I had set the retract height set to 50mm and through that discovered an odd behavior.
It seems that when there is not enough travel on the Z axis, for example when the stock is high, the retract action causes the Shapeoko to lose the Z axis zero as it tries to Tavel beyond the limit of travel.
This has disastrous impact on the piece, needless to say.
The retract height is hard wired into the GRBL generated by CC, while CM has no mechanism for overwriting this.
So the only solution is to manually edit the NC file, or regenerate the GRBL.
My conclusion was to reduce the retract height significantly to 10mm, but I think a software fix is required.
The safety/retract height is set in Job Setup (gear icon) see:
Hi @ariel,
Yes, this is a lesson many of us have come to learn the hard way, you will find plenty of threads around this situation. The next question is usually “but why can’t the machine check that there is enough Z travel left to retract, or at least stop when it hits the limits switch”, and I don’t pretend I could provide a decent one line answer but this has been discussed at length in other threads (basically: it’s hard to predict because it depends on the machine setup, how high your wasteboard is, etc…and it’s not straightforward to stop upon detection either because it requires to activate limits detection during the job, which is prone to false detection that would infuriate people even more)
I’ve put in a suggestion that after any negative Z move Carbide Motion check the state of the Z-axis homing switch — probably if CM kept track of the heights moved to and only checked after the highest yet move there wouldn’t be much of a performance impact — @robgrz would that be workable?
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I believe that during the machine initialization step in Carbide Motion it is easily possible to calculate “available positive z travel from zero”, and likewise “maximum plunge depth”.
The caveat with MPD is that it may plunge through the washboard as the bit hight is an unknown, but APZTFZ is a no-brainer.
Using APZTFZ it is quite easy to avoid catastrophic travels in the Z positive direction.
MPD together with the BitSetter, can also solve the Z negative problem.
A lot of benefit with a few lines of code …
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