A face milling custom macro

Suggested by Glenn J. Doutrich Sr. of Inside Development Systems, Inc.

I’ve had several requests recently for this custom macro – so, here it is! This custom macro performs a face milling operation and allows the percentage of overlap to be specified. It provides for two methods of milling, climb milling (assuming a right hand cutter is used) and zig-zag milling in both directions.

The letter address M specifies which type of milling will be done. Leaving M out of the G65 command – or setting it to M1.0 will cause the machine to climb mill. Setting M to M2.0 will cause the machine to zig-zag mill back and forth until the milling is complete. This custom macro assumes the X length of the workpiece is longer than the Y length. That is, it makes passes along the X axis only.

The illustration shows the variable meanings:

Here is an example calling program followed by the custom macro.

• O0001 (EXAMPLE MAIN PROGRAM)

• N005 T01 M06 (4" FACE MILL)

• N010 G54 G90 S500 M03

• N015 G00 X0 Y0

• N020 G43 H01 Z2.0

• N025 G65 P1000 X0 Y0 Z0 C0.15 M2.0 U40.0 V33.0 D4.0 Q20.0 F15.0

• N030 G91 G28 Z0 M19

• N035 M30

Line N025 calls the face milling custom macro. X and Y specify the lower left corner. Z specifies the surface to be milled. C specifies the amount of clearance for the cutter (approach and escape distance). U and W specify the length and width of the part to be milled. D specifies the cutter diameter. Q specifies the overlap percentage (percentage of cutter diameter for overlap). F specifies the feedrate.

• O1000 (FACE MILLING CUSTOM MACRO)

• #120 = #7*[[100-#17]*.01] (effective cutter size)

• #121 = [2*[#7-#120]] + #22 (TOTAL STOCK INCLUDING OVERLAP)

• #100 = 1 (CURRENT PASS [COUNTER])

• #101 = FUP[#121/#120] (NUMBER OF PASSES)

• #102 = #25+#22+[#7-#120]-#7/2 (CURRENT Y)

• #103 = [#121-#7] / [#101-1] (Y STEP AMOUNT)

• #104 = #102-#103 (TESTER FOR "ZAG MOTION)

• IF[#13 EQ 2.0]GOTO 20 (TEST IF ZIG-ZAG)

• (CLIMB MILLING)

• N1 IF[#100 GT #101] GOTO 99

• G00 X[#24-#3-#7/2] Y#102

• Z#26

• G01 X[#24+#21+#3+#7/2] F#9

• G00 Z[#26+1.0]

• #100 = #100 +1 (STEP COUNTER)

• #102 = #102 -#103 (STEP CURRENT Y POSITION)

• GOTO 1 (GO BACK TO TEST)

• (ZIG-ZAG MILLING)

• N20 IF[#100 GT #101] GOTO 99

• G90 G00 X[#24-#3-#7/2] Y#102

• Z#26

• G01 X[#24+#21+#3+#7/2] F#9

• IF[[#25-[#7-#120]+#7/2]-0.02 GT #104] GOTO 25 (TEST IF ZAG PASS IS NEEDED)

• G00 G91 Y-#103

• G90 G01 X[#24-#3-#7/2]

• N25 #100 = #100 + 2 (STEP COUNTER)

• #102 = #102 -#103*2 (STEP CURRENT Y POSITION)

• #104 = #102-#103 (TESTER FOR "ZAG" MOTION)

• GOTO 20 (GO BACK TO TEST)

• N99 G00 Z[#26+1.0]

• M99