(corner plate X/Y/Z zeroing macro)
(start 18 from plate edges)
(4mm plate, 4.6mm margin)
(5mm dia. probe w/ 5mm backoff = 7.5 offset)

(zero X/Y/Z)
Zero

(z touch off from up to 40 away)
Z-40 F120
(plate 4 + backoff 5)
Z=9

(x to left, 18 + 7.5 = 5 gap)
X-25.5 F2000
(z down, backoff 5 + 5)
Z-10 F1000
(x touch off from up to 10 away)
X10 F120
(offset 7.5 + margin 4.6)
X=-12.1

(y to front, 18 + 7.5)
Y-25.5 F2000
(x to 18 + 7.5)
X25.5
(touch off y)
Y10 F120
(set y)
Y=-12.1

(z up, backoff 5 + 5)
Z10 F2000
(goto X/Y 0)
XY