VideoVideos G and M codes used in CNC Machining By Akhilesh - June 18, 2021 0 1015 Share Facebook Twitter Google+ Pinterest WhatsApp Closeup of generic CNC drill equipment. 3D illustration. _engineinside CNC Machines uses numbers, letters and different alphabets known as codes. These codes are used to control the machine for machining purpose. Watch the video for commonly used codes in Milling and Turning operations.