Re: [CAD_CAM_EDM_DRO] RE: Lighted edge finder

Jon,

Once I locate a corner of the stock, I'm OK. There were times when I
used a jig to hold parts, and generated gcode based on a location on the
jig. The part blank extended past the jig's origin (maybe that's the
problem), and I couldn't get back to it. I've wanted to be able to
re-locate the jig, or a "known" feature on the stock. If I contour the
outside of the part, I've lost the stock's edges.

I don't have a "home" on the Sherline mill, and seldom have a vice or
fixture located the same exact place on the bed. I'd like to be able to
check that the work is still located correctly conveniently. On the
needle, looks like one could just turn a needle point on a piece of
drill rod, and eyeball it to the work, probably as accurately as the
wiggler?

Can one use a dowel pin (shank of a drill bit) to re-locate a same sized
drilled hole accurately? Seems like a center drill will re-locate a
center drilled hole, if you leave the work loose, and lightly hold it
temporarily with the center drill while you tighten down the work (or
make a 60deg end on a piece of drill rod). But that only gives one
point of location, good only for drilling that one spot. Or is that bad
shop practice?

Alan

Jon Elson wrote:

>
> Alan Marconett KM6VV wrote:
>
> > Jon,
> >
> > So you make it fly out? I tried putting the point into a punch mark,
> > but it didn't tell me much. I will wait for the Starrett edge finder!
>
> The technique for a punch mark is different. With the spindle running
> at
> about 1000 RPM, you use a pencil, straight edge or whatever against the
> side of the pointer, and apply pressure until it runs straight, with
> minimal
> wobble. You can then bring the punch mark directly under the point.
> Not a terribly accurate way to locate a hole, but good to .005" or so.
>
> The edge finders are much better (and safer, too) for locating edges,
> but they don't do as well on punch marks. With CNC, accurate
> DRO scales or whatever, you can do a HECK of a lot more accurate
> hole positioning than with a wiggler and scribe lines.
>
> Jon