I have the following hardware configuration:
- Ender 3 Pro
- SKR E3 Turbo
- Ender Extender 400XL
- BTT TFT35 E3 v3.0 (Marlin/LCD and BTT/BLTouch configured)
- Dual Z steppers (per Teaching Tech, example 3)
- Dual linear rails on Y-axis (adapters by printermods.com)
I plead guilty to having too many mods on this machine but everything was working until very recently.
After installing the linear rails mod, I discovered that the Y-axis movement was inverted in Marlin. I fixed that but (as of now) I can't get the device to home using sensorless homing (in Marlin mode on the TFT35) using Motion ▶ Auto Home. The gantry moves toward the (now disconnected) X-axis endstop switch (far left) and keeps buzzing until I press reset on TFT35 or cycle the power. The Y-axis seems close to appropriate. Marlin shows sensorless homing enabled/defined for the X and Y axes and the appropriate Diag pins are jumpered for the X and Y TMC2209s.
Additionally, the Z-axis seems to "think" the nozzle should be some 45 mm above the bed. This being so far off, the BLTouch doesn't ever get triggered so as to define a soft endstop.
Specifically, executing a
G28 Z results in an X and then Y gantry excursion to the apparent soft endstops, then to apparent X, Y - 0,0, then centering at X, Y - 200,200 (my bed is 400 x 400 mm). The nozzle then raises to an indicated 0 (i.e., 200, 200, 0) which is approximately 40.1 mm above the bed.
At my age, I know I am at wit's end when I voluntarily go out and mow several acres of lawn in the oppressive Georgia August heat.
Sorry for the long, rambling soliloquy. I would greatly appreciate any insight or other assistance anyone might offer.