CNC Drilling Cycles (G81–G89): Complete Guide with Real G-Code Examples

Canned drilling cycles simplify repetitive hole-making operations. Instead of writing multiple lines of G-code, you can program drilling, pecking, tapping, and boring with a single block.

This guide covers G81–G89 with real-world examples for Fanuc, Haas, Siemens, and Heidenhain.

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📌 1. G81 — Simple Drilling Cycle

Basic drilling cycle: rapid to R-plane, feed to Z-depth, retract.

G81 R2.0 Z-15.0 F200
G80

• R2.0 = clearance plane
• Z-15.0 = final depth
• F200 = feedrate

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📌 2. G82 — Drilling with Dwell

Adds dwell at bottom of hole to improve accuracy.

G82 R2.0 Z-20.0 P500 F150
G80

• P500 = dwell time in milliseconds

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📌 3. G83 — Peck Drilling (Deep Hole)

Retracts between pecks for chip breaking.

G83 R2.0 Z-40.0 Q5.0 F180
G80

• Q5.0 = peck depth
• Z-40.0 = final depth

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📌 4. G84 — Tapping Cycle

Rigid tapping synchronized with spindle.

M29 S1000   (Rigid Tap Enable – Haas/Fanuc)
G84 R2.0 Z-20.0 F1.25
G80

• F1.25 = pitch per revolution (mm/rev)

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📌 5. G85 — Boring Cycle (Feed In/Out)

Smooth boring cycle, feeds in and out.

G85 R2.0 Z-30.0 F120
G80

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📌 6. G86 — Boring Cycle (Feed In, Rapid Out)

Feeds in, rapid retracts.

G86 R2.0 Z-25.0 F120
G80

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📌 7. G87 — Back Boring Cycle

Used for boring from the back side of hole (requires special tooling).

G87 R2.0 Z-15.0 F120
G80

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📌 8. G88 — Boring Cycle with Dwell

Feeds in, dwells, then manual retract.

G88 R2.0 Z-20.0 P1000 F100
G80

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📌 9. G89 — Boring Cycle with Dwell + Feed Out

Feeds in, dwells, then feeds out.

G89 R2.0 Z-20.0 P500 F100
G80

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📌 10. Siemens & Heidenhain Equivalents

• Siemens → CYCLE81 (drill), CYCLE82 (drill+dwell), CYCLE83 (peck), CYCLE84 (tap), CYCLE85–89 (boring)

CYCLE83(DEPTH=-40, PECK=5, RET=2, F=200)

• Heidenhain → CYCL DEF 200 (drilling), CYCL DEF 205 (peck), CYCL DEF 207 (tapping), CYCL DEF 209 (boring)

CYCL DEF 205 PECKING
Q200=+2   ; SAFETY HEIGHT
Q201=-20  ; DEPTH
Q206=+150 ; FEEDRATE
Q202=+5   ; PECK

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📌 11. Best Practices

• Use G98 (return to initial plane) or G99 (return to R-plane) carefully.
• Always apply coolant before drilling deep holes.
• For tapping, verify rigid tapping support on control.
• Peck cycles prevent chip packing and tool breakage.

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📌 12. Advanced Example — Bolt Circle Drilling

#100=0
WHILE[#100LT360]DO1
G81 X[50*COS[#100]] Y[50*SIN[#100]] Z-15. R2. F150
#100=#100+60
END1
G80

This macro drills 6 holes on a 50 mm bolt circle.

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📌 13. Future of Drilling Cycles (2025–2030)

• Adaptive peck cycles — spindle load determines Q-value dynamically.
• Smart tapping cycles — auto-adjust feed for pitch correction.
• AI-driven drilling optimization — reduces cycle time and improves tool life.

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✅ Conclusion

Drilling cycles (G81–G89) are essential for efficient CNC machining.

By mastering these cycles, you reduce program length, improve safety, and extend tool life — making your shop more productive and reliable.