Quote Originally Posted by JonnyFive View Post
I haven’t looked at the data sheet for the sensor but. I’d assumed that it would be triggered 2 or 3mm before contact and I could then have the hard stop almost flush with the sensor z. How much overrun should I allow for? I guess when it’s travelling at speed something like 5-10mm would be better?


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You need about the same length as a piece of string! All depends on the weight of the gantry, your approach speed for homing (crashes at rapid speed will hopefully be avoided by soft limits once the machine is homed which is the first thing you will do after switching it on) and some stuff to do with drivers that other regulars will understand better than me.

Your Z and other axis (it's Y on my machine but X on many) sensors are right. In practice the overlap of the sensor and your target will not be very much when it triggers. I put slots in the mountings of my targets to make things adjustable but this does increase the risk of something moving and messing up the repeatability of homing.

Kit