BLTouch Auto Bed Leveling Sensor for 3D Printers v3.1

Summary 

BLTouch is an auto leveling sensor for 3D Printers that can precisely measure the tilt of Bed surface. It could work with any kinds of bed materials, such as glasses, woods, metals, and so on.

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Features 

Main functions and controls of BLTouch are the same as usual auto bed leveling sensor, consists of RC servo and micro switch. Thus, BLTouch can be applied on almost every board.

BLTouch is fulfilled with simple structure and high precision by using progressively designed solenoid and hall sensor. It aims for user convenience and enjoyable printing by adding many smart functions, such as self-test, alarm, alarm release & Touch Switch mode, Blue LED for servo signal indicating and Z-probe(Zmin) Testing.

Simple

BLTouch can be easily applied, since it has a small and simple structure. As BLTouch works as usual auto bed leveling sensor, Gathering information & setting up your firmware will be an easy task.

Smart

Self-test : The push pin operate two times in a test when the power is on.

Alarm : The LED light blinks if a problem was found on a self-test or during operation.

High-precision

BLTouch’s Standard Deviation in repeatability is around 0.005mm, at that precise.

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BLTouch vs. other sensor

The Latest Version

As you can see in the picture, the push-pin of the genuine BLTouch is very sophisticated by the CNC equipment.

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Specification

Wiring

BLTouch can be operated in the following condition.

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One I/O for control (Orange wire : PWM or Software PWM)

One I/O for Zmin(White wire : endstop / Z-probe)

GND and +5V power

Most Board provides its own servo pin, so BLTouch can be used connected to one of those servo pins. As each servo pin has its own number, BLTouch will be controled with the servo pin number as following.

(Soldering and firmware update might be needed in rare case)

M280 P0 S90 ← SERVO0_PIN

M280 P1 S90 ← SERVO1_PIN

M280 P2 S90 ← SERVO2_PIN

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e.g. RAMPS1.4 Wiring

Servo signal(orange wire) : D11 (SERVO0),     Zmin (white wire) : D18 (Zmin endstop)

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If you need, you can rearrange the position of cables by tweezers or cutter like in the picture.

■ Micro switch

BLTouch is equipped with all three function as micro switch, servo motor and also servo arm.

Comparison would be pointless if micro switch sensor for bed leveling does not include the retraction and deployment method.

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■ Inductive Proximity Sensor

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At Inductive Proximity Sensors, to calculate the sensing distance for other application conditions the following parameters, which affect the sensing distance, must be taken into account. (For example : Variations in ambient temperature(Kθ), Different types of object material(Km), Size of the object to be detected(Kd), Variation of supply voltage(Kt))  

Sa(assured sensing distance) = Sn x Kθ x Km x Kd x KtSn : nominal sensing distanceIf non-contacting Inductive Proximity sensor can be provided the same Parameter at whole working area, it must be the best auto bed leveling sensor for 3D printers.

But who can provide this?

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Most of metal beds have various temperature(Kθ) areas at one bed, and its thickness(Kd) and object material(Km) are also various because of bolts, nuts, or supporters etc.

※ The data above can be varied by assembling shape and other environments

But assembled with the low quality 3D printer, we just get the value as 0.001~0.05mm. (It was the same BLTouch) Actually, around 0.05 is also not much problem at FDM type 3D printers.

■ BLTouch

BLTouch must be installed perpendicular to the ground.

If BLTouch push-pin can't be perpendicular to the ground, BLTouch will out put wrong signal.