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Chuck centering device for ROTAB

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  • Chuck centering device for ROTAB

    I have a 10" Phase II rotary table on which I mount a 8" 4 jaw chuck.
    The chuck is a D1-5 with the posts removed and has 4 through bolts to mount.
    Knowing the Phase II has a MT 3 center taper I looked up the D1-5 chuck back dimensions with a thought to making a fixture to center the chuck.
    Just thought I'd ask first if anyone knows if a device like that exists before I invest the time because the taper in the center of the chuck is shallow, wide and 7 degrees, some minutes and a few seconds.
    I can get the 7 degrees.
    Len

  • #2
    You can get a morse3 to straight shank adapter which will simplify the fixture

    Comment


    • #3
      Originally posted by bob_s View Post
      You can get a morse3 to straight shank adapter which will simplify the fixture
      The centring taper on a D1-5 is 3.25 inches OD, so it'll take the straight shank adaptor plus a hunk of steel...

      Dimensions here: https://www.smalltools.com/lathe-spi...ication-chart/

      Dave H. (the other one)
      Rules are for the obedience of fools, and the guidance of wise men.

      Holbrook Model C Number 13 lathe, Testa 2U universal mill, bikes and tools

      Comment


      • #4
        Why do you need a "device" to centre the rotab??? Just run an indicator around the inside of the centre hole and adjust X-Y as you go.

        If you are trying to do it with the chuck still in place you would place the part in the chuck and centre it. As long as the part you are working on or some point on the part that you want centred is indicated to the spindle and rotates accurately under the spindle your OK. A 3 jaw takes more work since the run out of the chuck varies with the jaw position.
        Last edited by loose nut; 11-27-2019, 10:28 PM.
        The shortest distance between two points is a circle of infinite diameter.

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

        Comment


        • #5
          Loose, read it again.
          I want something to quickly center the 4 jaw chuck onto the rotary table .
          It's held by 4 bolts in the T slots.
          Trying to eliminate some steps here so if I only have to indicate the chuck then the part so I can get milling sometime before midnight.
          Len

          Comment


          • #6
            Does it not work just as he said, since it is a 4 jaw? Just get it pretty close by eye, then put the part in it and center part as normal?

            The 4 jaw should let you center the part without the chuck itself having to be perfectly centered

            1601

            Keep eye on ball.
            Hashim Khan

            Comment


            • #7
              I have to bolt the chuck on every time I want to use the rotary table so, I center the rotab, mount and center the chuck, insert the part then center the part.
              Sometimes I want the part off center for eccentric milling.
              Just trying to reduce steps and eliminate opportunities for error compounding.
              If I can set the chuck on and be centered with the table it will make me much happier and be more pleasant to be around thereby not pissing my wife off, capisce?
              Len

              Comment


              • #8
                For my little 3 inch rotab with a 2 inch chuck, I made a spring loaded "center" that fit in the rotab central hole and made a plug with a detent in the middle for the underside of the chuck. When the point of the center found the detent in the base of the chuck it was centered or close to it.

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

                Comment


                • #9
                  OK, what I "hear" is that you just "want" it centered decently with no effort, which is a perfectly valid desire, even if it is not actually "technically needed for function"..
                  1601

                  Keep eye on ball.
                  Hashim Khan

                  Comment


                  • #10
                    Originally posted by QSIMDO View Post
                    Loose, read it again.
                    I want something to quickly center the 4 jaw chuck onto the rotary table .
                    It's held by 4 bolts in the T slots.
                    Trying to eliminate some steps here so if I only have to indicate the chuck then the part so I can get milling sometime before midnight.
                    What J tiers and I are trying to say is you don't need to centre the 4 jaw, at least not any better then "close enough" by eye. It is a 4 jaw so you will have to mount your work piece and then align that under the spindle. Other then indicating the OD of the chuck, which you could do but why, there really isn't any better way (yes you could inventor a method like you want to, again why) to do it. Measure from the edge of the rotab to the chuck and when you are close then leave it.For that matter as long as the work piece will centre under the spindle it wouldn't matter if the chuck was off centre by a couple of inches.It is the part that needs to be centred under the spindle not the 4 jaw chuck. You want to speed up the operation by eliminating or minimizing a step, do that by not worrying about centring the 4 jaw any more then necessary.

                    A 3 jaw chuck is a different matter all together.
                    Last edited by loose nut; 11-28-2019, 12:09 PM.
                    The shortest distance between two points is a circle of infinite diameter.

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

                    Comment


                    • #11
                      My grandmother says it is good to "want".

                      If you find frustration with centering a chuck on a rotary table
                      you need a different hobby. Really.

                      Centering the chuck on a rotary table should take less than 2 minutes.
                      If you can't accomplish this, you need to figure out what you do not know
                      and practice. Simple as that. Not trying to be a dlck, but indicating things
                      in the machine shop is as common as putting gas in your car. Seriously.

                      --Doozer
                      DZER

                      Comment


                      • #12
                        Originally posted by loose nut View Post

                        What J tiers and I are trying to say is you don't need to centre the 4 jaw, at least not any better then "close enough" by eye. It is a 4 jaw so you will have to mount your work piece and then align that under the spindle. Other then indicating the OD of the chuck, which you could do but why, there really isn't any better way (yes you could inventor a method like you want to, again why) to do it. Measure from the edge of the rotab to the chuck and when you are close then leave it.For that matter as long as the work piece will centre under the spindle it wouldn't matter if the chuck was off centre by a couple of inches.It is the part that needs to be centred under the spindle not the 4 jaw chuck. You want to speed up the operation by eliminating or minimizing a step, do that by not worrying about centring the 4 jaw any more then necessary.

                        A 3 jaw chuck is a different matter all together.
                        I HAD what I thought to be a truly valid reason for wanting to do this when I started out, but then you guys had to come at me with logic and proven technique and screwed me ALL up!
                        Thank you!
                        Len

                        Comment


                        • #13
                          Another quickie method.
                          measure from edge of table to chuck with tail of your Vernier caliper.. even if you have to hold it at a slight angle.
                          I will be surprised if you can't quickly get it within 20 thou..

                          IT,'s not not uncommon for folks with machine tools to strive for accuracy when it's not warranted, NOR is it uncommon to not want to get used to basic tasks like clocking a vide to a mill table or centering work in a 4 jaw. The problem with those two things, there are little tricks that make it easy, that you may not discover yourself.
                          LIke clocking a vise, if you don't snug one side and only move the other side, it will take a very long time., just like making changes to taper angle on a compound without a dial indicator mounted.

                          Comment


                          • #14
                            Originally posted by QSIMDO View Post

                            I HAD what I thought to be a truly valid reason for wanting to do this when I started out, but then you guys had to come at me with logic and proven technique and screwed me ALL up!
                            Thank you!
                            Always willing to screw up someones life, so glad to help.
                            The shortest distance between two points is a circle of infinite diameter.

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

                            Comment


                            • #15
                              Originally posted by QSIMDO View Post

                              I HAD what I thought to be a truly valid reason for wanting to do this when I started out, but then you guys had to come at me with logic and proven technique and screwed me ALL up!
                              Thank you!
                              If you really really want something quick to get you close to centered, turn a disc of some scrap material the same diameter as the rotab, and bore it out to a slip fit clearance to the chuck's o.d.

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