16374Re: Column Moving Up
- Dec 1, 2006--- In email@example.com, "bob_kellock" <bob@...> wrote:
> --- In firstname.lastname@example.org, "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 youcan't
> > swing the head, but I've never felt the need to. To make itreally
> > accurate, I suppose shimming to remove any side play wouldwork,
> > but my side play is negligible, and has not caused me anyproblems
> > so far. You just have to make sure the rack is truly verticalwhen
> > fixing to the column.that
> > 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 rackwhile
> tightening the pinch bolts, you should achieve acceptableneed
> 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)as,
> without it, the rack would bend when applying the twisting force.I
> estimate that to be about 0.001" at the spindle per pound force.significant
> Small holes drilled or tapped in the column would have no
> effect on its strength.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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