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Chuck centering device for ROTAB

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  • #16
    Center the chuck via it's OD and then carefully scribe it's circumference on your RT. Next time you plop it down you can easily center it within the scribed circle and be very close to being actually centered.
    Location: Saskatoon, Saskatchewan, Canada

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    • #17
      Originally posted by Arcane View Post
      Center the chuck via it's OD and then carefully scribe it's circumference on your RT. Next time you plop it down you can easily center it within the scribed circle and be very close to being actually centered.
      S**t, you think I can see that well?
      Len

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      • #18
        Originally posted by Doozer View Post
        Not trying to be a dlck, but
        --Doozer
        You've proven it to be a natural talent so I say run with it!

        Just remember there's those out here who don't GAF.
        Len

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        • #19
          I also have a 10" RT and a four jaw chuck that I use on it. The work is adjusted to be centered using the chuck's jaws, so the chuck itself does not need to be centered to a high degree of accuracy. I just use an ordinary adjustable square. I have the approximate dimension to set the square to saved with the chuck. Set the square to that number and push the chuck with it from all four sides to get it fairly well centered. If I need or want it better than 1/32" I just adjust the square a bit from that basic setting. But for most work using the chuck on the RT, 1/32" is good enough.

          Then the precise centering is done with the chuck's jaws.

          The bigger problem is getting the RT centered under the mill's vertical axis so the X-Y dials or DROs can be set to zero. For that I use a MT adapter in the center hole of the RT. The same MT fits both my RT and my lathe, so I used the lathe to drill, bore, and ream a precise, 0.400" hole in that MT adapter. And I turned the OD to an exact diameter to match the center hole in some parts I was working on". So I can use an edge finder on the ID of that projection of the MT adapter to find the precise center. Once the dials are zeroed, I can just drop those parts on the adapter and they are centered on the table. For work with the chuck, the MT adapter is removed with a small tool that I made (long bolt with a sliding weight = a reverse hammer) and the 4 jaw chuck or other work holding means are used to mount the work.

          I will see if I can find some photos.



          Originally posted by QSIMDO View Post
          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.
          Last edited by Paul Alciatore; 11-29-2019, 05:04 PM.
          Paul A.
          SE Texas

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

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          • #20
            I truly appreciate any personal experience and solutions offered!
            Len

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            • #21
              I have an 8" Phase II rotary table and a Phase II 6" 3 jaw chuck/mount plate for the table. In addition I obtained an alignment plug with the chuck/mount plate from Phase II that sits in the center recess of the table, above the MT. Not sure if the 10" table utilizes the same plug arrangement but perhaps this might be a methodology you may consider for your application?

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              • #22
                I have a 6" rotary table which has four slots, which make it easy to attach a four jaw independent. I just make it concentric with the table by feel before tightening it down. I have drilled and tapped for direct mounting of a 5" three jaw scroll. It needs careful planning to get three holes in the top of a table with four slots, but it can be done. The top has a MT2 in the centre, and I put a short test bar in the socket, not too tight, and close the three jaws lightly on the bar before tightening the mounting bolts. This works to about 0.001" tir which is good enough for most work. If the axis of the table needs to be in line with the spindle, I line up the centre drilling in the test bar optically before clamping down the RT.

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                • #23
                  If you need the chuck on the RT, why take it off in between times? Why not just get it centered once and leave it on?

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                  • #24
                    Is the rotary table setup for first or second operations?

                    This makes a considerable difference.

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                    • #25
                      Different jobs need different work holding. AND, have you ever tried to pickup a 10" RT? I dropped mine once due to the weight and my greasy hands. And that was with nothing attached to it. With my 6", four jaw chuck, it would be almost impossible for me to lift it. So, even if I always used the four jaw on the RT, I do not always have the RT mounted on my mill's table. I do not have a hoist in my shop so I have to remove it without the chuck.

                      I promised some photos in my post above. Here are some that I already had showing my centering device. I use this both for centering the RT under the quill and for locating parts on the table with a center hole that matches the OD of the adapter's protrusion. The bottom of that hole is drilled and tapped 1/4-20 for the removal tool to grab it.







                      If I can find the time, I will try to take a photo of my chuck centering with the adjustable square.





                      Originally posted by Toolguy View Post
                      If you need the chuck on the RT, why take it off in between times? Why not just get it centered once and leave it on?
                      Last edited by Paul Alciatore; 11-29-2019, 05:05 PM.
                      Paul A.
                      SE Texas

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

                      Comment


                      • #26
                        I made a D1 adapter, actually two, one for the RT one for the dividing head. Registers on each then you drop whatever on it and it mounts like you're putting it on the lathe. Seemed like a good idea, you could stake stuff off the lathe and plunk on the RT/DH....truth is, can't remember the last time i used it....but its there if I need it
                        .

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                        • #27
                          Originally posted by Paul Alciatore View Post
                          Different jobs need different work holding. AND, have you ever tried to pickup a 10" RT? I dropped mine once due to the weight and my greasy hands. And that was with nothing attached to it. With my 6", four jaw chuck, it would be almost impossible for me to lift it. So, even if I always used the four jaw on the RT, I do not always have the RT mounted on my mill's table. I do not have a hoist in my shop so I have to remove it without the chuck.

                          I promised some photos in my post above. Here are some that I already had showing my centering device. I use this both for centering the RT under the quill and for locating parts on the table with a center hole that matches the OD of the adapter's protrusion. The bottom of that hole is drilled and tapped 1/4-20 for the removal tool to grab it.

                          If I can find the time, I will try to take a photo of my chuck centering with the adjustable square.
                          Yes, that's along the lines of what I was thinking!
                          I think it was just 3 years ago before my new valve was the last time I lifted my 15" Bridgeport. Now I have enough trouble just pushing the cart it's on so it's posted on Craig's for some young buck to handle.

                          Len

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                          • #28
                            We're not alone either; https://www.youtube.com/watch?v=cxCWmYg3Mgc
                            Len

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                            • #29
                              Check if the MT taper on the Rotab is not removable.
                              They are often a removable sleeve with a straight OD.

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                              • #30
                                Originally posted by thaiguzzi View Post
                                Check if the MT taper on the Rotab is not removable.
                                They are often a removable sleeve with a straight OD.
                                Yes. I have found a sleeve in what I thought was a machined spigot. JR
                                My old yahoo group. Bridgeport Mill Group

                                https://groups.yahoo.com/neo/groups/...port_mill/info

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