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Non-CNC trunnion table?

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  • Non-CNC trunnion table?

    I sometimes need to mill features on one side of an enclosure that are related to features on another side. e.g., a connector hole on the front that has to be offset from a mounting boss on the bottom. I'm doing this on a mini-mill and the parts I'm working with are large enough that they don't fit in a vise in all orientations.

    Right now I have two fixture plates to hold the enclosure in the two orientations I need, but it's slow (and error-prone) to pick up a registration point after moving from one side to another.

    I'm planning to make a sort of rotating tooling plate for this so I can drill/mill holes in one side, then rotate the entire assembly 90 degrees without losing registration.

    I know that CNC machines use trunnion tables do do similar tasks. Is there something like that for non-CNC mills? I have a design for what I need in mind, but it would be nice to see what has already been done so I could incorporate ideas other than my own.

  • #2
    90 degree bracket on a vertical rotary table?
    Universal dividing head with a tooling plate?
    Condense it down to a single jig and use pins to locate in the second position?


    • #3
      Lane made a really nice trunion table -- I'm pretty sure it was featured in HSM magazine. I'll look it up when I get home...
      "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."


      • #4
        Check out ( Book Two ) The Best of Projects In Metal .Put out by the Village press . Page 138. . That is all the help I can give.
        Every Mans Work Is A Portrait of Him Self


        • #5
          High tech systems makes a trunion table that is cut to match the sherline rotary table.

          With a little adaptation, you could use it on different mills. Also look at the modular work holding system based on the same plate used for the trunion table (by the system, not just the plate).

          Note that I would recommend getting the CNC version of the sherline rotary table as the CNC version can be used manually but the manual version can't be upgraded to CNC using stock parts. The shaft ends on the pinion gear are different and the worm gear and pinion have to be cut together. You can even get the sherline manual one axis controller for the rotary table and do your 90 degree rotations with a push of a button instead of 18 cranks, but buying an incomplete CNC system with only one axis driver would be a better investment. Add a second axis (X) later and call it power feed. Third axis (Y) and now you have a second power feed and XY positioning to hole locations (programming for this is dead simple) with manual quill feed for drilling. Add a fourth (Z) and you have automatic quill feed and four axis CNC. Add a 5th axis and another rotary table and you have 5 axis CNC. This is the pay as you go method of working up to full CNC.

          Of course, you can build your own trunion table mounting brackets.

          For the original job you described, if you are making many parts all you may need is a simple work stop to align the parts quickly before and after flip once you have done the setup.


          • #6
            The current setup was put together as a quick and dirty solution and not expected to last very long. So I'd rather not make modifications to it, but instead move on to something more flexible.

            A rotary table with a bracket would probably work just fine: the vertical fixture I'm using now is only supported at one end, so I know that's sufficient. But my tool budget is allocated to more pressing items right now and a nice rotary table costs more than I can spend at the moment. However, I do like the concept. I'm going to try doing something like that with a spindexer. I should be able to prototype it in less than an hour.