers, like the Mitutyo Digimatic, are just as accurate as mics IF used properly. Frequently they are used improperly when measuring and that leads to false beliefs that calipers are not as accurate. Starret and B&S are also good, probably. Cheap Imports, not so much. Accuracy costs money.
                          Last edited by loose nut; 01-30-2018, 11:18 AM.
                          The shortest distance between two points is a circle of infinite diameter.

                          Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                          Comment


                          • #14
                            I agree with loose nut, my Mitutoyo Digimatic's, 6" and 12" can be relied upon to manage consistent results. Even the inside measurement is good to 0.001".
                            I always wipe both jaws with a finger tip each time and hold up in front of a light source to verify that the jaws are fully closed. The 6" one has 0.0001" wear at the thin part of the jaw tips, which hardly matters.
                            I also have two parallax free mechanical Mitutoyo's which are very good, they seem to be missing from the current catalogue.

                            Comment


                            • #15
                              There are very few calipers which are intended to read to a "tenth". The basic design of a caliper works against it being very accurate, so a couple thou is about what you get. Only for comparison purposes do you do better than that with the usual caliper.
                              1601

                              Keep eye on ball.
                              Hashim Khan

                              Comment

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