Bridgeport Series II Interact 2 CNC Mill ==> Lathe Chuck

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  What I did was, I used a QC30 tool holder with a thick "neck" for a
  large diameter end mill, 3/4 or so, I do not remember. I took a round
  piece of steel, bored it on the mill to the diameter of the "neck",
  and drilled holes to bolt on the chuck.

  Then I put the bored round piece on the toolholder and welded it with
  7018.

  It was not perfectly straight, as I expected. But then I put the
  toolholder into the spindle, spun it, and trued it as it was mounted,
  which, not surprisingly, gave an excellent result.