Lowrider - SKR 1.3, Dual Y and Z, TMC2209 UART, Sensorless Homing

It should. You just have to roll up your sleeves and configure it. The drivers are the same, and the processor and stuff shouldn’t be different enough to matter.

I’ve found this very helpful. My goal is to do what KCGreg has done with senseless homing. I have an SKR 2 instead of the 1.3, does that change anything in the firmware? I currently have dual y and dual z motors connected in serial mode. Do I need to run them individually and use my E0 and E1drivers? Looking forward to implementing this along with the TFT touch screen.

just a question about sensorless homing, i use your firmware and z axis sensorless homing not working. i have same skr 1.3 and tmc2209, z axis alway home issues, do you know how to fix it?

There are no hard stops on the Z axis on a stock build so sensorless homing will destroy your couplers.

i just tap a m5 screw and use as a endstop because i can adjus the sensitive, the only problem i have is z axis, somehow i cant get it to work

For sensorless homing, the motors need to skip. They will destroy the couplers before they skip. Regular endstops can be used with Z and a screw for adjustment. Sensorless homing isn’t a good idea here.

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Not really, with bump homing disabled on Z (a must for sensorless mode) and sensitivity set right, the motor will not lose a step. If it does then the accuracy of homing is greatly diminished.

The challenge of-course is that every motor is different so you will skip some steps while tuning the values :slight_smile:

Destroying the couplers is only ever an issue when homing to Z- or DOWN. Homing up will not stretch the couplers but requires extra hardware to block the movement. With default setup there is really nothing that would stop the lead screw threading itself out of the nut or worse.

I don’t have a good solution here. On one hand homing in Z- direction with “coupler savers” is great because both sides are guaranteed to end up at the same height from the wheels by the virtue of mechanical design. However the savers may also break and it’s really annyoing if you lose position and then have to re-home when you have a bit mounted and some thick material attached to the bed.

I’d probably opt for hard stops clamped around Z pipes and homing towards Z+ as a recommendation. Now if only one could find a good way to calibrate / set these stops so both sides end up being equal :stuck_out_tongue:

How exactly does one disable bump homing on Z?

…And I’m still reading/trying to learn how to get sensitivity set right.

Re: configuration_adv.h

As per KCGreg’s notes, set the following to sensitivity of 20:

#define X_STALL_SENSITIVITY 20 // Stall sensitivity must be > 0
#define Y_STALL_SENSITIVITY 20 // Stall sensitivity must be > 0
#define Z_STALL_SENSITIVITY 20 // Stall sensitivity must be > 0

As of today’s date, when I downloaded the Bugfix edition of Marlin, the following was commented out, but to me it makes sense to uncomment it.

//#define Z2_STALL_SENSITIVITY Z_STALL_SENSITIVITY

So…

#define Z2_STALL_SENSITIVITY Z_STALL_SENSITIVITY

Does this sound right?

There is a Z_HOME_BUMP_MM or something. You just set it to zero.

Thanks! OK, I found this:

#define HOMING_BUMP_MM { 5, 5, 2 }

I am assuming the three numbers are the X, Y, and Z settings, so the third one.

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@ KCGreg

Hey, I’ve used your notes to configure sensorless homing, and I got a successful build, based on editing the V1 firmware for dual endstops. I changed that file according to your notes. However, while homing works, it only homes to one of the two Z steppers and only homes to one of the two Y steppers. So, when I try to test it fixing being out of square, it fails that test. Any idea what I may be missing?

UPDATE: SUCCESS. After a lot of work tweaking config files and compiling firmware, I finally got Sensorless Dual Homing working for both Y and Z on my LowRider v2 with SKR Pro 1.2 and TMC2209 drivers! :slight_smile:

I feel like I became a junior expert on this. LOL.

Details on my efforts (and a download of my build files, configs, etc) are available here: Doug Joseph (Design8Studio) Full-Sheet LowRider 2 "Build on a Budget" - #11 by DougJoseph

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