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  • Cylindrical square questions

    I picked up an auction lot that included three cylindrical squares. I have some questions about two of them. The first two photos below show the ends of one of the squares. One end is relieved, and the other has some "0" marks engraved into it. The third photo shows a close-up of the engraving. There is a "Reference Only" sticker on the side which is not shown. If the Reference Only sticker is up the right way, then the engraved side is in contact with the surface plate.
    1. Is the Reference Only sticker upside down? I would have thought that the relieved end is the one that should be on the plate. Maybe it was done this way because they stored it upside down? The other squares appear to have the Reference Only sticker in the correct orientation. They all came from one location.
    2. Is the area between each pair of zeros the part that is considered the most square?
    3. The last image below shows the end of one of the other squares. It has a small threaded hole, only on this end. I found an image that shows a handle screwed into a similar hole. Is that what it's for? This is the smallest/lightest square, about 6" long.
    4. I put the squares side-by-side, and some light gets through. In the best orientations, it shifts towards blue with some white peeking through. The two largest squares are about a foot high. Does this sound reasonable, or should they let no light through? The surface plate is new, but I didn't get it calibrated. It's probably of reasonable quality for a Chinese plate (not the cheapest available).










  • #2
    I expect that the end with the narrow land is the bottom end, the end that goes against the surface plate. The "0" lines are where the square is the most perpendicular relative to the plate, or was when the marks were added.

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    • #3
      I don't have answers to all the questions. There could have been some squares with characteristics for special purposes for the organization.

      I haven't seen a square with that kind of zero indication, and it looks like it was not done by the manufacturer but by someone later (for whatever purpose). The closest thing it suggests to me is some squares that are made with a slight angle on one end. Meaning of course that standing on that end they tilt. So "Squareness" as a reference won't be true all the way around, but they will be square at exactly 90 degrees transverse to that tilt. The benefit of this angled surface is that you can get a reading of angularity everywhere from zero to the max angle. The photos I've seen of them then have a line of dots marked on the side so you can rotate the cylinder, get a match to your workpiece, and then read off how much the workpiece is off of square. It doesn't sound like that's what you have.

      I also gained an interesting insight since I now have two cylindrical squares, a tall and a short one. Both are solid and seem inordinately heavy, but I found on manipulating them with an indicator stand to check squareness of a workpiece that weight has an advantage. The square is less likely to move and compromise the indicator setting. I wouldn't have thought that big chunk of steel would be subject to slight moves on the surface plate, but I was surprised and found I really preferred the taller, heavier one.

      I also have a small square with one end having that tapped hole as yours does. And it came with a small handle that can be screwed in there to lift it. I presumed that the hole was there to hold a drive pin in manufacturing so the piece could be ground on centers and the handle bit was just a free afterthought. In the photo of yours it's not clear that the centers are functional, so some might be finished on centerless grinders and the tapped hole is an added feature for a lift handle.
      .
      "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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      • #4
        Originally posted by rkepler View Post
        I expect that the end with the narrow land is the bottom end, the end that goes against the surface plate. The "0" lines are where the square is the most perpendicular relative to the plate, or was when the marks were added.

        That's a reasonable hypothesis, but how could there be four places that are the truest perpendicular, and those not being at 90 degrees to one another? Two spots might suggest that, but four?
        .
        "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

        Comment


        • #5
          Originally posted by TGTool View Post
          That's a reasonable hypothesis, but how could there be four places that are the truest perpendicular, and those not being at 90 degrees to one another? Two spots might suggest that, but four?
          I think the zero points are a "range". Within that range meets whatever tolerance they were working to. The ranges are directly opposite each other. I would therefore think that the middle of the range is the most perpendicular.

          I'm pretty sure I have seen similar markings on another square that was for sale.
          Last edited by pinstripe; 02-09-2017, 11:42 AM.

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          • #6
            Originally posted by TGTool View Post
            I also gained an interesting insight since I now have two cylindrical squares, a tall and a short one. Both are solid and seem inordinately heavy, but I found on manipulating them with an indicator stand to check squareness of a workpiece that weight has an advantage. The square is less likely to move and compromise the indicator setting. I wouldn't have thought that big chunk of steel would be subject to slight moves on the surface plate, but I was surprised and found I really preferred the taller, heavier one.
            I came to the same conclusion today. I was only after a small one, but those big ones really plant themselves on the surface plate. It's all relative of course, they had cylindrical and granite squares there that were two feet wide!

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            • #7
              Originally posted by TGTool View Post
              That's a reasonable hypothesis, but how could there be four places that are the truest perpendicular, and those not being at 90 degrees to one another? Two spots might suggest that, but four?
              Maybe those marks are to tell you which quadrants contain a perpendicular surface. A go/nogo gauge perhaps. Slide it against that angle plate
              you just manufactured. Rotate until you see no/minimum light between the two. If the contact point is between the 2 zeros, it meets spec.
              Location: Long Island, N.Y.

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              • #8
                Many shops require periodic "calibration" of all inspection and manufacturing tools /instruments.
                It is true that having 4 marks of "0" seems confusing , but there are some cylinders made to special angles .
                The 4 marks allow someone to recheck the exact former points that were measured previously

                The threaded hole is for use of a handle perhaps when the instrument is needed on the manufacturing floor, or for when a DTI is needed to also check a height of an object being checked for squareness at the same time

                Rich
                Green Bay, WI

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                • #9
                  Originally posted by pinstripe;1098706...
                  [*]Is the Reference Only sticker upside down? I would have thought that the relieved end is the one that should be on the plate. Maybe it was done this way because they stored it upside down? The other squares appear to have the Reference Only sticker in the correct orientation. They all came from one location.
                  it would be most surprising if the users had engraved on the surface that should be against the plate, and which you then cannot see.

                  Usually, the "down" surface will show evidence of a fine finish, and will generally be a rim around at the the largest diameter. Pic 1 seems to show that.

                  Originally posted by pinstripe;1098706...
                  [*]Is the area between each pair of zeros the part that is considered the most square?
                  No way to tell but to test. I would probably have expected either the line at the "0" to indicate it, or one of the spaces between two lines.

                  Originally posted by pinstripe;1098706...
                  [*]The last image below shows the end of one of the other squares. It has a small threaded hole, only on this end. I found an image that shows a handle screwed into a similar hole. Is that what it's for? This is the smallest/lightest square, about 6" long.
                  A handle or lift ring may be found on these squares, yes

                  Originally posted by pinstripe;1098706...
                  [*]I put the squares side-by-side, and some light gets through. In the best orientations, it shifts towards blue with some white peeking through. The two largest squares are about a foot high. Does this sound reasonable, or should they let no light through? The surface plate is new, but I didn't get it calibrated. It's probably of reasonable quality for a Chinese plate (not the cheapest available).
                  ....
                  ideally, no light should come through if two perfect squares are set touching when on a perfect flat surface. Nothing is perfect. Everything has a tolerance. Light can get through a space which is smaller than you need to measure unless you are doing the most precise job in a temperature controlled area.

                  The error could be in the squares, or in the plate. If there are scattered areas of light, it may be the squares. If there seems to be a tilt, it could be the plate. You can lay a square down over the same area and see if the plate vs square lets through light. (gently does it).

                  Do the marks seem to indicate any greater precision than other areas? You may be able to determine if the area between likes, or between zeros is the better areas.

                  The squares which have a tilt made into them are marked to show the angle measurement along the OD, and have two lines of perpendicular diametrically opposite
                  Last edited by J Tiers; 02-09-2017, 11:57 AM.
                  1601

                  Keep eye on ball.
                  Hashim Khan

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                  • #10
                    Originally posted by pinstripe View Post
                    I think the zero points are a "range". Within that range meets whatever tolerance they were working to. The ranges are directly opposite each other. I would therefore think that the middle of the range is the most perpendicular.

                    I'm pretty sure I have seen similar markings on another square that was for sale.
                    I have a theory about the 0 marks, that they aren't so much about perpendicularity, but rather out-of-round. I have a cylinder square that I made, and I started with some steel pipe. I gripped from the inside, using my 3 jaw chuck. I didn't want the jaws to stretch the work so I was careful how much I tightened them, and took real light cuts. Despite that, I was getting strange results on the surface plate. After a bunch of testing and head scratching I discovered that the jaws had indeed stretched the work a little bit, and the 0.002" variation I was seeing was due to the part being a rounded triangle. I have put similar marks on mine, indicating where all the bulged or high spots are. Perhaps these squares were turned in a 4 jaw chuck and had the same condition?
                    Max
                    http://joyofprecision.com/

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                    • #11
                      Originally posted by J Tiers View Post
                      Do the marks seem to indicate any greater precision than other areas? You may be able to determine if the area between likes, or between zeros is the better areas.
                      I didn't spend much time with them today, but yes the two larger ones seemed to fit better within the zero ranges. The other large one has no markings. It was a very hot day, no AC in my shop.

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                      • #12
                        Originally posted by mars-red View Post
                        Perhaps these squares were turned in a 4 jaw chuck and had the same condition?
                        They may indicate out-of-round, but not because of a four-jaw. The lines are not 90 degrees apart.

                        BTW, I was listening to you and Justin while I was cleaning them up

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                        • #13
                          First you have to stop and think about how these are made. There are a couple ways I can think of. I would imaging they are centerless ground.
                          Some may be ground on centers. Either way, then the ends would have to be ground square to the sides.
                          I've seen some where the center hole is threaded and I've seen them bolted to a slotted angle plate.

                          JL..............

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                          • #14
                            Have you actually measuresd those squares for squareness? I'm asking because it is the first thing to do with unknown cylindrical squares. As they are pretty much self-checking with an indicator, there is hardly no point in trying to vaguely guess why someone has engraved something on them or what it means. Even checking them against each others tells nothing about their squareness othen than "it might be close". You have a surface plate, I presume you have an indicator and thus you have all you need for verifying their accuracy.
                            Amount of experience is in direct proportion to the value of broken equipment.

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                            • #15
                              Thanks Jaakko. I have an indicator and stand, but I thought that I needed a stand with the curve along the bottom to check for squareness? I've got one of these. I was planning to add a curved foot to it later. Is there some other way to do it?

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