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  • Cylinder square now with more lathe

    Got the mini-lathe going again thanks to some spare parts from Danlb. Turned a relief .060 on the bottom of the cylinder square that I was making out of a large piston pin. Job absolutely requires carbide -- I dunno what they made it out of, but the case is about .250 deep and resists everything except fresh and sharp carbide. I chucked it by the ID and used a poor man's bullnose center on the tailstock -- by slipping a large washer over the point of the regular live center. It took up the entire usable length of the bed. Used a 5/16 solid carbide, miniature boring bar at low RPM. Work piece is 2.5" dia x 6" long. .375 wall thick.
    Pile of blue chips. Beautiful finish.

    When I left off lapping it, I had less than 001 to go, and it was going easy -- using a diamond whetstone soaked in oil on a glass plate. It only takes a few swipes to make the indicator needle move the right way. Its much easier with this thin lip instead of trying to do the whole thing. Thanks to whoever suggested that in the old thread, sorry I forgot who

    Will post more later when I start getting some "interesting" measurements. But for now, I have to clean up my work area and get set up with the granite again. My "real" shop is unheated and I refuse to leave my tools out there and freeze myself, so I'm doing all this on top of the washer and dryer.

    Just felt like doing the impossible, so I figured I better have pics.


    Click image for larger version  Name:	chips2.JPG Views:	0 Size:	215.4 KB ID:	1857008Click image for larger version  Name:	chips1.JPG Views:	0 Size:	146.7 KB ID:	1857009
    Last edited by nickel-city-fab; 02-22-2020, 05:59 PM.

  • #2
    Congrats! You have now proven an old adage ... You used the lathe to build itself. I always heard that but you put it t the test.

    You also disproved a popular misconception ... You've shown that the lowly 7x10 really can cut medium sized bars of hardened steel using carbide.

    Soon you will have that cylindrical square perfectly square and can use that to start building a mill.

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

    Location: SF East Bay.

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    • #3
      Heh, it was just desperation. I originally wanted the cylinder square to test a level I want to build -- an Egyptian level. I do plan on a somewhat larger lathe in the future if the taxes are kind to me. I can see how the lathe could build itself though.

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      • #4
        An Egyptian level---Sounds like a pyramid scheme to me--
        Brian Rupnow

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        • #5
          Originally posted by brian Rupnow View Post
          An Egyptian level---Sounds like a pyramid scheme to me--
          *groan* fnar fnar fnar....

          Been enjoying your engine series. I'm fascinated by some of the early ones, have you ever seen the older Kohler 4-cylinders?

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          • #6
            Curious, how are you verifying that it is square?

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            • #7
              Originally posted by RB211 View Post
              Curious, how are you verifying that it is square?
              Have been using indicators on the surface plate (in the previous thread that was closed). I didn't do any turning on the area that I had already lapped, don't want to make extra work for myself. Will try and post pics of the checking setup tomorrow. Started with a regular indicator and worked down to the tenths indicator as I got closer. Also honing stones with plenty of oil.

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              • #8
                Originally posted by nickel-city-fab View Post

                Have been using indicators on the surface plate (in the previous thread that was closed). I didn't do any turning on the area that I had already lapped, don't want to make extra work for myself. Will try and post pics of the checking setup tomorrow. Started with a regular indicator and worked down to the tenths indicator as I got closer. Also honing stones with plenty of oil.
                Cool

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                • #9
                  Originally posted by nickel-city-fab View Post
                  Heh, it was just desperation. I originally wanted the cylinder square to test a level I want to build -- an Egyptian level. I do plan on a somewhat larger lathe in the future if the taxes are kind to me. I can see how the lathe could build itself though.
                  What pray tell is an Egyptian level? Google was of no help.
                  Location: Saskatoon, Saskatchewan, Canada

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                  • #10
                    Originally posted by Arcane View Post

                    What pray tell is an Egyptian level? Google was of no help.
                    The Egyptians used a combination of square and level, which looked like a regular square with a plumb bob hanging from the corner. There was a cross bar connecting both legs of the square, and when the bob hung over the exact middle of this bar, it was level. Here's a link: https://mae.ufl.edu/~uhk/EGYPTIAN-LEVEL.pdf
                    The crazy thing about it is the kind of accuracy they were able to get 4,000 years ago. The stones of the Great Pyramid are fitted together in the same way that we rub surface plates -- a .003 feeler won't go. The north corner was knocked 5/8" out of alignment with the North star by an earthquake around 950AD. And here we are trying to get a 16th or something with hardware store tools. I mean, the stuff they did back then was just insane even by modern standards.
                    Last edited by nickel-city-fab; 02-22-2020, 10:54 PM.

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                    • #11
                      Originally posted by nickel-city-fab View Post

                      The Egyptians used a combination of square and level, which looked like a regular square with a plumb bob hanging from the corner. There was a cross bar connecting both legs of the square, and when the bob hung over the exact middle of this bar, it was level. Here's a link: https://mae.ufl.edu/~uhk/EGYPTIAN-LEVEL.pdf
                      The crazy thing about it is the kind of accuracy they were able to get 4,000 years ago. The stones of the Great Pyramid are fitted together in the same way that we rub surface plates -- a .003 feeler won't go. The north corner was knocked 5/8" out of alignment with the North star by an earthquake around 950AD. And here we are trying to get a 16th or something with hardware store tools. I mean, the stuff they did back then was just insane even by modern standards.
                      I think they had help

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                      • #12
                        N C F is kindly sending me one of those pins and when I true up one of the ends, I intend to test it by putting the base against a couple of heavy plates at right angles to one another like a thin vee block. I happen to have two plates of Densimet tungsten which wont move easily when on the surface table. Assuming the od of the pin is cylindrical, not oval or lobed, then turning it while resting against the plates with a dti resting at the top of the pin will prove its squareness. I will be happy with 0.0001" wobble for my needs are far less demanding than that.
                        I don't think I would dare to try that on my 7 X 12 lathe, the Smart & Brown at the museum is much more suitable.
                        Last edited by old mart; 02-23-2020, 10:19 AM.

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                        • #13
                          Originally posted by RB211 View Post

                          I think they had help
                          Its entirely possible, there's been books written about it. But frankly, I don't think we give the ancients nearly enough credit. For example, it is known that the Greeks had automatons. Pythagoras, who is famous for his 3-4-5 triangle, got that from the Egyptians (he went to school in Egypt)

                          It makes me wonder what would a Babylonian computer look like since their system was sexagesimal (base 60)

                          Nah, its way too early for that and i'm all fuzzy-headed today.

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                          • #14
                            There is one thing you did when turning the pin which I can find fault with unfortunately. You have relieved the outside of the wall instead of the inside. The pin is now sitting on a smaller diameter than it could, lowering the potential accuracy.

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                            • #15
                              Originally posted by old mart View Post
                              There is one thing you did when turning the pin which I can find fault with unfortunately. You have relieved the outside of the wall instead of the inside. The pin is now sitting on a smaller diameter than it could, lowering the potential accuracy.
                              True, and it simply didn't occur to me. On the other hand, there wasn't any other way to do the job. I had to grip it by the inside diameter and use a bull nosed center in the tail stock. The good thing about it though is that now the base is narrow enough to fit on my bench stone when I hone it. Previously, the pin was too wide and the OD hung over the sides of the stone.

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