A coordinate system saved in the CNC control, selected with G54 through G59 and their extended versions, that tells the machine where program zero sits on the part. The setup machinist finds the part datum with an edge finder, probe or indicator and enters it. Multiple offsets let one program run parts in several vises or fixtures, and a wrong or forgotten offset is a classic cause of crashes.
Second vise is on G55, did you update that work offset after you moved it, or are we about to cut air?
Write the offset number on the vise or fixture with a paint pen; it saves the next shift from guessing.
Also heard as
- fixture offset
- work coordinate system
- G54
Related terms
Touch off
To set a tool's position by bringing it to a known surface and recording that point in the control.
Fixturing
The design and use of fixtures that locate and clamp parts the same way every time.
Crash
To run a tool, holder or spindle into the part, vise or table by mistake, usually at rapid speed.
Prove out
To run a new CNC program cautiously the first time, watching every move to catch errors before they crash.