[tikka308]

I had to reinstall XP on my CNC computer. I properly backed everything up (including my Mach 3 files) and the reinstall went fine. I've installed the newest version of Bobcad V22 (v22.43.007_update.exe) and then went to their support site to download the newest Mach 3 post (http://s229444871.onlinehome.us/bobc...%20032608).exe)

Something is goofy with my post - it's driving the toolpath to the corner of the table. I know it's the new post because all of my old G code is just fine.

Here's an example: a 2" square with 0.25" radius being profiled with no tool compensation with a 0.25" endmill. The resulting Gcode is below.

Can someone please advise? Line N06 and N07 bother me, but I'm not experienced enough to diagnose. Thanks.

(BEGIN PREDATOR NC HEADER)
(MACH_FILE=YASNAC - 3AXVMILL.MCH)
(MTOOL T1 S1 D.25 H5.)
(SBOX X-1.25 Y-1.25 Z-1. L2.5 W2.5 H1.)
(END PREDATOR NC HEADER)

%
O100 (PROGRAM NUMBER)
(PROGRAM NAME - BOBCAD3.NC)
(POST - MACH 3)
(DATE - FRI. 05/23/2008)
(TIME - 08:28PM)


N01 G20 G40 G49 G54 G80 G90

N02 G28 Z0.
N03 G28 X0. Y0.

(JOB 1 CONTOUR)
(TOOL #1 0.2500 ENDMILL ROUGH)

N04 M06 T1
N05 M03 S748
N06 G00 G90 G54 X-.75 Y-1.
N07 G43 H1 Z.1 M08

N08 G01 Z-.135 F1.7968
N09 X.75 F2.9947
N10 G03 X1. Y-.75 I0. J.25
N11 G01 Y.75
N12 G03 X.75 Y1. I-.25 J0.
N13 G01 X-.75
N14 G03 X-1. Y.75 I0. J-.25
N15 G01 Y-.75
N16 G03 X-.75 Y-1. I.25 J0.
N17 G00 Z.1
N18 M05
N19 M09

N20 G28 Z0.
N21 G28 X0. Y0.
N22 M02

N23 M30
%

[Swag]

N06 G00 G90 G54 X-.75 Y-1. <---This is the work offset
N07 G43 H1 Z.1 M08 < ---This is the height offset, safe Z and coolant on

Hope it helps
Mark

[tikka308]

Thanks Swag. Here are two pictures: The first is of the part & toolpath in BobCAD. The 2nd is the Gcode in Mach3 - you can see where I've pointed out the "extra" Gcode/toolpath that is being included... Any thoughts?

[tikka308]

The problem seems to be the inclusion of "G28" - anyone know why the post is including this?

[tobyaxis]

The problem seems to be the inclusion of "G28" - anyone know why the post is including this?

Yes, because most cnc's change tools at the home or atc position. My machines at work use a G30 (second reference point return) to change tools like Mazaks. You should have a tool change position for your cnc so you don't have trouble doing a manual tool change.

Simply edit the G28 in the post processor to solve your problem.

[tikka308]

Toby - thanks! I have never edited a post myself, but did a quick search, downloaded the PDF, and found that it's really not too difficult at all! Problem solved. Thanks!

[HMB3000]

You should have a tool change position for your cnc so you don't have trouble doing a manual tool change..

Given the fact that his mill does not have a tool charge. the G28 could be alter in the post to read like G28 X12 Y0 for a tool change position or you can just delete the G28 line from your post