the scale mounts are fastened to one part of the assembly. and that assembly is fastened to another assembly.
the DRO will not see movement in all ranges.
try this test.
take a dial indicator to the drill press.
chuck up a 1/8" drill bit. something nice and small.
put in a block of wood or plastic, something soft.
bring the quill down to the work, set the indicator between the table and the head.
now, with some mild force, put some pressure on the block. think how much force you might use drilling a 3/8" drill bit into steel.
watch how much the indicator moves.
try that on the mill. the mill is much more ridgid, but no DRO will ever measure that movement.
Dave
--- In GrizHFMinimill@yahoogroups.com, gerry waclawiak <gerrywac@...> wrote:
>
>
> I can't quite see why you should state total disagreement as a proper DRO will give relative movement of the table in relation to the tool and automatically compensate for back lash in the mechanism to the accuracy and resolution of the DRO which in the case of most cheepies that hobbyists use will be within a couple of thousandths(")
>
> If the accuracy you are looking for is less then you should have no need to mic parts repeatedly or consider many of the other things you mention for small batches once you have produced the first acceptable part.
>
> I use this technique to produce batches of model train wheels etc quite regularly and the accuracy between parts if fine for purpose.
>
> For ultimate precision as you say use of a mic will be required to allow for most or all of the other variables you mention.
>
> Gerry
> Leeds UK
>
> ________________________________
> > To: GrizHFMinimill@yahoogroups.com
> > From: dave_mucha@...
> > Date: Tue, 6 Dec 2011 12:13:30 +0000
> > Subject: [GrizHFMinimill] Re: digital read out from Rockler ?
> >
> >
> >
> > I have to totally disagree.
> >
> > the DRO allows you to get close, fast. you do not have to count handle
> > turns, just watch the numbers rolling by.
> >
> > a 1/4" 2 flute end mill OD is not the same OD, nor will it cut the same
> > slot as a 4 flute.
> >
> > with indexable inserts, the radius has to be allowed for. as does tip
> > wear, and machine play and machine/part/tool temperature.
> >
> > you rough in with the DRO, you finish with the mic's.
> >
> > using a DRO with 0.005" readout would speed up most work by orders of
> > magnitude. the skill is in the finish and that is operator ability.
> >
> > IMHO, the DRO is a simple tool. it can be calibrated to achieve
> > superior accuracy, but at some point it will be more accurate than the
> > machine. and if the machine goes from one end of it's play, to the
> > other, it could easily be a couple thou. the DRO would never know it.
> >
> > Dave
> >
> > >
> > > The reason for DROs is so that you can make accurate stuff *without*
> > > measuring with mics, and so that bend, springback, slop, mounts, screws
> > > and bearing errors are eliminated.
> > > DROs are really good and useful, precisely because they allow one to
> > > actually get to 0.01 mm accuracies, easily, fast, and without measuring
> > > with mics.
> > >
> >
> >
> >
>
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