Establishing a tool length or work zero by moving the tool down or over until it just contacts a reference surface, a gauge block, a tool setter or a strip of paper, then entering the position. The paper method adds the paper's thickness, three to four thou for copy paper, which must be accounted for. CNC shops touch off every new tool and after every insert change or crash.
New drill in pocket twelve, touch it off on the setter before you hit cycle start or it'll go in deep.
If you touch off on paper, subtract its thickness every time, or every tool will cut a few thou shallow.
Also heard as
- touch-off
- pick up
Related terms
Work offset
The stored distance from machine zero to the part zero, so a CNC program runs from the right place.
Wiggler
Shop name for an edge finder or wobble-tip locator used to find part edges and lines on a mill.
Crash
To run a tool, holder or spindle into the part, vise or table by mistake, usually at rapid speed.
Bump
To make a small adjustment to an offset or position, usually a thou or less, to bring a size in.