machine changes referance position

[sab]

hi
i have a problem with DAHLI MCV 1350 that whenever machine is referenced its x axis reference changes i.e some times machine is referenced before reaching the actual refernce position & some times it gets overtraveled.Is it a problem of limit switch?

[Alex S.A]

it is possible the switch is failure, bad contact is a commun problem, but I would check if the wiring of switch is in short with machine other cause could be the encoder the rate chance is too low to be the encoder.

[Alan B]

Assuming the machine has a slowdown cam for reference, i:e rapids then slows to reference the slowdown switch is probably sticking. When the control sees the slow down switch it then looks for next zero from the encoder, If the switch sticks it will miss the first zero and see it on the next revolution.
Alan B