Mastercam Post Processor Editing: A Comprehensive Guide
Mastercam is a popular computer-aided manufacturing (CAM) software used by machinists and manufacturers to create and optimize G-code for CNC machines. A crucial component of Mastercam is the post processor, which converts the CAM software's internal code into a format that can be read by the CNC machine. However, sometimes the standard post processor needs to be edited or customized to meet specific requirements. In this article, we'll delve into the world of Mastercam post processor editing and explore its importance, benefits, and best practices.
What is a Post Processor?
A post processor is a software component that translates the toolpath and machining operations generated by Mastercam into a G-code file that the CNC machine can understand. The post processor is responsible for:
Why Edit a Post Processor?
There are several reasons why you might need to edit a Mastercam post processor:
How to Edit a Mastercam Post Processor
To edit a Mastercam post processor, you'll need:
The post processor editing process typically involves:
Best Practices for Mastercam Post Processor Editing
When editing a Mastercam post processor, keep the following best practices in mind:
Conclusion
Mastercam post processor editing is a powerful way to customize and optimize your CAM workflow. By understanding the basics of post processor editing, you can improve CNC machine compatibility, add custom operations, and enhance efficiency. Remember to follow best practices, such as backing up the original post processor and thoroughly testing changes. With this guide, you're ready to dive into the world of Mastercam post processor editing and take your machining operations to the next level.
Additional Resources
By providing a comprehensive overview of Mastercam post processor editing, this article aims to serve as a valuable resource for machinists, manufacturers, and CAM software users. Whether you're a seasoned expert or just starting out, this guide will help you navigate the world of post processor editing and unlock the full potential of your Mastercam software.
Mastering the Mastercam post processor (the .pst file) is often the difference between a programmer who just "gets by" and one who runs a high-efficiency shop. By editing your post, you eliminate manual "hand-edits" at the machine, which are error-prone, time-consuming, and dangerous. 1. Essential Safety: Always Backup First
Before touching a single line of code, make a copy of your original post processor files.
Rename the Copy: Give it a clear name like original_fanuc_backup.pst.
The "Gold" Rule: If your edits break the code, you must have a clean version to revert to immediately to avoid machine downtime. 2. Choosing the Right Editing Tools
While a post processor is just a text file, standard Notepad can be limiting for complex logic.
Mastercam Code Expert: The default NC editor included with Mastercam. It features multi-stream functions and built-in variables.
Notepad++ or VS Code: These are favorites for "heavy lifting" because they offer custom code highlighting and split-screen "Compare" functions to see exactly what changed between two versions.
CIMCO Edit: Often bundled with Mastercam, this is excellent for comparing edited code files side-by-side. 3. Understanding "Post Switches"
Many modifications don't require rewriting complex logic. Instead, look for Post Switches at the top of the file.
What they are: Simple variables (usually 0 for Off, 1 for On) that control standard behaviors.
Common Edits: Removing block numbers (N-numbers), changing IJK to R-values for arcs, or enabling/disabling high-speed machining cycles.
Where to find them: Look for sections labeled "General Output Settings" or "Job Setup Switches". 4. Advanced Customization & Debugging
For deeper edits—like changing tool change sequences or adding custom M-codes—you’ll need to work with the MP language. How to edit post processors - eMastercam.com
Editing Mastercam post processors (the files) is a powerful way to tailor G-code output to your specific CNC machine. While there isn't one "perfect" article, several high-quality resources and expert tips provide a comprehensive guide to the process. The Best Tool for Editing: Mastercam Code Expert Most pros agree that the Mastercam Code Expert is the best environment for editing posts. eMastercam.com Why use it:
It includes built-in recognition for predefined variables and operators, color-coding them to help you avoid typos. How to access: File > Edit/Open external within Mastercam and select your eMastercam.com Essential Editing Tips from the Pros Always Backup First:
Never edit your "live" post without a safety copy. Rename your working file (e.g., Post_v1_Edited.pst ) so you can always revert if the code breaks. Use the Post Debugger:
To see exactly which line of the post processor is generating a specific line of G-code, enable the Post Debugger . In Mastercam, go to File > Configuration > Post Dialog Defaults
and check "Enable post debugger". When you post code, click the ladybug icon to step through the logic. Check "Post Switches" First: mastercam post processor editing
Many common changes (like turning off tool pre-calls or changing G-code formats) are already built-in. Look at the top of the file for a "switches" table where you can simply change a to toggle features. Note Your Changes: Use a unique character (like a pound symbol
or your initials) to mark every change you make. This makes it easy to search for your modifications later. Top Resource Links adding / editing tool comments - eMastercam.com
Register now to participate in the forums, access the download area, buy Mastercam training materials, post processors and more. * eMastercam.com Opening a post for editing - eMastercam.com
Mastercam Post Processor Editing: A Comprehensive Guide
Mastercam is a popular computer-aided manufacturing (CAM) software used by machinists and manufacturers to create and optimize G-code for CNC machines. One of the key components of Mastercam is the post processor, which plays a crucial role in converting the CAM software's output into a format that can be read by the CNC machine. In this article, we will explore the world of Mastercam post processor editing, including its importance, basic concepts, and step-by-step editing techniques.
Why Edit Mastercam Post Processors?
Post processors are essentially translators that convert Mastercam's output into a specific CNC machine's language. While Mastercam provides a range of built-in post processors for various CNC machines, there may be instances where a custom post processor is required. This could be due to:
Basic Concepts of Mastercam Post Processors
Before diving into post processor editing, it's essential to understand the basic concepts:
.ppr extension that contain the code that translates Mastercam's output into CNC machine code.Step-by-Step Guide to Editing Mastercam Post Processors
Editing a Mastercam post processor requires a basic understanding of programming concepts and the post processor syntax. Here are the general steps:
Common Post Processor Editing Tasks
Some common tasks that may require post processor editing include:
Best Practices and Tips
When editing Mastercam post processors, keep the following best practices and tips in mind:
In conclusion, Mastercam post processor editing is a powerful way to customize and optimize the output of your CAM software. With a basic understanding of post processor concepts and syntax, users can make targeted changes to improve the machining process. By following best practices and tips, users can ensure that their edited post processors produce accurate and efficient G-code for their CNC machines.
Editing a Mastercam post processor (the .pst file) allows you to customize the G-code output to match your CNC machine's specific requirements. 1. Preparation & Safety
Always backup: Before making any changes, create a copy of your original .pst file and rename it (e.g., Original_Post.pst.bak).
Locate the file: Post processors are typically found in the Shared Mastercam\Posts directory on your computer.
Use the right editor: Use the Mastercam Code Expert for syntax highlighting or a text editor like Notepad++. To open it from Mastercam, go to File > Edit/Open External. 2. Common Editing Tasks
Post Processor Editing Class - CAD / CAM - Practical Machinist
Editing Mastercam post processors allows you to customize G-code output to perfectly match your CNC machine’s requirements, reducing the need for risky manual code modifications. Safe Editing Practices
Always Create a Backup: Before making any changes, copy your original .pst file and store it in a safe location.
Use Proper Tools: While standard text editors work, Mastercam Code Expert is recommended for its built-in recognition of variables and operators.
Utilize the Debugger: Enable the debugger in Mastercam to step through the post-processing routine. This helps you identify exactly which part of the post processor code is generating specific lines of G-code. Common Customization Steps
Open the File: Locate your post processor file (typically with a .pst extension) in the Shared Mastercam directory. Identify Modifications: Common edits include:
Tool Change Logic: Adjusting commands to match specific machine tool changer requirements.
Spindle & Coolant Control: Modifying M-codes (e.g., changing coolant start/stop timing).
Custom Macros: Adding safety checks or proprietary machine functions.
Test with Simple Toolpaths: After saving changes, test the post on a simplified part with only one or two toolpaths to verify the output before running it on a machine. Advanced Support and Resources Mastercam Post Processor User Guide - CLaME
Mastercam Post Processor Editing: A Guide to Customizing G-Code
In Mastercam, a post processor acts as a translator, converting the generic toolpath data from your CAM software into machine-specific G-code that your CNC controller understands. While Mastercam offers thousands of ready-to-use posts, manual editing is often required to fine-tune machine behavior, automate safety retracts, or integrate custom macro logic. The Core Components of a Mastercam Post Why Edit a Post Processor
A functional "post" in Mastercam isn't just one file; it is typically comprised of three essential elements:
Machine Definition (.mcam-control): Defines physical machine attributes like travel limits and axis orientation.
Control Definition (.mcam-mmd): Specifies the formatting of the G-code, such as arc support and decimal precision.
PST File (.pst): The primary script file containing the logic and formatting rules for G-code output.
PSB File (.psb): Some custom or advanced posts include an encrypted "binary" file that contains protected logic you cannot edit directly. How to Edit a Post Processor
Editing a post is essentially a scripting task. You can modify these files using any text editor, though many developers use specialized editors like Mastercam Code Expert or CIMCO Edit for syntax highlighting.
Locate the File: Post files are usually found in the C:\Users\Public\Documents\shared Mastercam 20xx\Posts directory.
Backup Your Post: Always create a copy of your .pst file before making changes. One misplaced character can cause machine crashes or output errors.
Open and Search: Open the .pst file in your editor. Most edits involve searching for "post blocks" (sections starting with p) such as: pheader: Controls the very beginning of the G-code program. psof: "Start of file" logic for the first tool change. ptlchg: Logic used for subsequent tool changes. peof: "End of file" commands like parking the machine.
Test and Debug: After saving, post-process a simple toolpath in Mastercam and inspect the G-code to ensure the changes appear as expected. Some advanced users use debugging tools to step through the post logic line-by-line. Common Customizations
Safety Lines: Adding or removing specific G-codes (like G21 for metric or G91 G28 Z0 for homing) at the start of a program.
Coolant Codes: Changing how and when M08 (flood) or M07 (mist) are triggered.
Custom Macros: Integrating advanced automation like tool life management or probing cycles directly into the posted code.
Comments: Formatting how tool names and operation notes appear in the G-code for the operator. Professional Support vs. DIY
While minor edits (like changing a text string) are common for users, complex multi-axis posts (4-axis or 5-axis) often require expert intervention. Many shops work with their Mastercam Reseller to develop custom posts, as errors in complex kinematic logic can lead to expensive machine damage.
For those looking to master this skill, specialized training programs cover Fanuc, Haas, and Siemens logic, teaching users how to build IF/WHILE loops and math-driven cycles into their posts.
Mastercam Post Processor Editing Guide Mastercam post processor editing is a vital skill that bridges the gap between your CAM toolpaths and the specific physical requirements of your CNC machine. By customizing post processors, you can eliminate manual "hand-editing" of G-code, which reduces errors and optimizes machine performance. Understanding the Post Processing System
In Mastercam, "posting" is governed by three primary interconnected files: Machine Definition (.mcam-mmd):
Defines the physical geometry and kinematic layout of the machine (e.g., axes, rotary limits). Control Definition (.mcam-control):
Determines how the control handles specific code types, such as arcs, drilling cycles, and subprograms. Post Processor (.pst):
The scripting file that formats the actual NC output according to the machine's syntax requirements. Key Tools for Editing
Successful editing requires using the right software environment to avoid syntax errors:
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
Before making any changes to a post processor file, follow these non-negotiable safety steps: Create a Backup : Always copy your existing
file to a secure location before editing. If an edit fails, you must be able to revert to a working version. Use the Right Editor : Mastercam includes Code Expert
, which provides syntax highlighting specifically for the MP (Mastercam Post) language.
: If you are sending your post to a reseller for professional editing, use the
utility to package your machine definition, control definition, and post file together. 2. Common Editing Methods
Depending on the complexity of your needs, there are three primary ways to modify how Mastercam outputs code: Post Switches
Many post processors include a "switch" section at the top of the file. These are simple variables (usually
) that toggle features on or off without requiring complex programming.
: Enabling/disabling stage tool changes, toggling between IJK and R for circular interpolation, or turning off line numbers (N-numbers). The Mastercam MP Language If the Post is wrong
For deeper customization, you must edit the logic within the file using Mastercam’s proprietary MP scripting language. Mastercam Post Processor User Guide - CLaME
In Mastercam, post processor editing is the process of customizing the script that translates CAM toolpath data into machine-specific G-code for a CNC machine. This ensures the output is perfectly compatible with a specific machine controller's requirements, such as including custom tool tables or specific canned cycles. New York University Key Components of a Post
A complete "post" typically consists of three primary files:
: The main script containing the logic for G-code generation. Machine Definition : Defines the physical parameters and axes of the machine. Control Definition
: Sets the rules for how the controller interprets code, such as arc formatting or drilling cycles. support.qtemfg.com How to Edit Mastercam Posts
You can modify these files using several different tools depending on your technical comfort level: Mastercam Code Expert
: The built-in editor specifically designed for viewing and editing Post Developer Kit (PDK)
: A dedicated professional toolset provided by Mastercam for creating and managing advanced post processors. External Text Editors : You can use editors like Visual Studio Code
for manual script editing, provided the file is not encrypted (non- Machine/Control Definition Manager
: Accessible directly within Mastercam for adjusting settings without manual coding. New York University Common Customizations Tool Tables
: Modifying the post to automatically pull tool names or bin locations into the header of the G-code. Custom M-Codes
: Adding machine-specific commands like air blasts (e.g., M83) or coolant triggers. Axis Rotation
: Adjusting the post to support multi-axis movements like 3+2 or full 5-axis simultaneous motion.
For complex edits, Mastercam provides official guides through their Help files and community support on forums like New York University Are you looking to make a specific change
to your G-code output, such as adding a custom header or changing how tool changes are handled? Mastercam Post Processor User Guide - CLaME
.pst. Save it as MyMachine_EDIT_2024.pst..PSB files. If you have a .psb with the same name as your .pst, editing the .pst may have zero effect because the binary overrides it.The Problem: Your post outputs the tool length offset (H) only on the first tool. If you restart mid-program, the machine forgets the offset.
The Solution: Modify ptlchg$ (Tool Change) block.
Find:
ptlchg$ #Tool change
pbld, n$, "T", t$, "M06", e$
pbld, n$, "S", spindlspd, "M03", e$
Add the line:
ptlchg$ #Tool change
pbld, n$, "T", t$, "M06", e$
pbld, n$, "G43", "H", t$, e$ # <--- ADD THIS LINE
pbld, n$, "S", spindlspd, "M03", e$
⚠️ Warning: Ensure t$ is the correct variable for your H offset (sometimes it is tloffno$).
If you’ve been in CNC machining for more than a week, you’ve likely heard the phrase: “It’s just a post thing.”
In the world of Mastercam, the Post Processor is the silent gatekeeper between your CAM toolpath and your machine’s motion. When it works, you never think about it. When it fails, it crashes tools, scraps parts, or stops the spindle cold.
Editing a Mastercam Post Processor (.pst and .psb files) isn’t just a technical skill—it’s a survival skill for any shop that wants to move beyond generic G-code.
Here is everything you need to know about why, when, and how to edit your Mastercam Post.
# symbol to leave notes for your future self.# CUSTOM EDIT: Changed from M08 to M88 for thru-spindle coolant on 2026-04-13
if coolant$ = 1, pbld, n$, "M88", e$ # Was M08
pheader$ and psof$This is the most critical safety zone. This controls what appears before the first movement.
Original:
psof$ # Start of file for non-zero tool
pbld, n$, "G00 G17 G40 G80 G90", e$
Edited (Adding a custom safe start):
psof$
pbld, n$, "G20" (Inch mode)
pbld, n$, "G90 G80 G40 G17" (Absolute, cancel canned cycle/cutter comp)
pbld, n$, "G91 G28 Z0." (Send Z home)
pbld, n$, "G90 G54" (First work offset)
pbld, n$, "M01" (Optional stop for operator check)
e$
The NCI file is text-based (in older versions) or binary/compressed (in newer versions), but conceptually it streams data in records.
1000 record: Linear movement (XYZ coordinates).2000 record: Arc movement (center point, radius, plane).10000 record: Tool change parameters.A Post Processor is a translator. Mastercam speaks an internal, generic language called NCI (Numerical Control Intermediate). Your Haas, DMG MORI, or Mazak speaks a unique dialect of Fanuc, Heidenhain, or Siemens.
The Post takes the NCI data (e.g., "cut a 0.5" hole at X1.0 Y1.0") and converts it into a line of G-code specific to your machine.
Example translation:
G83 G98 X1. Y1. Z-0.5 R0.1 Q0.1 F10.L X1. Y1. R0 FMAX ... CYCLE 208If the Post is wrong, the G-code is dangerous.