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Workholding on a Rotary Table ?

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  • Workholding on a Rotary Table ?

    What are the general methods for holding work on a rotary table ?

    Would one mount a 6 " or greater disk on a 4 " table ? Does the table size determine the largest size disk one can mount ?
    If I wanted to buy a rotary table, would you buy the largest you can handle and which would fit on your mill ?

  • #2
    Generally we use T-nuts and screws, but adaptor plates hardly reduce rigidity of the setup. So you could go 4" rotary table to a 6" adaptor, to a 5" chuck.


    • #3
      Originally posted by TR
      If I wanted to buy a rotary table, would you buy the largest you can handle and which would fit on your mill ?
      Yes. Depending on what mill you have, an 8" is basically the max for one man to lift, mount and dismount alone due to weight. Even with that said, it is a bit cumbersome.

      I would not say the table diameter is the largest workpiece you could mount. I made an adapter plate that bolts to my 8" rotary table and mounts a 10" 4-jaw chuck. That said, a 4" may lack the rigidity to mill much larger than 4" diameter. If you're on the fence, I would recommend at least a 6" diameter unless you have a very, very small mill.

      In my experience, workholding is always "interesting" with a rotary table. Remember you must have two mounting points in order to drive the workpiece. I always want to use a centering hole, as I am usually making some sort of concentric gear thingie. Planning where I can mount the drive shaft is mostly a head-scratcher.

      Lastly, often helpful for rotary table work are toe clamps. For example, the low profile strap clamps that can be advanced into the work:


      • #4
        Make 'er fit

        Thanks TR

        A 6" and an 8" rotary table on a HF-45 mill. The "front-face mounted" chucks are 5" and 8" respectively. The face-plate on the 8" rotary table is 10":

        Head-room with the milling head on the HF-45 mill fully up with a boring head in it and a 6" rotary table with a milling vice on it on the mill table. The "white stick" is a 250mm (~10") section of a 1 metre carpenters rule - for scaling purposes:

        A Sieg X3 mill with the head fully up and with a milling vice on the mill table. The "white stick" (500mm ~ 20") is half of a 1 metre carpenter's rule:

        This ER-32 collet adaptor will fit/bolt onto my lathe, both rotary tables and the mill tables as well as my tilting angle-plates etc.

        There is no real stated or mandatory limits as to what can or cannot be attached to or mounted on a rotary table other than space, safety and practical limitations.

        I rarely use my 8" rotary table as it is heavy and awkward and the 6" caters for most of my needs.

        The specifications are here:

        This is my "super indexer" rotary table:

        The 6" and 8" rotary tables will fit on my HF-45 mill where-as only the 6"rotary table will fit on my Sieg X3 mill.

        I prefer the HF-45 mill and the 6" rotary table for every-day work.

        I would not have a 4" rotary table as it is too restrictive as regards capacity and robustness.

        This 170mm (~ 6.5") face-plate fits on my lathe, my mill tables and my rotary tables:

        My mill details - for illustrative and comparative purposes - are here:


        Sieg X3:

        There will be lots of good advice here.

        I hope it helps.


        • #5
          Work on rotaty table

          Clamping equipment on rotary table

          Choose one.


          • #6
            Crowded house

            Originally posted by Forrest Addy
            Work on rotary table

            Clamping equipment on rotary table

            Choose one.
            Good comment Forrest.

            The top of even a 6" rotary table is pretty crowded real estate.

            One of my hopefully not too distant projects is an 8" or 9" clamping plate adaptor for my 6" rotary table - 1/2"+ aluminium plate located on the OD of my RT table and secured to it with M8 socket screws - and with lottsa M8 drilled and tapped holes on it - and with some "vee" concentric grooves for expediting centreing stuff on the plate.

            But following on from your comment, it does not both me one bit if I have to drill or drill and tap a job for a clamping bolt to pass through if needs be and if the job can stand it.

            Shapers have a similar "crowded real estate" problem too. Another one of my projects is to make an extension table - in the form of a "propped" angle plate to secure my rotary table (with a chuck on it) to so that I can get the stroke I need when using the shaper as a slotter.


            • #7
              I have a 10 " rotab and it can get crowded. If you search here, you'll find plenty of pics that can help you out.

              Here's one:

              I bury my work


              • #8
                If it's something that already has holes in it, I usually just whip up a fixture plate for it. Sweep in the head as good as you can get it. Center the rotary table. Make sure it is at 0 degrees. Drill a couple of holes in a piece of scrap aluminum and bolt it to the rotary table. Face your fixture and drill and tap as necessary for your mounting holes. Then machine away on your part. Since you machined everything in situ, then you should be spot on.
                Stuart de Haro


                • #9
                  Excuse the ignorance, but how do you bolt a chuck to a RT? I have a 12" Bison RT and would love to be able to mount one of my chucks on it?



                  • #10
                    Originally posted by Smokedaddy
                    Excuse the ignorance, but how do you bolt a chuck to a RT? I have a 12" Bison RT and would love to be able to mount one of my chucks on it?

                    what's the register in the RT? Mines' just straight forward bore so you could make a back plate for it.....or what i did, replicate the lathe spindle as a bolt on attachment for the RT

                    Years ago I made a D1 3 mount for my RT and one for my indexing head...the idea being i could take something off the lathe and mount it without disturbing it to achieve concentricity. The indexing head one has seen some use, the RT one almost never. They were a lot of work to make and the RT one wasn't worth it.

                    I ended up making a post system - parts with a bore get mounted on a post - as so much of my RT work was rounding and profiling smaller pieces. Its actually very handy, I'll look for some pics

                    TR, the smart alec response to mounting a 6" disk is to use a 12" RT. Trying to do so is on smaller RT is where ingenuity and innovation come in; If there aren't bolt or spoke holes to bolt through, think of bolting a largere plate to the RT and then use strap clamps on it. Frequently with RT work you have leapfrog the clamps to get at all areas needing machining; maybe stating the obvious but keep it in mind, lots of times that's the way to go.
                    in Toronto Ontario - where are you?


                    • #11
                      Like McGyver I use a post system. My RT has a Morse Taper hole in the center. My neighbor who is a machinist made a perfect fitting plug for it. I bored it out on my lathe to exactly 1/2" and bought a length of 1/2 ground shafting and turned plugs in various common sizes and saved some for spares. Works pretty good for me. It also allows me to center the table under the mill by grabbing the plug with the mill before I bolt down the RT.

                      I bought a 10" RT based on comments from some of the crowd around here 3 years ago because of the real estate issue. Now I have to have my wife and all my neighbors and friends over to help me mount it. It don't get used much I keep it nearly at table top height so I don't have to bend over to pick it up. Just go up to. plant your feet, quick sign of the cross and then wrap your arms around it, waite till the oil soaks into our shirt and then swing it over to the mill and hope you forgot to get everything out of the way If I had it to do over again I would have bought an 8" RT and I think it would have gotten more use.
                      Last edited by Your Old Dog; 09-26-2010, 11:37 AM.
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