Tutorial of Adding BLTouch on Anet A8 3D Printer

how to install a 3d touch bed leveling probe on your Anet A8 3D printer.
hardware installation and wiring
firmware calculation and sensor calibration

Automatic Bed Leveling with BL Touch

Automatic bed leveling is an important step before starting to print on a 3D printer to get the information about little height differences between the edges and the center of the bed . The printer firmware takes this information to calculate movements of the z-axis to compensate for these little inequalities to some extent.
3D Touch probe is made by a company called Geeta. There is a similar but more expensive probe on the market called the BLtouch which has the same functionality and wiring.

BLTouch Sensor VS Capacitive Leveling Sensor

What makes the 3d Touch or BLTouch senser different than a capacitive or inductive leveling sensor is that it is a combination of a whole sensor and the server. The server pushes out a little pin. and if the pin hits the bed while the set access is being lowered, the whole sensor detects that and delivers a signal to the printer so it can calculate the distance.

3D Touch Probe Wiring

3D touch sensor has five wires. The brown and the black wires are ground cables so we can put them together. Ground to red and the white cable will be connected to the Z axis connector on your Anet A8 motherboard. 
anet a8 bltoch
The orange cable needs to be connected to the third wire off the display cable or to the seventh wire. If you use an A6 or display of an a6 on the Anet A8. This means we would have to cut that wire and pull it aside of the other nine cameras of the flatbed cable so you can connect the probes control signal to it.
anet a8 bltouch sensor
However I like to avoid having to cut the original disciplic cable and also want a solution that's plug-and-play.
We'll build an adpater that will allow us to install the sensor to the board very easily. Let's check out the list of parts that we will need to build the adapter to do Poe or several extension cables.

Hardware List (Besides the 3DTouch Probe)

· 2 x Dupont (Servo) extension cables

· 1 x 3-pin JST connector and pins

· 3 x wires for JST connector

· 1 x display extension cable

· 5 x header pins: a 3 pin header and one male of two pin header

· Piece of stripboard with 4 rows


. a piece of strip board with four rows. assembling all this gives us

3d touch / bltouch adapter schema image:
anet a8 bltouch
Once having assembled the adapter, we can just plug in the adapter cable in
between the display cable and the mainboard and connect our sensor extension cables to it.
The next step is to mount the sensor to the print head which is done by using
a printed holder part.
Thingiverse link: https://www.thingiverse.com/thing:2331878
It's going to be mounted between the filament cooler fan and the extruder cooling block. Don't forget to remove the old set and the limit switch.
Next article How to Fix Burned Hotbed Connector on Anet A8 3D Printer

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