QTPlasmaC, first cut ever. What to do after "initial setup"?

This would be a easy one for you guys, I just lost 2 days trying to make it work.

I have set Z axis like this:
 

I have this PARAMETERS tab:
 

Initial setup (probe-test) runs ok. My torch sits 3 mm above material.
Documentation says: "CONGRATULATIONS! you should now have a working QtPlasmaC Configuration."

At this point, I loaded GCODE file metric_wrench.ngc and set G54 for X and Y, screen looks like this:
 

When I CICLE_START, I got the error:  "pierce height would exceed Z axis maximum safe height, condition found while float switch probing"
I have made a video:
 

I am sure, as a newbie, I am missing something.  Could not find directions (looking at docs)  of the correct workflow after initial setup.

I don't understand how pierce height (which is 3 mm) would  exceed safe height which is 20mm , if both are measured from the same level.

Safe height can be set from 1 to 74, and I tried lots of values without success.

Thanks,

 

I see Z-74 the zero must be made at the lowest point that the torch reaches by pressing the zero next to the dro z .. at least I did so after having troubled a few hours.
since it uses g53 you have to do home for that too

I have followed "initial setup" instructions where it tells to take Z to minimum (-74) and touch-off.

You can see in the pic that my home position is 69 at G54 ( which is -5 in G53) so that when torch is at G54 Z0 it is at G53 Z-74

I can't explain myself well with the translator but the negative number is not good. I have always used g54, but since the example file uses g53 repeat touch off as for g 54

 the safe height is set to low at 22mm in the parameters tab.
With the 8mm difference and over run and float travel you have near to that value, so just change that to something bigger.

I have set safe height bigger, like 50 or 74, and even lower like 5 or 1. Could no get rid of the error.
That's why I have posted here, I thought I was doing something wrong. 

What just crossed my mind is that I should try to tighten all the values: less switch travel, less min-Z, less overrun and mess again with safe height.

Any thoughts ?

I don't know if this is "by design", but the exact moment the float-switch trips the DRO shows Z like it was in G53 (-67).

This may be nothing, but it might be worth mention it.

0:09 in the video:

 

Of course, Phill, thanks for looking at it.