Things you should know about 3D Touch and BL Touch

3D Touch is one of the easiest things you can get for your Marlin 3D printers who does not have auto bed leveling features. It is cheap and easy to set up and configurate.  You can also find a lot of tutorials and prints for it.

This tutorial I collect some information and tips that you may want to know about it, hope to save you sometime on using it.

Before start, we need to know some basics about it. 

The light)

As it always uses to substitute for the BL Touch and they have slightly difference on connections, telling the diagrams on its chip and make sure to connect correctly.  After that, the lights will help you tell its working status. If you see the red light after the initial set up, you need to check your connection and make sure it’s connected correctly. Blue/purple lights on means it works well.

If everything is right but the problem remains, it is highly likely to be defective.

Distance to the nozzle)

After that, you should make sure its pin is higher than the nozzle and can touch the build plate, otherwise it cannot be triggered properly.

Detection)

3D Touch/BL Touch releases the pin to detect the defined coordinates, then level the bed with offsets. If any of the points was not detected, the extruder will go up and flash red light. When this happened, you need to check the firmware configuration, adjust the coordinates or the print to mount the 3D Touch.

Failed to verify BLTouch probe is raised; retrying.)

When you see “BLTouch failed to raise probe” or “Failed to verify BLTouch probe is raised; retrying” in Klipper, you need to check the pin settings. For 3D Printers who uses KP3 mainboard, it should be “sensor_pin: ^PC4” and “control_pin: PA8”.

Alright, here comes the tips.

Replaceable pins

The pins of the 3D Touch/BL Touch is replaceable. Just loose and remove the screw on its top, you can take the pin out and replace it. The pin may damage during a failed print or wrong set up, but the 3D Touch itself is more durable than the pin.

 If you are thinking about having one or get some extra pins for backup, you can check below link to get one.

3D Touch Leveling Sensor & Probe: https://kingroon.com/products/3d-bltouch-leveling-sensor

Keep away from the magnet

 Magnets will change the magnetic poles of the 3D Touch, you need to keep it away from any magnets or anything that is magnetic. This issue is not easy to tell when use the 3D Touch with Marlin models.

 It was found during the initial setup in Klipper firmware. I was using the pin down and pin up command to test the 3D Touch on the KP3S 3D Printer. It works, but with opposite direction, but the configuration was all right. Then I remember that I put that pin on the refrigerator with a magnet. After replacing the pin, it works.

Use the same print as the tutorial do

This issue happens when using a different print to mount the 3D Touch. Because the coordinates of the detect points are defined in the marlin firmware, so using the same print to amount the 3D Touch makes sure those coordinates are detected correctly. If you prefer to use a different print, then you need to adjust the coordinates in the firmware configuration.

Use glue stick

The well stick initial layer is the key for every successful print, it is also important for a 3D Touch/BL Touch, because the fallen prints might damage the pin and ruin your hotend. So use glue stick on the heatbed will help to avoid such issue.

Preheat before Z Probe Offset

Some cold filament may stick on the nozzle and make your Z Probe Offset become not accurate. Preheating the nozzle will help to clean the nozzle and get you an accurate result. This tip also works for manual bed leveling.

Manual bed leveling first

 Manual bed leveling before upgrade to 3D Touch/BL Touch. It helps you make the bed as flat as possible. So, you can get much better result when using the new sensor.

No vibration

Make sure the desk is not vibrating when doing the auto bed leveling process, or it may fail or get you the wrong results. Turn off or pause the Klipper models near it of put the printer to a flat and stable desk to run the process.