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Aligning Rotab to spindle center. techniques anyone?

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  • Aligning Rotab to spindle center. techniques anyone?

    So far when I align my Rotab to the spindle, I drop a morse taper in the rotab table receptical and place a 3/4" bar ground to a point in my R8 spindle. I then buck it in by eye and further with a magnifier until the point touch. Could someone suggest other quicky methods for this task?
    mike
    Bricolage anyone?....one of lifes fun games.

  • #2
    http://bbs.homeshopmachinist.net/showthread.php?t=37241

    Comment


    • #3
      Concwentricity

      Clamp your rotary table to the mill table.

      Loosely clamp something truly round - plate directly to the rotab table, or a solid or hollow cylinder in a 3-jaw chuck which is lightly clamped - to the rotary table.

      Disengage the worm and wheel drive in the rotab so that the rotary table spins freely.

      Put a good dial indicator on the mill table or in the mill spindle collets (preferred) and locate it on the test piece round hole/shaft on the rotary table (see para 2 - above).

      Rotate the rotab table and note the indicator dial deflection - total indicated run-out (TIR)

      Tap the cylinder until TIR is reduced to zero (same as on a lathe), clamp the plate or chuck to the rotary table, re-check TIR, if not OK - re-adjust. When TIR is OK - job done.

      The hole/cylinder is now very accurately aligned to and concentric with the rotary table axis/centre.

      Re-engage the worm and worm-wheel.

      Put the dial indicator in either a collet or a drill chuck in your mill spindle.

      Use your "X" and "Y" slides to bring the centre of the plate/hole/cylinder on the rotary table under the centre of the mill spindle.

      Lower the mill quill (or if a knee mill, raise the table) and adjust the indicator to touch the hole/shaft on the rotary table - see above.

      Turn the mill spindle by hand and note the TIR - as before. Use the mill "X" and "Y" slides to reduce the indicator TIR to zero.

      Clamp the mill "X" and "Y" slides and re-check the TIR (use the mill spindle - by hand!!). If not zero, re-set/adjust.

      When OK, the job on the rotary table is concentric with the rotary table and the job on the rotary table is also concentric with the mill spindle.

      In short, the mill spindle axis is very accurately concentric with the rotary table axis.

      This is a lot of typing and reading, but I can do it much faster than I can type.

      And so will you be able to if you follow these instructions.

      Once you've done it a couple of times it will not only become very easy, but the logic of it will be very clear as well.

      I NEVER use the morse taper in the top of the rotary table as a reference as it too has manufacturing tolerances and may not be as precisely concentric with the axis of the rotary table as you might think - or hope.

      Comment


      • #4
        Originally posted by oddball racing
        I drop a morse taper in the rotab table receptical and place a 3/4" bar ground to a point in my R8 spindle.
        You don't even need a Morse adapter, just indicate off the socket:



        Another quicky I've done is turn a center mark on a Morse Taper spud. Then you can use a pointy center finder on the center mark. Not as accurate as a DTI or Co-ax on the hole, but a lot faster.
        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

        Comment


        • #5
          I like to cheat whenever I can. My time is always limited, so I try to figure ways to set up as quickly as possible to get jobs done. I use a fixture plate on my rotary table, and I have a centered 5/8" hole in the plate.

          So, when it comes time to use the table I wrestle it onto the mill, mount a worn 5/8" end mill upside down in a 5/8 collet, and lower the end mill shank right down into the center hole. Then I crank the mill X and Y to where I want it as the rotary table slides along staying aligned to the spindle axis, and bolt the table down:



          Set the DRO axes to "0" and I'm good to go.

          Total time to align on center = a few seconds. Total hassle = nada. Precision = good enuf for me so far.

          In order to use a tapered hole for alignment, I'd just use an appropriate tapered rod in a collet.

          In case you're interested, here's the full piece on making that fixture plate:

          http://www.frets.com/HomeShopTech/Pr...tureplate.html
          Cheers,

          Frank Ford
          HomeShopTech

          Comment


          • #6
            Originally posted by Frank Ford
            In case you're interested, here's the full piece on making that fixture plate:

            http://www.frets.com/HomeShopTech/Pr...tureplate.html
            Nice cheat!

            I like those hold downs, Frank - what is a source for those?

            Comment


            • #7
              Odd Ball, thanks for the thread. I been making it harder then it has to be for my basic needs!

              I haven't tried it yet but I'm told if you take two pieces of identical rod and make them touch end to end, that you fingers can resolve a difference of .001. Anyone ever tried this? It's simpler then putting two points together and less chance of damaging the points.
              Last edited by Your Old Dog; 11-09-2009, 09:20 AM.
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              Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

              It is true, there is nothing free about freedom, don't be so quick to give it away.

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              • #8
                Originally posted by Your Old Dog
                Odd Ball, thanks for the thread. I been making it harder then it has to be for my basic needs!

                I haven't tried it yet but I'm told if you take two pieces of identical rod and make them touch end to end, that you fingers can resolve a difference of .001. Anyone ever tried this? It's simpler then putting two points together and less chance of damaging the points.
                I think it depends on how thick the calluses are on your finger tips. :-)
                ...lew...

                Comment


                • #9
                  I'm with Frank Ford on this. Quick and dirty works for me too. I turned a slug with a 1/4" hole in the center to fit in the hole of my rotab. I then put a 1/4" endmill backwards in the collet and when it drops nicely into the hole, I'm there.



                  That same slug is used to register the backplate for my 4 jaw chuck.



                  I also turned a slug that drops into the hole in the chuck the same way.

                  Ernie (VE7ERN)

                  May the wind be always at your back

                  Comment


                  • #10
                    I like those hold downs, Frank - what is a source for those?
                    If you mean the low profile ones I'm using to hold the aluminum round in the article, those are "toe clamps," and they are really cool, but kinda spendy. McMaster-Carr has them at the bottom of Page 2559 on their online catalog.
                    Cheers,

                    Frank Ford
                    HomeShopTech

                    Comment


                    • #11
                      I turned an MT-2 that fits the center hole on the rotab and has a 1/8 dowel pin in the center. I then made a small piece with a hole that should make a running fit with the dowel pin. I place the piece with the hole in the collet on the mill and move the table until I can gently get the dowel pin into the hole with the quill.

                      There's probably smarter ways but I devised this one for aligning a mold on the rotab that couldn't have more than a 1/8 hole drilled there. This was part of a setup that allowed me to mill 1/8 o-ring grooves with rounded corners right near the edge of square part.

                      --Cameron

                      Comment


                      • #12
                        Originally posted by Frank Ford
                        If you mean the low profile ones I'm using to hold the aluminum round in the article, those are "toe clamps," and they are really cool, but kinda spendy. McMaster-Carr has them at the bottom of Page 2559 on their online catalog.
                        Yikes - well, they are definitely proud of those things. Still looks like a good thing to have, though, for the shaper, particularly. Better check the bank...

                        Comment


                        • #13
                          Quick and dirty setups

                          I am a fan of quick and dirty setups for jobs of relatively low precision. I go along with Frank and Cameron's methods for aligning parts, chucks, and rotabs. I have a collection of precision dowel pins, salvaged from jobs when I worked in tool and die, that go from 1/8" to 3/4" in diameter. Two each allows me to cover a lot of situations. If you have a precision job, you just use the quick and dirty to get you in the ballpark and then use the indicator to get it down to dead nut/right on.
                          Jim (KB4IVH)

                          Only fools abuse their tools.

                          Comment


                          • #14
                            I made a set of circular inserts for my Rotab (griz 8 in)

                            My rotab has a ~1/4 deep by ~1.125 dia recess in center, before Morse taper starts.

                            I turned a piece of Alu to proper OD, Drilled and bored to 1/4 id for a centering hole..

                            Faced that off, bored 3/8, 1/2 5/8, 3/4 etc

                            Even faster because I don't have to change collet or endmill holder

                            Just pop in center adapter, turn end mill over, center, clamp.....

                            If needed, drag out the DI for fine work...

                            Also allows for rough centering of parts (pin in adapter hole) with common size center holes. shouldered pins easy to make for specials...
                            Last edited by Bguns; 11-10-2009, 07:05 PM.

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