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16374Re: Column Moving Up

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  • Conrad_G
    Dec 1, 2006
      --- In mill_drill@yahoogroups.com, "bob_kellock" <bob@...> wrote:
      > --- In mill_drill@yahoogroups.com, "Conrad_G" <conrad_g@> wrote:
      > >
      > > Hi - new member here - yes, i fixed my rack with two screws and
      > > roll pin some years ago, and I find it works OK - so you
      > > swing the head, but I've never felt the need to. To make it
      > > accurate, I suppose shimming to remove any side play would
      > > but my side play is negligible, and has not caused me any
      > > so far. You just have to make sure the rack is truly vertical
      > > fixing to the column.
      > >
      > > Cheers - Conrad in Houston.
      > >
      > I'm slightly surprised that that works well enough.
      > In the case of my RF25 clone, with the rack clamped to the column
      > (using G clamps), there is about 0.050" slack at the spindle. The
      > edges of the rack are unmachined and it is slightly bowed.
      > If one edge of the rack was machined and it was fixed rigidly and
      > truly vertically to the column then, if the head is twisted so
      > its slot is held firmly against the machined edge of the rack
      > tightening the pinch bolts, you should achieve acceptable
      > registration.
      > As well as fixing and locating the rack at both ends you would
      > to locate it near its middle (using, for example, a blind dowel)
      > without it, the rack would bend when applying the twisting force.
      > estimate that to be about 0.001" at the spindle per pound force.
      > Small holes drilled or tapped in the column would have no
      > effect on its strength.
      > Bob

      Bob - that's just the way I have it - my rack was not bowed, and I
      fastened it at both ends with a pin in the middle, and when raising
      or lowering the head, I keep pressure in one direction only on the
      side of the rack, and so far have had no problems.
      Cheers - Conrad
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