Re: Home/Limit switches : Micro switches or optical interrupters?

Erik,

This may be a case where an electromechanical switch is best. Hall
sensors are temperature and stray magnetic field sensitive. Reed
switches are also stray magnetic field sensitive. Opto inrerrupters
are light, dirt and temperature sensitive. The exception is
the "index" pulse on an optical encoder. There a home switch closes
when the motor is within 1 turn of the home position. The encoder is
then turned until the index channel goes high. Very accurate.

Mariss

--- In CAD_CAM_EDM_DRO@y..., "Erik Reikes" <ereikes@r...> wrote:
> I am slowly but surely progressing on my servo CNC conversion and I
> have come to the question of limit switches.
>
> Are most people using micro switches or optical interrupters to
> determine their home position? What kind of repeatability in home
> position is required/attainable?
>
> Micro switches seem like they would be easier to implement while
> optical interrupter probably have greater accuracy and no moving
> parts. Right now I am leaning towards optical interruptors with a
> small tang mounted on my table to trigger the interrupter, but
> thought the list might have some thoughts on why microswitches are
> the greatest thing since sliced bread.
>
> TIA
>
> -Erik Reikes