My profuse apologies for:

my (very) late answer digging up this old topic (Halloween trick or treat ?!)

but my answer is still relevant (based on the code base of the RRF 3.5.0 rc1 and 3.4.6).

@dc42 said in G30: unexpected probe dive motion range:

If you set the dive height to some value H [...] the code starts the dive at (trigger_height + H) and ends it if the probe is not triggered first at (trigger_height - H)

That is my expectation, but not what the G30 command currently does.

You will notice in the code of G30 command the mention of platform.AxisMinimum(Z_AXIS), variable which I can't make sense of:

ms.coords[Z_AXIS] = (IsAxisHomed(Z_AXIS)) ? platform.AxisMinimum(Z_AXIS) - zp->GetDiveHeight() + zp->GetActualTriggerHeight()

This is in contrast to the probing code of the G29 command, which works as you described without ever using platform.AxisMinimum(Z_AXIS):

ms.coords[Z_AXIS] = -zp->GetDiveHeight() + zp->GetActualTriggerHeight();

Hence my (old yet still relevant) pull request.

Hopefully this patch would not bring any regression, however it might save multiple RRF user from less than desirable unexpected nozzle crashes.

Apply external triggers with 'meaningful' names