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on the subject of lathe leveling - a funny story

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  • on the subject of lathe leveling - a funny story

    This was posted to my local metalworking club today and I had to repost it:

    Funny story about lathe leveling... my apprenticeship was as a maintenance machinist at a naval shipyard here locally and part of that job was installing (and moving) machinery. We got tasked with moving a couple old turret lathes from the north end of the machine shop to the south end. Got them moved and bolted down, and started the leveling process. One thing you need to do during that process once you get close to level is make a change and let the machine sit for several hours so they'll settle. This meant we'd make a change first thing in the morning, then check it in the afternoon and retweak. We went through several days of this and we'd get it dead on in the AM, by afternoon it would move a bit and we'd readjust. Normally you get it dialed in after a couple rounds. These things wouldn't take a set for anything. Then I had an idea... we set it in the morning, checked it in the afternoon (it was off), then rechecked it the next morning (dead on).

    South end of the building (built in 1936) is built on fill right next to the water... lathes were changing level as the tide went in and out and the floor swelled and receded. Machine shop wouldn't hear of putting them somewhere else so we told them "well they're accurate once a day, you get to guess when".

    In response, another member wrote:

    I talked to a guy from one of Boeing's plants on the Duwamish flats who said the same thing ... they consulted the tide tables before doing accurate work.

    metalmagpie

  • #2
    Originally posted by metalmagpie View Post
    This was posted to my local metalworking club today and I had to repost it:

    Funny story about lathe leveling... my apprenticeship was as a maintenance machinist at a naval shipyard here locally and part of that job was installing (and moving) machinery. We got tasked with moving a couple old turret lathes from the north end of the machine shop to the south end. Got them moved and bolted down, and started the leveling process. One thing you need to do during that process once you get close to level is make a change and let the machine sit for several hours so they'll settle. This meant we'd make a change first thing in the morning, then check it in the afternoon and retweak. We went through several days of this and we'd get it dead on in the AM, by afternoon it would move a bit and we'd readjust. Normally you get it dialed in after a couple rounds. These things wouldn't take a set for anything. Then I had an idea... we set it in the morning, checked it in the afternoon (it was off), then rechecked it the next morning (dead on).

    South end of the building (built in 1936) is built on fill right next to the water... lathes were changing level as the tide went in and out and the floor swelled and receded. Machine shop wouldn't hear of putting them somewhere else so we told them "well they're accurate once a day, you get to guess when".

    In response, another member wrote:

    I talked to a guy from one of Boeing's plants on the Duwamish flats who said the same thing ... they consulted the tide tables before doing accurate work.

    metalmagpie
    It makes perfect sense now that at my company, the giant CNC grinder that grinds gas turbine housings sits on its own 10 ft deep block of concrete.

    Sent from my SM-G950U1 using Tapatalk

    Comment


    • #3
      Originally posted by metalmagpie View Post
      ... Then I had an idea... we set it in the morning, checked it in the afternoon (it was off), then rechecked it the next morning (dead on).

      South end of the building (built in 1936) is built on fill right next to the water... lathes were changing level as the tide went in and out and the floor swelled and receded. ...
      Good one. Did not see that coming. I was expecting a window that let sunshine in in the afternoon.
      Location: Long Island, N.Y.

      Comment


      • #4
        The ground around here moves between rain and drought. There is a broken section of a major road near here which is below the level of the rest of the street after dry weather but above it after rainy weather. I have wondered if there may be a sinkhole-in-the-making below it. I try to avoid driving over it.
        Paul A.
        SE Texas

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

        Comment


        • #5
          Originally posted by Paul Alciatore View Post
          The ground around here moves between rain and drought. There is a broken section of a major road near here which is below the level of the rest of the street after dry weather but above it after rainy weather. I have wondered if there may be a sinkhole-in-the-making below it. I try to avoid driving over it.
          Sounds like bentonite soil. Got a lot of it around here. We

          Comment


          • #6
            Why are people obsessed with machines being level?
            The only reason that I can come up with
            is so they have a reason to complain about it
            when they are not.
            Level is functionally irrelevant.

            -Doozer
            DZER

            Comment


            • #7
              Level is absolutely irrelevant like Doozer said. Unfortunately leveling is the only reasonably convenient method of assuring the bed is not twisted.

              Think about machinery on board ships. They will never stay level yet presumably they work just fine.

              Comment


              • #8
                Most important might be equal pressure on each of the four legs. A reinforced concrete slab should keep the bed from bending when the floor moves. It's also possible that the legs might need to be adjusted unequally to get the bed straight (not necessarily level), in which case maybe four strain gauges could be placed under the legs and then compared to a calibrated value and adjusted as necessary.
                http://pauleschoen.com/pix/PM08_P76_P54.png
                Paul , P S Technology, Inc. and MrTibbs
                USA Maryland 21030

                Comment


                • #9
                  Originally posted by Doozer View Post
                  Why are people obsessed with machines being level?
                  The only reason that I can come up with
                  is so they have a reason to complain about it
                  when they are not.
                  Level is functionally irrelevant.

                  -Doozer
                  That's a very helpful thing to know for people with small shops . You can save a lot of space by bolting your lathe to the wall.

                  You've been on this forum long enough to know that "leveling a lathe" on here usually means ensuring that it's solidly bolted down to a stable base and free of twist. And sometimes actually leveling the lathe is the best way to at least get close to that condition.
                  Last edited by cameron; 06-26-2019, 06:29 PM.

                  Comment


                  • #10
                    Originally posted by Doozer View Post
                    Why are people obsessed with machines being level?
                    The only reason that I can come up with
                    is so they have a reason to complain about it
                    when they are not.
                    Level is functionally irrelevant.

                    -Doozer
                    The return of IOWOLF !
                    1601

                    Keep eye on ball.
                    Hashim Khan

                    Comment


                    • #11
                      I hate it when the coolant stays in the mill slots, because it's not level.

                      Comment


                      • #12
                        Level is functionally irrelevant.
                        "Level" is shorthand for "Correctly set up".
                        "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

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                        • #13
                          Originally posted by Doozer View Post
                          Why are people obsessed with machines being level?
                          The only reason that I can come up with
                          is so they have a reason to complain about it
                          when they are not.
                          Level is functionally irrelevant.

                          -Doozer
                          That brought a smile to my face. I have a CNC mill and as a program runs the whole machine tips from side to side. Not only is it not level but I am too lazy to even shim it to stop the tipping. It has always worked well enough for the stuff I do. A negative is it allows the machine to vibrate which I'm sure is not good for the machine or carbide end mill life.

                          Comment


                          • #14
                            Originally posted by 754 View Post
                            I hate it when the coolant stays in the mill slots, because it's not level.
                            just make it less level in the direction the coolant has to flow!

                            Reminds me of a cartoon called War Story, particularly the part where he's having a bath
                            https://www.youtube.com/watch?v=Fn1aVSTD-4g

                            Comment


                            • #15
                              Surely, the coolant will stay in the mill slots ONLY when its level.

                              The Smart & Brown model A that I use has been lifted a couple of inches on wood, to save my poor old back. Since it weighs over 1700 pounds, and 2/3 of the weight is in the thick cast iron stand, it has not needed any attention regarding levelling. Heavy trucks pass within 100 feet of where our machinery is and the floor shakes because about 2000 years ago, the whole area would have been tidal salt marsh.

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