The Collaborative International Dictionary of English v.0.48:

Mandrel \Man"drel\, n. [F. mandrin, prob. through (assumed) LL.
   mamphurinum, fr. L. mamphur a bow drill.] (Mach.)
   (a) A bar of metal inserted in the work to shape it, or to
       hold it, as in a lathe, during the process of
       manufacture; an arbor.
   (b) The live spindle of a turning lathe; the revolving arbor
       of a circular saw. It is usually driven by a pulley.
       [Written also manderil and mandril.]
       [1913 Webster]

   Mandrel lathe, a lathe with a stout spindle, adapted esp.
      for chucking, as for forming hollow articles by turning or
      spinning.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

mandril \mandril\ n.
   any of various shafts that rotate or serve as axes for larger
   rotating parts. [Written also manderil and mandrel.]

   Syn: spindle, mandrel, arbor.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

mandrel
    n 1: any of various rotating shafts that serve as axes for
         larger rotating parts [syn: spindle, mandrel,
         mandril, arbor]