Block center finder Gcode

Here is the Gcode that makes it all happen:

(probe to find center and size of rectangular block)
(Reference XY coords of the probe at bot LH corner of block)
(This program will not run as given here. You have to)
(insert numbers in place of {description of number}.)

m5 (ensure spindle is not running)

;Set the monitor variables to zero
#1=0
#2=0
#3=0
#4=0

#5=180 (X-rh)
#6=0 (X-lh)
#7=200 (Y-top)
#8=0 (Y-bot)
#9=0 (good x-ctr)
#10=0 (good Y-ctr)
#17=0 (Z-ref)
#18=4 (edge clearances)

#11=[[#5-#6]/2] (nominal X-value of block center)
#12=[[#7-#8]/2] (nominal Y-value of block center)
#13=-3.5 (some Z-value below the block surface)
#14=3 (probe tip radius)

#15=[#5-#6] (nominal width X-dir)
#16=[#7-#8] (nominal height Y-dir)

;move to nominal block center
G0 X#11 Y#12 (move to nominal block center)
G31 Z-50 f50 (probe Z-ref)
G0 Z[#2002+2] (move above block)
#17=#2002

;probe +X side of block
g0 X[#11+#15/2+#14+#18] (move past +X-edge)
g0 Z[#13+#17] (descend below surface)
G31 X[#11 - #15] (probe +X side of block)
#5=[#2000-#14] (RH edge)
g0 Z[#17+2]

;move to nominal block center
G0 X#11 Y#12 (move to nominal block center)

;probe -X side of block
g0 X[#11-#15/2-#14-#18] (move past -X-edge)
g0 Z[#13+#17] (descend below surface)
G31 X[#11 + #15] (probe -X side of hole)
#6=[#2000+#14] (LH edge)
#9=[[#5 + #6] / 2.0] (good X-block center)
g0 z[#17+2]
#1=[#5-#6] (+RH edge + -LH edge - +tool dia = Xwidth)

;################################################

;move to nominal block center
G0 X#9 Y#12 (back to center of block)

;probe +Y side of block
g0 Y[#12+#16/2+#14+#18] (move past +Y-edge)
g0 Z[#13+#17] (descend below surface)
G31 Y[#12 - #16]
#7=[#2001-#14] (Top edge)
g0 Z[#17+2]

;move to nominal block center
G0 X#9 Y#12 (back to center of block)

;probe +Y side of block
g0 Y[#12-#16/2-#14-#18] (move past -Y-edge)
g0 Z[#13+#17] (descend below surface)
G31 Y[#12 + #16] (probe -Y side of block)
#8=[#2001+#14] (Bot edge)
#10=[[#7 + #8] / 2.0] (good Y-value block center)
g0 Z[#17+2]
#2=[#7-#8] (Top edge - Bot edge - tool dia = Yheight)

g0 x#9 y#10 (go to XYctr)
M30