[safe_z_home] Override z_endstops

Basic Information:

Printer Model: voron0.2
MCU / Printerboard:SKR mini E3 v2

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Describe your issue:

z_ hop can’t verify that the hop moves towards the negative value, but the Z zero of voron0.2 and the limit switch are at the maximum value of Z, that is, the bottom. This results in if the platform is at the bottom, and if z is configuredz_hop is 5, and then execute the G28 X0Y0 or G28. Even if Z has triggered the limit switch, z will continue to increase and move downward by 5mm, which will cause Z to exceed the travel and hit the frame.
z_hop向负值方向移动我无法验证,但是voron0.2 的Z归零和限位开关在Z的最大值,也就是最底部。 这样造成如果平台处于最底部,如果配置z_hop为5,然后执行归零XY或者全部归零,即使Z已经触发限位开关,但是z还会继续增加向下移动5mm,也就导致Z会超出行程,撞上框架。

This might help: Moving Z before homing or other

It is because Z is moved before zero and Z is near the maximum value. So continue to move to trigger the limit, or continue to move…

For example, when z is at 148 and the maximum value of Z is 150, Z first_ Hop 5 means that Z has obviously exceeded the maximum value of 150 to change from 148 to 153. Even if the limit switch is triggered, it will still move.
就是因为归零前移动Z 而Z处于接近最大值。 所以继续移动触发限位,还是接着移动。。。
比如:z处于148 ,Z最大值150 归零时首先Z_hop 5 意味着Z要从148变成153 显然已经超出150的最大值,即使触发限位开关,还会照样移动。

I see three potential solutions for your issue:

  1. Do not use z_hop
  2. Use [homing_override] and some macro as detailed in the link above to move upwards before actually homing. This of course shifts your issue to Z=0
  3. Establish a “custom homing”, e.g. HOME_LOW, which you call instead of the regular G28 in case your Z is close to maximum