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1589Re: [mlathemods] Re: live center woes

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  • Peter sanders
    May 1, 2006
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      Hi

      On Mon, 01 May 2006 18:54:01 +0800, David Lee <dsleeI@...> wrote:

      > A live center turns with the work.

      Precisely, though perhaps a misnomer, a live centre is (can be) mounted in
      the tailstock. A live centre in the headstock though turning with the work
      is really not rotating about the workpiece per se.

      This has been a misnomer for many years. Though it could be percieved to
      be a common error, I was taught MANY years ago and then, as now, refer to
      rotating centre in the tailstock as a live centre ( just like you and
      other US citizens refer to them as centERS whereas we English - now an
      Aussie - refer to them as centRES)

      Though a centre in the headstock is effectively rotating it is stationary
      relative to the workpiece, whereas the centre in the tailstock, if a LIVE
      centre really IS rotating :D if not a live centre then it is NOT rotating
      so is therefore a DEAD centre :D

      Personally I prefer the perhaps misnomer reference of a rotating tailstock
      centre being referred to as a live centre, and was taught and have used
      this reference since 11 years old in technical college (in Liverpool UK) I
      am 56 now, but each to their own.

      Though this maybe the wrong reference, personally I think it has become
      the preferred meaning.

      A search for a reference to live or dead centres brings forth a myriad of
      descriptions many of which can still be misconstrued.

      from

      http://process-equipment.globalspec.com/Industrial-Directory/live_center

      selected at random

      Live Centers (20 companies) Live centers are used to hold or support a
      work piece in a lathe or other machine tools - often between the headstock
      and tailstock. Live centers revolve with the work, while dead centers are
      stationary. Learn more about Live Centers

      Dead Centers (14 companies) Dead centers are used to hold or support a
      workpiece in a lathe or other machine tool. They do not revolve with the
      workpiece. Learn more about Dead Centers


      The part about "Live centers revolve with the work, while dead centers are
      stationary." just confuses the issue :D as the association of revolve with
      the work can refer to a rotating centre in the tailstock just as well as
      it can refer to non rotating centre rotating in the headstock.

      Personally I understand and prefer the reference to a live centre as a
      centre that has the ability to rotate its centre point, while the body is
      held stationary.

      > A dead center is in the tailstock. A
      > turning center turns with the work and is mounted in the tailstock.

      IMHO the reference of "turning centre" does nothing to resolve the issue,
      and in my experience is a term very rarely used I have never heard its use
      in general.

      >
      > David Lee
      >
      > ----------------------------------------------------------------------------
      > ----
      >
      > -----Original Message-----
      > From: mlathemods@yahoogroups.com [mailto:mlathemods@yahoogroups.com]On
      > Behalf Of ndhr23a
      > Sent: Saturday, April 29, 2006 11:01 AM
      > To: mlathemods@yahoogroups.com
      > Subject: [mlathemods] Re: live center woes
      >
      >
      > The length of the taper in the small lathe tailstock is smaller than
      > the normal Morse taper and many commercial tapers will "hit bottom'
      > before they seat, especially ones with tangs on them. Also, the
      > tailstock is designed to push out or eject the taper when it is fully
      > retracted. Try extending your tailstock quill some to see if the taper
      > will now seat.
      >
      --
      Regards

      Peter

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