From dfe6d3f066c468da8f5f380a79dcc80924447349 Mon Sep 17 00:00:00 2001 From: Timofey Titovets Date: Wed, 7 Jan 2026 17:16:48 +0100 Subject: [PATCH] docs: describe calibration output Add a hint about the connection between the calibration output and tap threshold. Signed-off-by: Timofey Titovets --- docs/Eddy_Probe.md | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/docs/Eddy_Probe.md b/docs/Eddy_Probe.md index 58b3abb7f..d24aadf31 100644 --- a/docs/Eddy_Probe.md +++ b/docs/Eddy_Probe.md @@ -24,6 +24,7 @@ named `[probe_eddy_current my_eddy_probe]` then one would run complete in a few seconds. After it completes, issue a `SAVE_CONFIG` command to save the results to the printer.cfg and restart. +Eddy current is used as a proximity/distance sensor (similar to a laser ruler). The second step in calibration is to correlate the sensor readings to the corresponding Z heights. Home the printer and navigate the toolhead so that the nozzle is near the center of the bed. Then run a @@ -35,7 +36,17 @@ those steps are complete one can `ACCEPT` the position. The tool will then move the toolhead so that the sensor is above the point where the nozzle used to be and run a series of movements to correlate the sensor to Z positions. This will take a couple of minutes. After the -tool completes, issue a `SAVE_CONFIG` command to save the results to +tool completes it will output the sensor performance data: +``` +probe_eddy_current: noise 0.000642mm, MAD_Hz=11.314 in 2525 queries +Total frequency range: 45000.012 Hz +z_offset: 0.250 # noise 0.000200mm, MAD_Hz=11.000 +z_offset: 0.530 # noise 0.000300mm, MAD_Hz=12.000 +z_offset: 1.010 # noise 0.000400mm, MAD_Hz=14.000 +z_offset: 2.010 # noise 0.000600mm, MAD_Hz=12.000 +z_offset: 3.010 # noise 0.000700mm, MAD_Hz=9.000 +``` +issue a `SAVE_CONFIG` command to save the results to the printer.cfg and restart. After initial calibration it is a good idea to verify that the @@ -112,6 +123,19 @@ is too close to the bed before the tap. - Too low - can make the toolhead stop in mid-air because of the noise. +You can estimate the initial threshold value by analyzing your own +calibration routine output: +``` +probe_eddy_current: noise 0.000642mm, MAD_Hz=11.314 +... +z_offset: 1.010 # noise 0.000400mm, MAD_Hz=14.000 +``` +The estimation will be: +``` +MAD_Hz * 2 +11.314 * 2 = 22.628 +``` + You can validate the tap precision by measuring the paper thickness from the initial calibration guide. It is expected to be ~0.1mm.