Re:Home Switches

I do not believe backlash has anything to do with this.
As long as you aproach the switch from the same direction
every time backlash will not contribute to the repeatability
of the trigger action.
What you could do to test this is mount a dial indicator in
the spindle, home the axis then move a fixed amount off touching
with the dial indicator against a fixed object mounted to the
table.
Zero the indicator there and repeat homing several times
noting the reading on the dial the varietions you get will
indicate the repeatability of the switch.
These Switches come in several grades what you want is a
precision microswitch.
Good Luck


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dave Fisher" <dave@d...>
wrote:

> On fitting home switches to our router table, I notice that each

time

> I home the table - the X and Y readings differ greatly, some times

upto + -

> 0.5 mm. Seldom never going to zero. Slowing the home traverse speed

seems to

> make little difference.
>
> I would have expected there to be some differnces caused by

backlash etc but

> not as much as I am getting.
>
> I have used good quality lever type micro switches, but wonder if I

am

> suffering from switch bounce or just the mechanical properties of a

micro

> switch. Would I be better using a slotted opto coupler to eliminate
> mechanical tolerences or any other method ?
>
> The table is being driven with Rutex Amps and The Desk CNC sofware

and

> controller.
>
> Any advice would be appreciated
>
> Rgds to all
>
> Dave Fisher