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New buidl printer - Z axis pushing past stop switch

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    New buidl printer - Z axis pushing past stop switch

    Hi Everyone. I am a complete noob here. I am not even sure what I would search to find a solution to this problem.

    Basically I have bough and constructed a printer I got off Ebay. 2018 NEW 3D Printer Prusa i3 Reprap MK8 DIY Kit MK2A Heatbed LCD Controller CTC

    It seems to be ok when auto homing. The z axis is causing me no end of trouble though.
    When I level the bed and then get the printer to print from the SD Card. The printer will run the print head down into the glass plate, to the point where the steppers start to skip. The stop switch is at breaking point at this stage.

    I can't seem to get the printer to stop doing this. Could anyone offer some advise as what to look for.

    Here is some information that I figure would be useful.
    The z stopper is at the bottom and is connected to Z_Min. The board is a 2560 REV A.
    I am try to print this.
    I used Slic3r to create the Gcode. I filled it in with what I though was the correct values. If you tell me what you need I can try find the settings.

    Thanks in advance.

    If you did your bed calibration right, The print head should not be crashing in to the bed, how ever you could be having other problems . Good Luck


      The problem is not in what you print. Raise the z up manually about 150 mm then do a home and press the stop with your finger it probably won't stop. On the stop switch there are two wires that go to the board. Look at the switch you will see writing on it C NO NC if they are not soldered on swap the NC and NO wire and and try it. If they are soldered they are most likely hooked right. Next thing look at where it connects to the board as see if it simply connects only one way. If it gives you two choices connect it to choice two. Otherwise it is a configuration issue in firmware on sd card. One other thing to look at is stepper connection if you can flip it 180. A pix of board would help. Look at printer info tab for the firmware. Try this site


        I agree with Roger3D, you've got a problem either with the switch or how its connected on the board. Ran across the same issue due to cheap end stop switches.


          Hi All,

          Thanks for the replies. I finally figured out the issue. It turns out that one of the stepper motor drivers was dead on arrival. No matter what you told it to do it would make the motor turn in one direction.
          Out of pure luck it happened to get attached to the Z axis.

          I have since replaced the driver and the printer is working great now.

          For anyone else that may have a similar issue.
          I managed to find the problem by learning about the G code that the printers use. I then found pronterface which allowed me to manually issue commands to the printer.
          Once I managed to get into the printer via the serial port using pronterface, I just moved all the axis with the G1 commands.
          It became immediately obvious when I managed to move all the other axis in both directions but the Z would only go down.

          Changing the broken stepper motor driver to another axis confirmed it was the driver that was the issue.

          I ordered a whole new set for 14.50 (5x drivers).

          Now time to print a part cooler


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