I am using Mach 3 ver R3.042.029 on a Tormach PCNC1100. An example Thread

Mill Wizard from Mach3 is a 1-8 outside thread shown below for a single form

cutter.

G0 G49 G40 G17 G80 G50 G90

M6 T46 (TOOL DIA. 0.504)

G20 (Inch)

M03 S1000

G64

G00 G43 H46 Z0

(Right hand OD Climb)

X1.075 Y0.2875

G01 Z0.0625 F15

G01 G41 P0.25 X0.7875 F15

G03 X0.5 Y0 R0.2875

G02 X-0.5 Y0 R0.5 Z0

G02 X0.5 Y0 R0.5 Z-0.0625

G02 X-0.5 Y0 R0.5 Z-0.125

G02 X0.5 Y0 R0.5 Z-0.1875

G03 X0.7875 Y-0.2875 R0.2875

G01 G40 X1.075

G00 Z0

M5 M9

M30

I want to add a finish pass at the bottom of this outside thread where there

is no change in Z. This is to give the bolt part a smooth shoulder that a

nut (inside thread) can butt up against and not show any exposed threads on

the shaft of the bolt. See starred lines in G-code below.

G0 G49 G40 G17 G80 G50 G90

M6 T46 (TOOL DIA. 0.504)

G20 (Inch)

M03 S1000

G64

G00 G43 H46 Z0

(Right hand OD Climb)

X1.075 Y0.2875

G01 Z0.0625 F15

G01 G41 P0.25 X0.7875 F15

G03 X0.5 Y0 R0.2875

G02 X-0.5 Y0 R0.5 Z0

G02 X0.5 Y0 R0.5 Z-0.0625

G02 X-0.5 Y0 R0.5 Z-0.125

G02 X0.5 Y0 R0.5 Z-0.1875

G02 X-0.5 Y0 R0.5 Z-0.1875 * (this line added by me)

G02 X0.5 Y0 R0.5 Z-0.1875 * (this line added by me)

G03 X0.7875 Y-0.2875 R0.2875

G01 G40 X1.075

G00 Z0

M5 M9

M30

When I just add a circular (Z not changing) pass after the last helical pass

(Z dropping) using the exact same X,Y, and R parameters Mach 3 gives me an

error that the tool path is ending at the same point that the previous tool

path ended at. Mach won't allow this but this is exactly what I want it to

do.

To get around this I have to do a dummy G01 out away from the work and then

another G01 back to the same starting point. Thereafter, the circular pass

is allowed and worksfine. See Below.

G0 G49 G40 G17 G80 G50 G90

M6 T46 (TOOL DIA. 0.504)

G20 (Inch)

M03 S1000

G64

G00 G43 H46 Z0

(Right hand OD Climb)

X1.075 Y0.2875

G01 Z0.0625 F15

G01 G41 P0.25 X0.7875 F15

G03 X0.5 Y0 R0.2875

G02 X-0.5 Y0 R0.5 Z0

G02 X0.5 Y0 R0.5 Z-0.0625

G02 X-0.5 Y0 R0.5 Z-0.125

G02 X0.5 Y0 R0.5 Z-0.1875

G01 X1 Y0 * (this line added by me)

G01 X.5 Y0 * (this line added by me)

G02 X-0.5 Y0 R0.5 Z-0.1875 * (this line added by me)

G02 X0.5 Y0 R0.5 Z-0.1875 * (this line added by me)

G03 X0.7875 Y-0.2875 R0.2875

G01 G40 X1.075

G00 Z0

M5 M9

M30

Why does Mach make me go to this extra effort? It seems like a waste of time

and code. I think the problem is in Mach not Thread Wizard.

Thanks,

Mark