G90.1/G91.1: IJK absolute/incremental mode

Defines whether the I/J/K arc centers are interpreted as absolute or incremental.

For reference only: syntax changes with the control, the post-processor and the machine parameters. Check the official manual and run a simulation before cutting. Legal notice.

Family: Arcs
Machine: Milling, Turning, Mill-turn
Risk: High
Example: G91.1 G02 X20 Y0 I10 J0

G90.1/G91.1

Arcs

IJK absolute/incremental mode

E.g.:

G91.1 G02 X20 Y0 I10 J0

Machine: Milling, Turning, Mill-turnRisk: High

Fanuc · Haas

G90.1 / G91.1

Fanuc: An incorrect mode completely changes the programmed arc.
Haas: Confirm default control/post processor setting.

Frequently Asked Questions (FAQ)

What does G90.1/G91.1 mean in a CNC program?

Defines whether the I/J/K arc centers are interpreted as absolute or incremental. In the catalogue it appears as "IJK absolute/incremental mode", within the Arcs family.

How is G90.1/G91.1 written on each control?

Fanuc: G90.1 / G91.1 · Haas: G90.1 / G91.1. The exact syntax depends on the control version and the machine parameters: always confirm with the manufacturer's manual.

Can you give me an example of G90.1/G91.1?

G91.1 G02 X20 Y0 I10 J0 — Defines whether the I/J/K arc centers are interpreted as absolute or incremental.

Which machines use G90.1/G91.1?

G90.1/G91.1 is used in: Milling, Turning, Mill-turn.

What should you watch out for with G90.1/G91.1?

High risk: a mistake here can cause a crash, a broken tool or an out-of-tolerance part. Simulate the program and dry-run it before cutting.

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