I do this on my lathe. I use a LED/sensor out of an old ball mouse with a semicircular flag on the motor that is about 1.5" diameter. The output of the sensor is open collector(switches to ground). This is in parallel with the home switch. The home switch is normally closed.
Homing proceeds as follows: While the axis approaches home, the home switch holds the input low. When the axis is nearly at home the home switch releases but the flag is phased so that the sensor holds the input low. Finally the edge of the flag interrupts the beam so the input goes high. If I home slowly, I get repeatability within +/- 1 encoder count (this is a servo machine but the encoder does not have an index). Les Kirk Wallace wrote: > I have thought about this, but I wonder how accurate these are. If you > want to resolve .0002", I think you typically need angular accuracy > to .16 degrees. I guess I could try it to find out. > ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
