Printed from Kezuriba (kezuriba.net/en/nc/g02/)

G02

Machining center, LatheModal, group 01

Circular interpolation, clockwise (CW) / helical interpolation

⌨Format and notes

G17 G02 X_ Y_ R_ (or I_ J_) F_ / lathe: G02 X(U)_ Z(W)_ R_ (or I_ K_) F_

Direction is as seen from the + side of the selected plane (the +Z side for G17)
I/J/K are incremental distances from the start point to the arc center (incremental regardless of G90/G91)
With R, the center error becomes large for arcs close to a semicircle or full circle. Write a full circle with I/J/K (it cannot be written with R)
Some controls use a negative R to denote an arc over 180° (NIST, FANUC-type)

Diagram: G02 arc: direction, center, I/J, R

The tool travels clockwise around the center from start to end (figure is viewed from the +Z side in G17, i.e. from above). Helical interpolation adds a simultaneous linear Z move to this arc. For a lathe (G18), the direction is the same in a drawing with X+ up and Z+ to the right.

📚Sources

The meaning shown agrees in at least two sources (agreement confirmed). Explanations are written in our own words.

Mitsubishi Electric — The Basics of CNC Machining Programming (for Machining center) e-Learning material (PDF) mitsubishielectric.com
Mitsubishi Electric — The Basics of CNC Machining Programming (for Lathe) e-Learning material (PDF, BNP-C8027-688) mitsubishielectric.com
Siemens AG — SINUMERIK 802D sl/840D/840D sl/840Di/840Di sl/810D Programming Manual ISO Milling, 04.2007 Edition (6FC5398-7BP10-0BA0) cache.industry.siemens.com
Haas Automation, Inc. — Mill Operator's Manual – 17 Mill G-Codes (online version) haascnc.com
Haas Automation, Inc. — Lathe Operator's Manual – 16 Lathe G-Codes (online version) haascnc.com
National Institute of Standards and Technology (NIST), USA — The NIST RS274NGC Interpreter – Version 3 (NISTIR 6556, 2000) nvlpubs.nist.gov
Ministry of Health, Labour and Welfare (MHLW), Human Resources Development Bureau, Office of the Councillor for Skills Evaluation — Human resource development manual using the practical exam tasks of the Grade 3 Skilled Worker Test: CNC lathe work (March 2018) waza.mhlw.go.jp