3D Touch Z axis calibration troubles

[Dan Volpe]

Hi all,

I'm having an issue with the z axis calibration on my machine. When I go into the z offset calibration, it starts to move the print heads and bed around to the offset height. However, the z axis never stops going up (or trying to go up). I had to disconnect the table because even when it crashed, the motor kept turning. When I press the button to cancel, the z axis stops and x and y axes move slowly to the front right corner, then returns to the home position. Checking the position in the move function, the z axis has gotten into the neighborhood of -3000. The z offset is set at 0.0. Pressing the adjustment arrows during the calibration seems to change the z axis height, but does not stop the motor from turning. It continues to turn clockwise no matter what. I thought it might be a limit switch error, but there doesn't seem to be any for the z axis. So it seems to me that it's a software issue in the firmware. I have tried updating the firmware without saving the settings, but that has not worked. Any other suggestions? Thanks for any help.

[Unfold]

Dear Dan,

There is definitely a limit switch on the 3d touch's Z-axiz but it's a bit hidden from view. The magnet that triggers the reed switch is embedded in the printbed (did you replace this with a home made bed?), the sensor itself can be found in the rear X carriage bearing housing. Right behind your extruder pack is a small hole in the aluminium cylinder that houses the bearings. The sensor is down in that hole and sticks out at the bottom (small black cylinder) and it is fixed in position with a little screw. In my machine (the very similar bfb3000) the wires running to this sensor are blue. Maybe the sensor is dead? Try to move a magnet under it and see in manual move if it is triggered at all. You can replace it with a similar one if it's broken.

[Theuns DvSchalkwyk]

Hi, I'm posting a solution to a slightly different problem involving the 3D touch z-axis.

My sensor was working fine (You can test this with a small magnet in the manual-move mode, bring the magnet close to the black sensor while you are moving the axis and it will stop if the sensor is working).

My problem was that someone, possibly one of the 100 students who worked on the machine ;-) set the z-offset to -123. this made it impossible to reset to the a value closer to zero, since the bed first want to go to the position before you can start setting a more appropriate value.

My solution was:

1. Move the bed manual mode to the bottom.

2. Get ready with a magnet.

3. Do home, and immediately use the magnet close to the z-sensor to trick the machine into believing it is home, then let it continue to the offset of -123. Lucky this was within the travel of the Z.

4. Go to the z-offset and set it back to Zero.

5. Redo the setup process to get a proper z-offset (described elsewhere in the the manual I think)

[Unfold]

thanks for sharing! Those rare issues can be a pain to solve.