I am still a noobie and am using Mastercam X5 with Mach 3. I have drawn a 6" x 12" rectangle in Mastercam and set the tool to .125 and set it to left offset with a clockwise rotation (outside perimeter). When I view the NC code it shows G40 at the top (along with a few others). When I import that into Mach 3 the G40 disappears and my cut is too small.

I have looked through the Mach 3 manual (section 7, 9, and 10) but haven't found anything that stands out. Is it best to est this in Mastercam or in Mach 3? I tried setting it in Mach 3 and I still get no offset.

Any ideas? What am I doing wrong?

Normally CAM will produce true toolpaths, ie you tell it what dia tool you will be using and the CAM will produce a toolpath offset the correct amount and thus there is no need to use tool dia offsets in Mach.
Hood

Thanks Hood but I have done that. We have several CNC's at work and we use Mastercam. I talked to the CNC Supervisor and he verified that I set the cutter compensation properly but when I import the DXF into Mach 3 the line showing the G code for the cutter is gone.

Here are the first few lines from the Mastercam NC file.

%
O0000(LICENSE PLATE 5 - COPY)
(DATE=DD-MM-YY - 17-08-12 TIME=HH:MM - 19:03)
(MCX FILE - C:\USERS\DAN\DESKTOP\DRAWINGS\***************************X - COPY.MCX-5)
(NC FILE - C:\USERS\DAN\DOCUMENTS\MY MCAMX5\ROUTER\NC\*************************** - COPY.NC)
(MATERIAL - WOOD INCH)
( T1 |   1/8 STRAIGHT BIT | H1 )
N100 G17 G20 G90 G40 G80 G64 G49 G0 M05
N102 G8 P1
N104 G90 M05 Z0
N106 G52 X0. Y0. Z0.
N108 T1 M6
N110 G0 G90 G54 X.375 Y6.3125 C0.
N112 S18000 M3
N114 G43 H1 Z.25
N116 Z.1
N118 G1 Z0. F100.


And here is the same file after importing it into Mach 3:

(*************************** 5 )
(Tuesday, August 14, 2012)
G90G80G49
G0 Z0.200
G90.1
S0
G0 Z0.200
G0 X0.5000 Y0.0000
F1.000 G1 Z-0.090

I edited the Mach 3 file after importing it. The only values I changed were the Z values. Initially it had Z traveling up to +1.000 when moving so I changed that to +0.200 for time saving and the Z down was 0.000. I set my material surface to 0.000 so I manually changed that value to the thickness of my material, -0.090.

I am looking through the Mastercam manual now to see if I missed something but according to my source at work it is fine. BTW-I don't run the CNC's at work, I only ix the computers and network

What do you mean by

And here is the same file after importing it into Mach 3:

Are you meaning you open the exact same file or are you meaning you are using the same drawing but a different post processor to write the code for Mach?
If the former I fail to see how that can possibly be the case if the code is written as you have tped above when you open the file in notepad or similar.
If the latter then it is the post processor that is the issue.
If you can attach the first file I will see if it works here.
Hood

Not sure I understand your question. I created the drawing in Mastercam and chose the machine type as router. Then chose toolpath as contour. I then set my chain and 'manually' set the tool to .125. I just now selected the box that says 'select library tool'. Not sure if that will make a difference.

When I am done I save the drawing as a DXF, then go to my CNC computer and import the DXF into Mach 3. I guess that means I use Mastercam as my post-processor? Am I missing a step? It cuts it perfectly but about .125 too narrow and short.

The slots in the rectangle are also bigger than they should be. I have them set to about 1.000 x .250 but the are closer to about 1.100 x .350.
 
I have attached my NC file.

What version of Mach are you using?
You can not import DXF into Mach now and have not been able to do that for many years. If wanting to import a dxf into Mach you have to use LazyCAM.

If you have MasterCAM then it would be more sensible to use it to produce the code from the toolpaths you have drawn and it will then produce the code which you can then open in Mach.

The file you have attached would seem to be produced by MasterCAM so if you open it in Mach it should work correctly. This is how it shows to me when I open it in Mach, does this look correct?

Hood

Looks close. I am using Mach 3 but not sure which revision without looking. I'll run down in a few minutes to verify.

I am messing with Mastercam now and when I hit G1

in the Operations Manager I get a message stating a Partial NCI output file. Not all operations for *********XX/*********XX/******************X.NCI have been selected for posting. Post all?

Not sure why I get this message.

I will re-import this new DXF into Mach 3 and get that Mach code also.

Just open the file you attached in Mach, use the Load Code button then browse to where you have it stored. If Mach is looking for a file other than a nc then just choose All Files from the drop down menu in File Types and you should then see it.
Hood

My Mach3isR1.84.

So you say to load the NC file into Mach and not the DXF?

That is correct, the nc file is the code that your CAM has produced for you. Importing a dfx means you have simply used the CAM as a CAD programme and you are then using Mach to import the dxf and produce the code.
That version is very old, probably 6 years old and I would suggest you upgrade Mach to the latest lockdown.
I cant really recall if you had tool offset options when importing the dxf into that old version of Mach but I think it likely you didnt so any dxf imported would need to be of the toolpath rather than the part dimensions. As said though that is kind of a moot point as you have CAM and should really be using it to do what its meant to.
Hood