Use a backplotter or CNC simulator first.

"Mike, there's no 'download button' for a generic post that works perfectly on your specific machine. A post processor is a translator — it converts Mastercam’s toolpath NCI data into the exact dialect of G-code your machine’s controller understands. For Mastercam 2018, posts are tied to the version and your machine's parameters."

Your control definition is wrong. Go to Machine Type → Edit Control Definition → Work Coordinates . Set the default to G54 (offset 1). Save and repost.

Mastercam 2018 was a robust release that introduced significant interface changes and enhancements to the Mastercam Add-Ons (like the Mill-Turn module). However, software ages quickly. Mastercam is currently on an annual release cycle, meaning Mastercam 2018 is several versions behind the current standard.

menu to update them correctly. This utility ensures that the legacy code is compatible with the 2018 architecture. Post Processing for CAD/CAM Software: Your Complete Guide

For Mastercam 2018, the only official download location is or your authorized reseller . Everything else is a gamble with your machine, your job, and your safety.