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Question RPM Monitoring and Auto Z Issues


New member
Hello Everyone!

I'm early into my Voron journey and I have it hit a couple of challenges that I could use some help with.

For reference:
Voron 2.4R2
Fystec Spider 2.2
fluidd v1.29.0
klipper v0.12.0-125-gbfb71bc2
moonraker v0.8.0-324-ga3e4dac5

#1 - Hotend fan RPM Monitoring
I was following the Ellis Print Tuning Guide and decided that the RPM monitoring for the hotend fan was a great idea so I bought the recommended Orion OD4010-24HB01A fan. It's been installed and wired in, the fan itself seems to be working fine PWM fan speed an all. However, I can't seem to get the RPM to report at all. I added the relivant code to the printer.cfg, referenced the fan_tach_monitor.cfg file and added that file to the printer. I have no errors.

I also added a little bit of debug code to fan_tach_monitor.cfg so I could verify that parameters are being passed properly.
M118 RPM = {rpm}
M118 Target = {he_target}
M118 Temp = {he_temp}

The output - fan is running at this point.

I also borrowed an oscilloscope from work to check and see if I could verify the pulses on the tach wire. I don't see the square wave like I think I should be seeing, but I do see a change as the RPM increases or decreases. The amplitude of what I see gets larger with higher RPM and vice versa. I'm not great with oscilloscopes, mostly fumbling my way around them, so take this info with a grain of salt.

Hotend config:
[heater_fan hotend_fan]

## Select pin for your Spider board
pin: PA14 # Spider 2.2
max_power: 1.0
#kick_start_time: 0.5
heater: extruder
heater_temp: 50.0
tachometer_pin: ^PB14
tachometer_ppr: 2
tachometer_poll_interval: 0.0015

#2 - Auto Z Calibration
I'm using the code from Protoloft - Klipper Z Calibration with a klicky probe and up until my last round of updates this was working fine. But I ran the system updates and now I get the following error
Section 'z_calibration' is not a valid config section
I have looked through the code, wiki, and git. I'm not sure what has changed that requires updating in my z_calibration section. (I have this in a separate file and it is called in the printer config)
nozzle_xy_position: 205, 309
switch_xy_position: 200, 289
bed_xy_position: 150, 150
switch_offset: 0.33
offset_margins: -1.0,1.0
samples: 3
samples_tolerance: 0.01
samples_tolerance_retries: 3
samples_result: median
safe_z_height: 12.84
position_min: -5
speed: 50
lift_speed: 50
probing_speed: 8
probing_second_speed: 3
probing_retract_dist: 3
probing_first_fast: false
start_gcode: Attach_Probe
end_gcode: Dock_Probe

Thanks for any help!


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Fiddling with the printer tonight, I was able to fix my issue with the Auto Z Calibration. It seems that one of the updates either uninstalled or broke the reference to z_calibration.py
The fix was to SSH into the printer and run ./klipper_z_calibration/install.sh to reinstall the package.

I know protoloft has an auto updater built in that can be installed. It was still showing that z_calibration was up to date.

1 problem down and 1 to go.