Added auto z endstop; machine goes to different position to start cutting (randomly)

I recently added z endstop to the machine (one end to a conductive magnet and the other end to a copper PCB). I am noticing two problems:

  1. If I touch the copper PCB with my finger while homing, it registers that touch as a “Trigger” and considers that position as the home (well it comes down slowly for the second probe but again, if I touch the plate, it registers that as trigger". I have connected the plate to signal and also to negative but get the same thing; it triggers at finger tough!

  2. After homing, the machine pauses for me to remove the touch probe and when I resume the print, the machine would occasionally runs to a completely different position and start cutting (like, if it was suppose to start cutting at 10mm x 10mm from origin, it would go to like 70mm x 20mm and start cutting). This is not a programming problem because if I turn off the machine and restart the code, it starts cutting from the correct position. This is boggling my mind! I am guessing this has something to do with the z axis homing.

Anyone experienced this? Any solution? TIA

Do you happen to be running Marlin firmware and Repetier Host?

I experienced similar issues when I installed Z endstop and a touch probe. I can’t really narrow down what causes it, but Marlin and Repetier would get out-of-sync with each other on where they thought the head was currently positioned. There are some posts from the Repetier developers saying that the position reports from Marlin can no longer be trusted, so they won’t rely on them. A work around that has worked for me is to use the G92 command to tell both Marlin and Repetier what the current position is…

I am directly using SD card. Now that you mentioned about things getting out of synced, I am wondering if the display is causing the issue (I sometimes have to push the card in hard in order for the reader to read it; the card is brand-named and fine). I should try few cuts using ponterface and see if the problem persists. Thanks for sharing your experience!