View Full Version : Inductive proximity sensor failure

Adrian Hill
06-13-2011, 5:07 PM
My X axis proximity sensor decided this morning that its going on stike. The switch is supposed to stay latched while the metal plate is close enough (over it). once the X & Y axis homes are detected the carriage moves off and the sensors release the circuit (well that's how it should work) - The sensor holds the circuit for about 2 seconds and then releases, which of course causes the carriage to crash into the sideframe.

Anyway, I have'nt been able to source a suitable switch and the machine needs to run - so I devised a devious plan. I've detached the output of the sensor from the control board. The carriage is moved to the X home by hand and the home circuit is bridged to ground on the controller. We turn the machine on and the wife watches the carriage and after the X,Y home has been set and the carriage moves off I release the "Manual home sensor relay" aka Me. This works well for the moment. The problem is now to find a suitable sensor or to replace the inductive switch with a simple mechanical industrial limit switch.

It is astounding how expensive an inductive proximity switch is. It cost about 6 x as much as a mechanical limit switch used on a CNC machine.