Re: [CAD_CAM_EDM_DRO] Re: Reed switch for limits - anyone done it?

On Sat Aug 17 12:44:50 2002, mszollar, <kenargo@...> 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

--
----------------------------------------------------------------------------
RKBA! ***** Blessings On Thee, Oh Israel! ***** 4-19!
----------------+----------+--------------------------+---------------------
An _EFFECTIVE_ | Insured | All matter is vibration. | Let he who hath no
weapon in every | by COLT; | -- Max Plank | weapon sell his
hand = Freedom | DIAL | In the beginning was the | garment and buy a
on every side! | 1911-A1. | word. -- The Bible | sword.--Jesus Christ
----------------+----------+--------------------------+---------------------

Constitutional Government is dead, LONG LIVE THE CONSTITUTION!!!!!

----------------------------------------------------------------------------