Incremental Programming (G91)

Definition

Coordinate values are referenced from the current position. Use it when each move should be measured from the current position rather than from the fixed datum.

Formula / Rule

• G91 means each commanded X, Y, and Z value is interpreted as an incremental distance from the current point.
• Cancel or replace it with G90 before restart blocks if absolute positioning is required again.

Typical Range

• Best for repeated step moves, pattern loops, and compact local repositioning logic.

Shop-floor Scenarios

• Use it in subprograms that step through repeated pitch or slot patterns.
• Pair it with clear comments when operators may restart inside the sequence.

Common Errors / Troubleshooting

• If the tool keeps drifting away from nominal, check whether an incremental block was replayed twice.
• If recovery is unsafe, return to a known position and re-establish G90 before continuing.

Related Tools

• G/M Code Reference
• G-code Viewer