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Spin Index Runout

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  • Spin Index Runout

    I have a chinese spin index that I was using on the mill today. While lining it up, I checked the runout one inch out from the collet and found it to be 0.0007" TIR. While this was acceptable for the task at hand, I thought it would (might) be better (on the lathe, the same collet and test bar come out to about 0.0002" TIR). I went to the Suburban website

    and it looks like their published runout is 0.0005" TIR ( I am assuming this is one inch from the face). Does anybody have any real world numbers for their spin indexers?


  • #2
    Were you checking on the spindle or on the work mounted in a collet. I'd expect that Suburban is quoting spindle runout. Add a collet, which almost never has zero runout, and your number will increase. I've never measured mine, so I am really not much help.


    • #3
      The Spindexer run-out is quoted stand-alone on the 5C taper.

      Putting a collet in it can either have the collet eccentricity/error add to or subtract from the error in the spindexer depending on where the collet error (max) is in regard to the spindexer maximum error position.

      That being so, it suggests that the collet error can be reduced by re-positioning it in the spindexer.

      Not all collets in a set have the same error.

      I could get by easily with a work error of 0.001" so 0.0007" is OK for me.


      • #4
        when ever i see someone complaining about the "runout" of this or that collet or machine....
        I remind myself the adverage adult hair is about .004 so anything less is really about spliting hairs and plenty close enough for me


        • #5
          I should point out that there are two types of "run-out" which may exist together or seperately:

          1. "parallel" run-out where the run-out is "cylindrical" (like a parallel rod) - same run-out from end to end on the test-piece; and

          2. "conical" run-out where the run-out is in the form of a cone and varies over the length of the test piece.

          The total run-out can be varied:

          --- by changing the position of the collet adaptor in the mill/lathe spindle and/or:

          --- changing the position of the collet in the collet adaptor.


          • #6
            Sounds like my spin index is just fine. I would describe the runout I had as "conical" because at 4 inches from the collet, the runout was measured at about 0.003". I played with changing the position of the collet to the spindle and the work piece to the collet and was able to get it down to 0.0005" at one inch from the collet face which looks like it is pretty good.