You connect your Printrbot, click "run" or "start" in your software, only to watch your hot end dive right into the bed and drag itself in circles. It can be very frustrating. The good news is that the probe is probably functional. Try these troubleshooting steps to identify the problem.
1. Make sure that the probe is properly calibrated. If you have not gone through this process, please do so. Calibration is ABSOLUTELY necessary for your bot to function properly.
- Click here for a video tutorial on calibrating your Auto-Leveling Probe.
- Using Cura to Calibrate Your Auto-Leveling Probe - Printrbot Play
- Using Cura to Calibrate Your Auto-Leveling Probe - Printrbot Simple
- Using Cura to Calibrate the Auto-Leveling Probe on Your Printrbot Plus
2. Check for mechanical problems. For instance, if the Z coupler is not securely attached to both the motor shaft and the threaded rod, the motor will spin without raising the print head. The threaded rod should also be securely pressed to the motor shaft by the Z coupler.
Other possible mechanical solutions
- Power your bot on. Hold something metal (screw driver, knife blade, etc) directly under the end of the probe and see if the light on the top of the probe lights up.
- Check your probe extension wire. Always match the wires from the plug end of the cables (as if the probe were being plugged straight into the board) before plugging them together. Do not just assume that matching the colors is the correct way. In the picture below, you would actually connect the black cable on the left plug into the red wire on the right plug.
- Check your wiring for fatigue or a stress point. Move the extruder just above the bed close enough for the light on the probe to turn on. Move the bot around as well as the bundle of wiring coming off the extruder and see if the light goes out at any point. It it does, find the break in the wire and replace the part.
- Make sure that the probe has not moved over time. Through movement and vibration, the probe may have shifted after the nuts holding have loosened. You may need to tighten those nuts and re-calibrate your Z probe.
- Also check to make sure you hot end is not loose. If your hot end is not secure, it might drop far enough to make contact with the bed.
- If you have a Rev F board, make sure the probe voltage select jumper (pin connector) is in the right location or not missing.
3. Perhaps the problem is in your software settings. Download the gcode file (FirstCube.g) attached to this article and use it for testing/calibration. By using pre-generated gcode, you take your own settings out of the equation, to further isolate the problem. If you run the "FirstCube.g" and see the same behavior, you can begin to focus on more mechanical issues (wire fatigue, mis-wired connection, faulty part, etc).
4. Speaking of gcode, make sure that you are adding the right settings into your start G-Code when slicing. You need to add a homing feature (G28 X0 Y0 Z0). This will start your printer moving to the home position on all three axis. You not only need this to print your object from the right spot, but this also brings your probe close enough to the bed for it to read the metal. The second thing you want to add to your start G-Code is the probing feature (G29). This will command it to probe the bed in three locations in order to find the plane the bed sits on. If this is not done, it can cause the same issue of running into the bed or it will not be working properly.
Check this in Cura/Start-End-GCode