Limit switches for cnc

Using Arduino General Electronics
1

what is the common practice for limit switches on a cnc machine using arduino+cnc shield
NO ot NC as my software cant detect them when they are connected
I have them wired up as Normally open (NO) and software is the openbuilds control
and input would be welcomed

2

  • Most are N.O.

  • If the wire breaks, however, there is no error detection :sob:

  • N.C. on the other hand can detect an open wire, however, not a shorted wire. :sob:

  • A N.O. with a parallel 1k resistor (for supervision) (or N.C. with series 1k) is a good option; an analog input would be used . . .

3

Common practice is no limit switches. Use a switch to indicate the ZERO position of each axis. The CNC code should know what the limit is for each axis in number of steps from zero.

4

:thinking:

  • Limit switches can be dual function, the Start switch and the Crash switch.
2 Likes
5

Limit switches have contacts which will corrode in time. Unless rated for dry switching they need some current so they will clean themselves. I use a minimum of 1 mA through the contact prefer more if possible. Switch configuration was determined by the actual application.

1 Like