Homing X and Y OK, but Z only moves downwards from current bed position

[Deleted User]

I am having a problem with an Enjoy 3D Printer. I am using Repetier-Host 2.2.4 and Repetier-Server 1.4.2 on Linux Mint. When I attempt to home the print head, the X and Y homing seems to work correctly, but the Z direction behaves strangely. It will simply move the bed downward a few millimeters every time homing is commanded, and will continue doing so until it hits the bottom frame of the printer.

This printer was working fine until a couple days ago where I had some problems with the extruder and had to clear the nozzle. I am unsure if that has anything to do with this problem.

I'm very new to 3D printing so bear with me as I learn. If more information is needed I will provide it. Thanks for your help.

Repetier

This is a printer issue and not a host issue.

For me it sounds like the z sensor is always triggering high. Try
M119
to see the endstop status in console. If bed is not close to nozzle it should be low/off. At correct z=0 it must be high.

If the printer uses a z-probe that is also used for bed leveling the signals come from z-probe not z end stop. Then it depends on the type how long it signals high (some do only a few ms) but as soon as printer firmware sees high signal it stops move toward extruder.

[Deleted User]

This is the output of M119:

x_min: TRIGGERED
y_max: TRIGGERED
z_min: open

I do not know whether a z-probe is used or not, but the customized Repetier-Host software that came with this unit (only works in Windows) included g-code to manually move the bed to set the nozzle distance from the bed using a sheet of paper as a feeler.

I deleted the printer settings in R-Host and R-Server, and reconnected R-Server and entered the bed dimensions and nozzle settings during setup, and am importing those settings into R-host. Homing behavior did not change, still goes down. However, it is making some noise for a time after the bed stops moving, but the z-axis screw isn't turning after it moves the bed down. The bed isn't against any stops, and I can move the screw manually by hand very easily in both directions, so it doesn't seem to be a mechanical binding problem.

[Deleted User]

Another bit of information (maybe) - there are 3 LEDs labeled X, Y, Z that seem to be associated with home limit switches. I can manually move the bed in the X and Y directions and when I hit the X and Y home limits ( I can hear them click when they close) the X and Y lights illuminate, and M119 shows X and Y are triggered. When I move the bed off the switches, the lights switch off, and M119 shows X and Y are open.

However, the Z light is always illuminated, even when M119 indicates it is open.

I'm unclear on how it works, but there is a screw on the top of the printer head that was used during a calibration process during setup with the original manufacturers customized R-Host software described here (pages 35-44). I imagine there must be a switch in the printer head itself.

https://www.86duino.com/86Duino-Enjoy/86Duino_ENJOY_QuickStartManual_V2_0_EN.pdf

I'm unsure if it is relevant but I'm wondering if that screw shifted when I was wrestling with clearing the blockage.

Repetier

If you check docs about leveling you see them mention the screw and how changing it can make the led turn on/off. Not totally sure how this works 100% but you have no z probe, so far is clear. When led is on M119 should show triggered. If the z switchis integrated in extruder head it is possible that you need to change the screw to physically be able to trigger the switch.

[Deleted User]

With the printer offline and cold I pressed up on the nozzle and could hear the switch click in the printer head. I turned the adjustment screw until the z LED just shut off (from the procedure in the printer manual). When I did this it seems to home properly now.

I guess if the screw is adjusted such that the switch is opened, it thinks it is crashed against the bed and moves the bed away to try to remedy it. The screw adjustment seems to set the sensitivity of the switch to touching the bed.

Learning more every day. Thanks for your help!