Re: Reed switch for limits - anyone done it?

Before I decided to go full CNC, I toyed with the idea of using a
mouse LED/detector to indicate points to stop. That way, I could
just write some ladder lodgic for a PLC.


The idea is to have a fixed point, just a bent pieces of sheetmetal,
and a second that was bolted to the first. one would make a small
window between the two pieces by sliding them together.

Hold your hands flat, thumbs to each other and slide them together
until ther was a small space between your hands. like, that , then
just bolt them together and when the LED passes the gap, bingo !

harder to get simplier than that and all the parts are RadioShack
stuff.

Dave

--- In CAD_CAM_EDM_DRO@y..., Bill Vance <ccq@x> wrote:
> On Sat Aug 17 12:44:50 2002, mszollar, <kenargo@v...> wrote:
>
> >I'd like to thank all that responded, the good news (in my case)
is
> >near 100% of that I mill is Delrin and Aluminum; neither of which
> >has much magnetic properties. I was planing to place the switches
> >against travel to shorten the contact time with the magnetic field
> >(it should also increase accuracy). I'd love to use hall effect
but
> >there is a bit more electronics needed and for a Sherline that may
> >be overkill (but it would be more accurate).
> >
> >At the same time I was considering optical (using laser LED and
> >detector). Very accurate but need mouting is a challenge and the
> >additional electronics as well. There is the cost and its only a
> >Sherline.
>
> Y'know most of the laser set ups I've seen mentioned heretalk about
using lasers
> in dopler shift mode for precise location of the table, but if what
you want is
> an end of travel indicator, there is a simpler way to use them.
The laser
> diode, or even just an LED, could be mounted anywhere, and the
light piped to
> wherever its needed with some fiber-optic line. If it's pointed in
a direction,
> say 45 degrees off axis, the detector input could be run through a
thin piece of
> glass wrapped in foil. The glass might be the type used on a
microscope to hold
> the sample, and alighned with the axis, so that it acts as a go/no-
go style
> detector as the beam hits the side edge of the glass. It would
look sorts like
> this:
>
>
> _____________ foll
> ============= glass <-- Detector input unit
> _____________ foil
>
>
>
>
> _____________________
> | ____________
> | /============ ---------->
Detector/circuitry
> Table | / ____________ ^
> | / |
> <-- travel --> | / <----- Light beam ---+
> |/
> _____________________|
>
>
> As the table moves Left/Right, the beam moves Up/Down across the
glass, which
> lets it through to the detector as it reaches the table's end of
travel point.
>
> Bill
>
> --
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