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

|Sounds like a good idea to me. Mount the magnet under the table, no
|worries of steel building up on it. They should be much more accurate
|than clunky mechanical switches. You could even use door/window switches
|from Radio Shack. These are pre-encased with mounting holes, if you
|don't want to use the double-side tape.

While you can use almost anything as a limit switch, home switches are a
different story. As with most components, quality comes with price. For
homing, you want a switch that is repeatable and a software routine that
takes any irrepeatability (is that a word?) into account. The Radio Shack
switches are meant to be used with burglar alarms. They will not have the
repeatability needed to home a mill, although they may be suitable for
limits (I wouldn't use them there, either)

Earlier comments about swarf balls seem to be right-on. Remember, hiding the
magnet from view does not hide its field, and I don't believe that the
aluminum construction of the Sherline would do much to hide the field
either. Swarf is highly intelligent, and having nothing to do but figure out
a way to find your magnets and not wanting to be swept away into a trash
can, will find a way to get to your magnets. It's only a matter of time.

If anything, stick with either a mechanical switch or a proxmity switch. Use
a routine that always approaches the home switch from the same side as its
final movement (example - home is always at the left edge of the switch when
approached from the right).

-- Jerry

|The trick to using microswitches (for those of us who do) is to mount
|them so the roller arm is moved when an overtravel happens, but not in
|the way of the travel.