Printed from Kezuriba (kezuriba.net/en/nc/g99/)

G99

Machining center, LatheModal, group 10

Canned cycle: return to R point

⌨On machining centers

G99 G81 X_ Y_ Z_ R_ F_

After drilling, stays at the R point height and moves to the next hole. Saves time if there are no obstacles
If there is a clamp in the path, leaving G99 active causes a collision

Diagram: Height to move to the next hole after drilling

G98 returns to the initial point (the height before entering the cycle) after drilling and then moves to the next hole. G99 moves at the R point height, which is faster, but collides with a clamp or step in the way.

◎On lathes: Feed per revolution (mm/rev) (G-code system A)

The same number means something different on lathes (FANUC-type G-code system A). Group 05.

G99 G01 Z_ F_ (F is in mm/rev)

This is the normal cutting mode on lathes (all examples in the Mitsubishi lathe material and MHLW material use mm/rev)

≠Differences between controls and machines

The same code can be written or assigned differently depending on the CNC control and the machine builder. Always check your machine’s manual.

Source	Machine	Item	Detail
Haas	Lathe	Group	10
Siemens (ISO dialect)	Lathe	Meaning	In system B: R point return in drilling cycles. Feed per revolution is G95

📚Sources

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

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. — G-code, M-code, and Setting (per-code explanation pages) haascnc.com
Haas Automation, Inc. — Mill Operator's Manual – 17 Mill 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
Mitsubishi Electric — The Basics of CNC Machining Programming (for Lathe) e-Learning material (PDF, BNP-C8027-688) mitsubishielectric.com
Haas Automation, Inc. — Lathe Operator's Manual – 16 Lathe G-Codes (online version) haascnc.com
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
Siemens AG — SINUMERIK 802D sl/840D/840D sl/840Di/840Di sl/810D Programming Manual ISO Turning, 04.2007 Edition cache.industry.siemens.com