Problems with homing direction with sensorless homing
Hey there.
I'm currently building my self sourced vCore (300) with an Octopus Pro 446 and TMC2209 drivers and struggle with homing directions with sensorless homing. I face an issue where my jog direction and homing directions seems to be opposite all of the time. Jogging x to the left works, but then my x axis is homing to the right (max) direction. The same with the y axis. I switched stepper cables in every possible configuration I think. Whats weird for me is the opposite movement at jogging / homing. Also the homing itself isn't working as I can still jog into the x max position after homing x. Also I only have 150mm travel after homing -> I can move the carriage to the approx center of the x axis then but not further.
All files in RatOS are untouched (verified by
git status). My only overrides are in the section in the printer config. I copied the sensorless config to the config directory and made the changes for the includes in the printer.cfg (removed physical - added sensorless).
I'm clueless where I messed up or what part is missing for me. Maybe you can spot my issue?
Please ignore the other settings in the printer config. I have no heaters attached yet and wanted to ignore the z-hop on homing for now. Also I'm using a low current for the steppers till I have calibrated them (z and xy steppers are different kinds and not the steppers from the bom). I think the lower currents have to be adjusted when tuning the sensivity but inverted directions should not have any to do with low currents I believe.
Thank you very much!
4 Replies
Sounds like you just haven't tuned your sensorless homing properly. (Support issues like these are why i don't recommend sensorless homing). It's triggering instantly thus giving you the impression it's homing in the wrong direction (that is in fact centering the axis after that axis has been homed).
It's also possible you forgot to insert the diag jumpers for the X and Y drivers.
Aah yeah, looking at the pic of your board you did indeed forget the diag jumpers.
Sensorless homing doesn't work without those.
Refer to the Octopus Pro manual
provincial-silver•13mo ago
Now that all makes sense then. So I didn’t see a homing move but an immediate travel to the center. Maybe setting the jumpers might be missing in the documentation? I did not see a info about this or I maybe I was not reading carefully.
Thank you very much, I will answer again when I have time to check.
I think sensorless homing for xy is great as it reduces hardware and wiring, but as you said is harder to debug for the average user. Maybe if it is the same issues it might be worthy to extend the documentation with the regular pitfalls?
What documentation? There's no rat rig provided documentation for sensorless homing, as both Rat Rig and RatOS wants you to use endstops.
It's harder to set up, it's less reliable, less accurate and more taxing on the hardware.
IT's generally just worse than endstops. Not really a worthy compromise for saving 2 x 3-pin wires, especially since you can order them off the shelf.
provincial-silver•13mo ago
My bad, I mixed documentations - sorry. There is no info about it in the RatOS docs.
All your points are valid.
In my opinion accuracy is negligible on X and Y and only necessary if you want to use the whole print sheet - which I never did till now. I would have bought the TMC2209 in any case and with wiring I had issues with long cables for the endstops on my Hypercube. And once tuned I never had reliabillity issues with sensorless homing on my Hypercube. But for the masses I admit, physical endstops are more common and suitable.
And everything working as intended now. Seems the Jumpers were my only missing part. Thank you very much for pointing me into the right direction :)!