BLTouch vs. Other Sensors
※ 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.
■ 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.
■ Inductive Proximity Sensor
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?
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.
■ Solenoid Probe
Due to the built-in spring, it is necessary to apply a large current to the solenoid for a long time until probing is completed, so fatal problems such as heat generation and fire may occur. Hall sensor cannot be used because of the strong magnetic field of the solenoid.
Unlike general solenoids, BLTouch does not have a spring inside. Instead, a ferromagnetic core(hexagon wrench bolt) is provided at the top of the solenoid and a permanent magnet is provided at the top of the probe pin so that it can be deployed or stowed according to the current direction of the solenoid.
For the BLTouch solenoid current conduction time, the time necessary for the detection pin to reach the desired deploy or stow position, that is, about 100ms, is sufficient, and no current is required to maintain the position of the detection pin thereafter.
As soon as the probe pin reaches the stow position by the solenoid current, the permanent magnet at the top of the probe pin is attached to the ferromagnetic core (hexagonal wrench bolt), and the position of the probe pin is maintained without additional current.
In addition, after the probe pin reaches the deploy position by the solenoid current, the probe pin is maintained without additional current by its own weight.
Since there is no spring inside the solenoid, BLTouch is a very simple, safe and innovative product that can achieve its purpose with very little current and short control time, unlike general solenoids when deploying or stowing a detection pin.
Therefore, BLTouch must be installed perpendicular to the ground.
If BLTouch push-pin can't be perpendicular to the ground, BLTouch will put wrong signal out.