Mastercam Post Processor Editing: A Practical Guide A Mastercam post processor is the essential "interpreter" that translates your digital toolpaths into the specific G-code dialect your CNC machine understands. While stock post processors are often sufficient, customizing them can significantly improve efficiency, reduce manual G-code editing, and unlock machine-specific features. 1. Preparation and Safety
A Mastercam Post Processor is a text-based file that acts as a middleman. It takes the file—which contains the generic motion data (X, Y, Z, I, J, K) and operation flags—and reformats it into machine-specific G-code.
To change how numbers look (e.g., forcing a decimal point or padding trailing zeros), modify the format assignments ( fmt ).
When standard cycles like G81 or G83 do not suffice for specialized tooling (such as gun drills or back-spotfacers), you can map Mastercam's "Custom Cycles" to output personalized G-code strings. mastercam post processor editing
Before changing any lines of code, you must understand the file types and structures that Mastercam uses to generate G-code. File Extensions (.PST vs. .MP)
If you don't know why a post is skipping a line, force it to stop. Insert this debug code into the line you are testing: "M00 (DEBUG: Coolant turned on here)", e$ When your machine runs, it will stop, and you can see if the code appeared before or after your motion.
If your post includes a .PSB file, it is likely a or a specialized builder's post. You can edit the .PST for formatting (e.g., decimal places, coolant M-codes), but you cannot change the 5-axis kinematics or advanced drill cycles. For those, you must contact your reseller. Mastercam Post Processor Editing: A Practical Guide A
When editing a Mastercam post processor, keep the following best practices in mind:
Locate the numbering variables at the top of your post file: Set omitnc$ : yes$ to eliminate sequence numbers entirely. Set omitnc$ : no$ to enable them.
Mastercam provides a built-in post processor editor, which allows users to modify the post processor code. The editor is accessible through the Mastercam interface, and it provides a range of tools and features to facilitate editing. Preparation and Safety A Mastercam Post Processor is
Open the active .PST file in Code Expert and apply your changes.
If you need help adjusting a specific part of your G-code output, please let me know:
Adding or removing specific G-codes (like G21 for metric or G91 G28 Z0 for homing) at the start of a program.
Standardizing G-code headers ensures operators can identify the program name, part number, date, and tools required directly from the CNC control screen.
