Sapphire Plus 3D printer upgrade : Installing a BLTouch sensor

If you think that manual leveling your bed is a real pain each time you start printing (and particularly if you have a removeable magnetic print bed), then adding a BLTouch sensor will likely save you a ton of times and freedom of mind.

Here's a tutorial about how to do it for the Sapphire Plus printer.

This video is useful to understand what we'll do:

Step 1: Printing a BLTouch support

This depends on the hotend you have installed. It can be as simple as this: BLTouch mount by TwoTrees

Or, if you have updated your printer to use a E3D hotend, you'll find the piece to print in PETG here.

Step 2: Wiring the BLTouch

Sapphire Plus connection holes are kind of stupid. The mainboard is in front of you, yet they've preferred to dig a hole at the back of the printer so that wire need to go to the back then to the front in the bottom chassis. In the end, the required wire's length is too long to fit the provided wire extension in the delivered BLTouch sensor so you need to cut and add something like one meter of additional cable. Not sure it's good for the signal, so I've twisted these wires hopefully making them less prone to noise.

In my case, I'm keeping the Z-Min endstop sensor, so I'm plugging the BLTouch to the Z-Max endstop sensor, following this wiring: BLTouch MKS Robin Nano V1.2 wiring

Beware about the mistake I made initially: the other endstop are simple switch, so they are plugged with the black wire on the left so you might think that the ground pin is on the left of the connector: It's not!


So, when I plugged mine this way, I made a mistake:

Wrong connection for BLTouch

The black wire should be the center pin (so it should have read: White Black, and not Black White).

Step 3: Hardware check

Ok, now you've wired the sensor correctly, you need to test it. Without powering the printer up, and with a multimeter, ensure you've a connection between the GND of the mainboard and the two G pin on the BLTouch. Then power on the printer and ensure you have 5V on the 5V pin of the BLTouch.

If it does not show the expected tension, power off and double check the connections.

Step 4: Software part

This part is the most complex in the installation, you'll need to rebuild a Marlin's firmware for your printer by including the BLTouch in the configuration. I'm describing how to build a new firmware here.

I'm preparing a pre-build version I'll post here soon.

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