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How do you measure the INSIDE of a bottle?

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  • How do you measure the INSIDE of a bottle?

    I have some parts to examine. Think of a beer bottle. The dimensions are different, but the idea is the same. They are tubes about 8" long, 1" ID and 1.25" OD. One end is closed. They have been deformed and the wall may be uneven in thickness. The deformation may be as much as .25", and will be towards the closed end. The mouth will always be the narrow part. I want to find out where it deformed and how much the deformation is, and so I will be taking multiple measurements at different distances from the bottom.

    Normally I would use telescoping gages to measure the ID. However I see a possible problem in getting a gage that is extended to 1.25" out of a 1.00" ID mouth. I could derive the ID from and OD and two wall thicknesses... but I don't know how to measure the wall thickness of a bottle.

    It has to be a non-destructive test.

    I suspect there might be a tool like a telescoping gage with a read out. If so, please tell me where I can find one, but unless they are less than $100 please give me some ideas with "the usual tools". I can't spend a few hundred bucks on this project.


    Thanks
    Dan

  • #2
    Easy pour water into it then measure the volume of the water it takes to fill it, and convert that to area mass, if I remember cubic centilitres to centimetres. Alistair
    Please excuse my typing as I have a form of parkinsons disease

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    • #3
      If the difference between maximum and minimum diameters is in the range of 1/4" you might get away with a dial
      bore gauge. I'm curious now; will have to check mine for travel when I get to the shop...
      Keith
      __________________________
      Just one project too many--that's what finally got him...

      Comment


      • #4
        Double ended calipers, such as woodturners use.

        Or, if you need greater accuracy, transfer calipers. Starrett's #37 calipers are an example.

        Comment


        • #5
          John beat me to it so I'm deleting my similar suggestion.
          Last edited by Arcane; 03-21-2018, 01:08 PM.
          Location: Saskatoon, Saskatchewan, Canada

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          • #6
            Something like this might work: https://www.ebay.com/itm/Pair-8-Outs...ty!78052!US!-1

            I have no association with the seller, maker or the venue. It is offered as an idea.

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            • #7
              Ultrasonic thickness measurement and OD measurement with weapon of choice.
              Ultrasonic measurement has some limitations but based on input data this is best I can guess

              Or digital ID caliper like these:
              https://www.greatgages.com/collectio...igital-caliper

              you might need to hack longer "prongs" for the caliper to reach 8" hole bottom (and multiply the readings with factor X after that)
              Location: Helsinki, Finland, Europe

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              • #8
                Something long and forked.. the forks to suit your space requirements.. inside has a anvil that runs on inner surface, outside has plunger indicator.

                I made something similar to measure butting/thickness transitions in bicycle tubing. In that case I used a brass tipped set screw for the anvil. The more rigid the forks, the better.

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                • #9
                  You could try inside dial callipers, the sprung type. They can be checked each time they are used against a known length such as the jaws of a standard Vernier or digital calliper.
                  Look in the Mitutoyo catalogue for "internal calliper gauges" for illustrations of the instruments that I am recommending. There are several makers, not all as expensive as Mitutoyo.
                  MattiJ beat me to post.
                  Last edited by old mart; 03-21-2018, 02:22 PM.

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                  • #10
                    Cheap quick test ?
                    tool under one dollar ?

                    get a balloon from a party store -not a large one !

                    Slip the balloon neck onto a piece of tubing -tightly

                    Stick the balloon into the bottle and inflate. You will see when the rubber touches the sides of the bottle and then stop and pinch off the tube and pull it out of the bottle and measure the diameter

                    Rich

                    OK, Maybe this is not a glass bottle, then read the following post !
                    Last edited by Rich Carlstedt; 03-21-2018, 02:38 PM.
                    Green Bay, WI

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                    • #11
                      Ok, I was thinking of the title when I used a bottle in the above post ...maybe this is metal and not visible ..if so here is another easy method but may be $
                      Do you have a Blake Center finder or a dial test Indicator with a large range ?

                      if so, then you should be able to test the "bottle in a lathe or mill.
                      Chuck the bottle in a 3 jaw and mount the Blake in the tailstock.
                      Using a long bent probe (5-6") introduce the probe through the neck and into the bottle.
                      Now rotate the bottle and record the readings and the lateral location.
                      Remove the part and check the calibration readings of the Blake to see what the ID's are.

                      Rich
                      Green Bay, WI

                      Comment


                      • #12
                        Originally posted by Rich Carlstedt View Post
                        Cheap quick test ?
                        tool under one dollar ?

                        get a balloon from a party store -not a large one !

                        Slip the balloon neck onto a piece of tubing -tightly

                        Stick the balloon into the bottle and inflate. You will see when the rubber touches the sides of the bottle and then stop and pinch off the tube and pull it out of the bottle and measure the diameter

                        Rich

                        OK, Maybe this is not a glass bottle, then read the following post !
                        freeze water in tube remove and measure
                        san jose, ca. usa

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                        • #13
                          Lots of options so far for measuring a variety of things. Are you after ID, volume or wall thickness? You didn't state that in the first post. And so far I've seen options for all three in the replies.

                          For ID I'm thinking that a set of the old sprung arm style inside calipers with the little adjustment screws could be modified with some heating to alter the shape of the arms so you can get in through the end opening and feel the size at some location. Then without turning the adjustment screw compress the arms back and withdraw the caliper and then measure the spread with dial or digital calipers or micrometer. With only a little care and practice you can get to within 3 to 5 thou easily. And closer to a couple of thou with a little practice at getting the feel just right. Very old school method that worked for most of the industrial revolution until someone gave us internal mics and spring loaded bore gauges.

                          For wall thickness it would not take a lot of effort to make up a long "U" shape with a dial gauge on one arm and the other bent inwards to form a dogleg to get around the neck and let you measure the wall thickness directly. Sort of like a sheet metal or fabric dial based thickness gauge on steroids.
                          Chilliwack BC, Canada

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                          • #14
                            There is a tool out there called a Magna-Mic. Uses a small ball bearing and a magnetic coil. Calibrated to measure thickness or the gap between the ball and the coil on non-magnetic stuff. Glass, plastics etc. Got one at work. We use it to measure the wall thickness of plastic bottles we mold.

                            There are also Ultrasonic versions, but I have no experience with them.

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                            • #15
                              Yes Greg, could also be a home brew magnetic method:
                              Make 2 ferrite cored cylindrical coils of diameter about the wall thickness. The outer coil will be the field coil.
                              The outer coil will be a long solenoid ( length > 3 times diameter.)
                              The inner sense coil can be shorter and can have a bullet nose for better positional accuracy.
                              Excite the outer field coil, and feed the inner sense coil to o'scope.
                              Firstly calibrate for axial distance as a function of sense voltage.
                              Then insert the sense coil in the bottle, find the peak voltage and infer the wall thicknesses.

                              The sense voltage varies by the square of the wall thickness so the measurement should be sensitive.
                              ( Accuracy will depend on some mechanical details)

                              I have not done this, but I spoke to a Canadian person one time who was doing it, to measure distance , and also metal conductivity.

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