So I’ll answer my own question in case it’s helpfull to some other CNC nube.
With the settings below I have (for my machine) both G28.2 and G38.2 commands working as they should. 🙂
“G28.2z0” homes to my upper/max switch.
Making no software setting changes, “g38.2 z-100 f1000” moves down to my alligator clip and touch plate (a Normally Open switch/sensor) that is connected to the TinyG Zmin and ground terminals.
settings for my machine:
(motor 4/Z, direct drive 1.8 degree, nema23, 2.8amp, 269 oz.in.)
$4ma=2 (map to axis, 0=X,1=Y,2=Z)
$4tr=2.540 (mm travel per revolution, 2.540)
(1/2 dia., 10 tpi ACME right-hand lead screw)
$4mi=4 (microsteps, 1,2,4,8)
$4po=1 (polarity, 0=normal,1=reverse)
$4pm=3 (power management)
(Z axis)
$ztm=95 (travel maximum)
$ztn=.000 (travel minimum)
$zvm=500.000 (velocity maximum, mm/min)
$zfr=500.000 (feedrate maximum, mm/min)
$zsv=200 (search velocity, mm/min)
$zlv=100 (latch velocity, mm/min)
$zlb=20 (latch backoff, mm)
$zzb=5 (zero backoff, mm)
