Z homing SKR Pro1.2 Lowrider2

Hi,I just made a Lowrider2 with the SKR Pro1.2 Kit.

I tested the firmware SkrPro_DualLR_2209-2.0.7.2 and everything works perfectly but i would like to change the z-home direction to downwards.
When I tested the firmware with z-home to topwards (#define Z_HOME_DIR 1) my z-endstops work perfectly when i trigged them manually , but when i change the code (#define Z_HOME_DIR -1) my z-endstops didn’t work even if i triggered them manually.

Someone knows if I need to change something else?

Thanks for the support.

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First off, the LowRider firmware is configured to use G38.2 to probe downward, so you may just need to use G38 instead of the G28 homing command. If you really want to modify the firmware so that G28 homes downwards, here is a compare of the configuration.h file of the MPCNC Dual version (which homes downward) and the LowRider Dual version. Lines in blue are different.

You might have better luck starting with the dual version (non lr) and turning off dual X and turning on dual Z (and seeing Z2 endstop to xmax). That is all in configuration adv.

Just so you know, the reason we home up on the LR is because the gantry drops when it loses power and we don’t want to smash the endstops with the weight of the gantry. As a bonus, we can also use a probe after the axis is square.

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I tried downwards using G38 and still didn’t work but i changed the firmware like Jeff said and your images helped me a lot, now LR2 works like I want.
Thank you for the support.

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Hey Jeffeb3, I change the code like you said and it worked, now I can square it like I want to.

Thank you so much for the support.

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Hello, this is my first post, and I am a total beginner,…
I had the same problem, and I am trying to fix it with your solution @jeffeb3 doing this:

//#define X_DUAL_STEPPER_DRIVERS

//#define X_DUAL_ENDSTOPS

#define NUM_Z_STEPPER_DRIVERS 2
#if NUM_Z_STEPPER_DRIVERS > 1
#define Z_MULTI_ENDSTOPS
#if ENABLED(Z_MULTI_ENDSTOPS)
#define Z2_USE_ENDSTOP XMAX
#define Z2_ENDSTOP_ADJUSTMENT 0

But I have no luck, now does everything as should, but when I home Z, the Z axis move down even when the endstops are triggered, I have to reset to stop it. The end stops works fine tested with M119.
Very frustrating!!!

Any clue why is not working for me? Thanks in advance!!!

Dual endstops on LR are an advanced feature. You really can get by without endstops in all cases, and with a huge gantry like this, you should be able to get it very square before starting the motors, and they will stay square after they are powered.

If it is frustrating, I suggest you just take a step back, and use the machine without endstops. I know that may not be what you want to hear, but getting this stuff to work is partially academic, and doesn’t really have an impact in the output of the work from the machine.

If you really want dual endstops and a low rider, then it will be a lot frustrating if you stay closer to the beaten path and just home up, but probe down, which is how the DualLR firmware is set up. That firmware is still not tested by Ryan, but it is based off of some work from forum users that use it all the time (not myself, I just translated it). But it is more turn key than trying to configure it yourself.

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Ok, I’ll follow your advice and I’ll take an step back for now. But I will be back with a bit of more experience!! Thanks @jeffeb3

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