I am confused about installing BLTouch on CR-10S.

This is my motherboard:

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Below is a screenshot for the wiring of the BLTouch sensor:

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See the circled sections in yellow.

Notice that the Z- socket is also used (black and white BLTouch wire) and that's normally where the endstop limit switch sensor is plugged in.

If I unplug the limit switch wire and simply plug the BLTouch wire to this:

1. How can the printer determine when it has reached home?

2. How does it know when to stop when it hits home?

3. I thought BLTouch is used to do some leveling on the surface... Does BLTouch have a sensor to stop the printer when it hits some?

4. Any way to install BLTouch without removing the Z limit switch sensor?

Sorry for the questions. I am just confused about BLTouch using pins of another sensor that's also required.


1 Answer 1


A touch sensor is also a height limiting switch, so you sacrifice the Z- limit switch in favor of the touch sensor (or an inductive sensor). Furthermore, all your concerns are taken care of by the firmware. You configure the firmware so that the nozzle homes Z in the center of the build plate after X and Y are homed first.

It is advised to look up some videos of working touch sensors, then you will get an idea what actually happens. You could start with the inventor of the sensor.

  • $\begingroup$ Ok that really make sense. I also confused Z+- axis with Y-axis because I use Maya which has different ordinate in a way that Y+- is up/down and Z+- is front/back while X+- is right/left. I forget it's different in 3D printing. $\endgroup$
    – Programmer
    Nov 22, 2018 at 0:27

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