ABL and accuracy, which probe to choose?

General Discussion
16

Just did it on one of my printers. Custom CoreXY cold with a TriangleLab probe:

2:49 PM
probe accuracy results: maximum 0.729932, minimum 0.727435, range 0.002497, average 0.728185, median 0.728685, standard deviation 0.001500

This is pretty standard for what I’ve been seeing with the 8mm inductive probes.

Sorry, I don’t have any of the 12mm or Omron TL-Q5MC2-Z probes set up right now.

There are no internal pull ups on the 8mm inductive probes I’m using so there is no danger of overloading a pin.

Regardless, I just looked at the schematics for the EBB42 I’m connecting the inductive probe to and when I look at the Endstop socket, I see:

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There’s a voltage divider which provides a current limiting resistor as a measure of protection for the STM32 pin in an overvoltage situation.

There is similar protection on the BLtouch “PROBE” pin:

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Just out of curiosity, I took a look around and:

  1. The Manta M8P has a similar BL Touch circuit as the EBB42 with the current limiting resistor going to 3.3V on PROBE. They do NOT have the 5 pin endstop connector of the EBB42.
  2. The Octopus and Octopus Pro do NOT have the current limiting resistor going to 3.3V on PROBE. They do NOT have the 5 pin endstop connector of the EBB42.

I could look around at other boards, but these are the ones that I have schematics for at hand. This is probably something to consider when selecting a main controller board if you expect to use a BL Touch.

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