828d Post Processor For Mastercam | Siemens

If you have a 5-axis or 3+2 machine with the 828D, the post must manage TRAORI (tool orientation management). Without it, rotary moves are dangerous. The post must insert TRAORI at the start of multi-axis paths and TRAFOOF at the end, then manage the kinematic chain.

Not all posts are created equal. When sourcing a Mastercam post for the 828D, watch for:

The 828D uses a fixed tool magazine (T= tool number, D= cutting edge offset). A basic post might output:

T5 M6

But a good 828D post outputs Siemens’ explicit syntax: siemens 828d post processor for mastercam

N100 T="5" ; Tool name
N110 M6
N120 D1 ; Activate cutting edge 1

It must also handle the D number correctly—something Mastercam’s tool table often decouples from the tool number.

Modern machining requires constant velocity and jerk control. The post should output:

CYCLE832(1, 0.1, 1)  ; Activate HSC with 0.1mm tolerance

Without this, your 3D contouring will be slow and choppy. If you have a 5-axis or 3+2 machine

Even experienced programmers make mistakes by assuming a "close enough" post. Here’s what goes wrong:

| Problem | Consequence | | :--- | :--- | | Missing $PATH=/_N_MPF_DIR | Machine cannot locate the program. | | Wrong G-code dialect (e.g., G2 vs. G3 with IJK absolute) | Unexpected arc directions, scrapping parts. | | No G40/G41/G42 compensation output | Tool diameter offsets ignored, causing dimensional errors. | | Hard-coded F (feed) without FGROUP | Feed per revolution vs. per minute mismatch on live tooling. | | Lack of SOFT or FFWOF | Poor surface finish due to excessive machine jerk. |

In the world of CNC machining, the toolpath is only half the battle. The other half is translation—converting the generic motion of CAM software into machine-specific, readable code. For shops operating Siemens 828D controllers with Mastercam, the Post Processor is the critical linchpin. Without a properly configured post, even a perfectly programmed part can result in collisions, alarm states, or surface finish errors. But a good 828D post outputs Siemens’ explicit

This article explores the architecture, customization, and best practices for developing or fine-tuning a Siemens 828D post processor for Mastercam.

For advanced 5-axis machining, Siemens uses the TRAORI command to activate transformation. The post processor must calculate the tool vector (A, B, C or I, J, K) and output it correctly.

If you have MP post processor experience, you can edit the .PST file. Critical sections to modify: