Re: [CAD_CAM_EDM_DRO] Lighted edge finder

Hi,

I can't see why thee would be a problem insulating the edge-finder rod from
the chuck. If you used one of the 'older' plastics like Tuffnol, paxolin or
bakelite, these are hard enough to withstand the kind of loads you would
expect on an edge finder without deforming. I believe the commercial ones
use a probe which actually moves until it makes a circuit - perhaps
something like a tube with a springy wire fixed concentrically in the middle
and extending out of the tube a little way. The tube and wire to be
insulated both from the machine and each other. In use, the end of the wire
is used as the edge finder and is pushed across until it completes the
circuit with the edge of the tube. Calibration of this might be a bit of a
problem but the basic idea can probably be developed!

Ian
--
Ian W. Wright
Sheffield UK

----- Original Message -----
From: "Jon Anderson" <janders@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: 06 October 2000 20:15
Subject: Re: [CAD_CAM_EDM_DRO] Lighted edge finder


> Ron,
>
> Before getting a 3/8 thread on tool holder from Sherline, I used a .250
> dowel pin in the holder. Connected a test lead from this pin to the body
> of my electronic edge finder. Another test lead connected the .200 dia
> tip of the edge finder to whatever I was trying to locate to.
> When the dowel pin touched the part, the circuit was completed.
> I've since used this trick with my Bridgeport when I had to pick up a
> reference from the edge of a slot too narrow to get an edgefinder into.
>
> I use both electronic and traditional edgefinders. For most work, the
> lighted types are quick and easy. But, there is just a touch of runout
> on mine. If it's gotta be as close as I can get, I use my "old
> fashioned" Starrett edge finder.
>
> Jon
>
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