Before you edit it, you must understand it.
If your post outputs the wrong values, turn on debugging variables at the top of your post script. Setting bug1$ = 1 or bug2$ = 1 will output the NCI line numbers directly into your G-code file. This tells you exactly which Mastercam operation block triggered the faulty code. Best Practices and Safety
Editing Mastercam post processors is a targeted, technical task that adapts CAM output to machine-specific requirements. Follow a disciplined workflow: backup, small iterative edits, thorough simulation, and controlled on-machine testing. Properly managed posts reduce machining errors, improve cycle reliability, and standardize shop practices.
Define the data (e.g., speed, feed, coordinates). mastercam post processor editing
: Adding safety checks or proprietary machine functions.
Lines starting with a hash ( # ) are comments. They do not generate code but are critical for documentation. Always add your initials and date when you make a change. Pro Tip: A revision log at the top of the file is the first place help-desk technicians look to see what broke .
Before making any changes to a post processor file, follow these non-negotiable safety steps: Create a Backup : Always copy your existing Before you edit it, you must understand it
A lightweight alternative. You can download custom user-defined language (UDL) files for Mastercam MP syntax highlighting.
| | Find this variable/block | Change to this | | :--- | :--- | :--- | | Remove "N100" lines | omitseq$ | yes$ | | Remove "O0000" (program number) | pprog$ block | Comment out "O", progno$ | | Force G43 H on every tool | psof$ or ptlchg$ | Ensure *tlngno$ is present, not commented | | Turn off the G43 line entirely | psof$ | Look for "G43" , add # in front of the line | | Add a custom comment (SAMPLE) | pheader$ | " (SAMPLE)", e$ | | Change G28 to G91 G28 | pretract block | Look for "G28" ; change to "G91" , "G28" | | Output decimals for inches only | fs2 definitions | Create one format without decimal point for integers. | | Suppress the "D" comp on lathe | ptoolend$ | Find *tldia$ or cc_pos$ ; comment it out. |
fs2 1 0.7 0.6 # Default for decimal fs2 2 0.4 0.3 # Absolute, 4 place decimal (This is the bad one) This tells you exactly which Mastercam operation block
: Adjusting commands to match specific machine tool changer requirements.
For deeper customization, you must edit the logic within the file using Mastercam’s proprietary MP scripting language. Mastercam Post Processor User Guide - CLaME
Your controller chokes on I/J/K arc definitions (typically for older controls or routers) or prefers R values.