G80 to G89: Complete Guide to CNC Drilling and Boring Canned Cycles

G80 to G89: Complete Guide to CNC Drilling and Boring Canned Cycles

Canned cycles simplify repetitive machining operations like drilling, boring, tapping, and retract moves. Instead of writing multiple G-code lines for each operation, you can use a single canned cycle block.

---

📋 G-Code Overview

Code	Operation	Description
G80	Cancel cycle	Deactivates all canned cycles
G81	Drilling	Simple drilling with single depth
G82	Drilling with dwell	Pauses at bottom of hole
G83	Peck drilling	Breaks chips and retracts between pecks
G84	Tapping	Synchronized tapping cycle
G85	Boring	Feed in, feed out
G86	Boring (spindle stop)	Feed in, spindle stop, rapid out
G87	Back boring	Requires custom parameters
G88	Boring with dwell	Feed in, dwell, manual retract
G89	Boring with dwell	Feed in, dwell, feed out

---

🧠 Common Parameters (Fanuc-style)

G8x X__ Y__ Z__ R__ F__ Q__ P__

Parameter	Meaning
X/Y	Hole location
Z	Final depth
R	Retract/start plane
F	Feedrate
Q	Peck depth (for G83)
P	Dwell time (for G82, G88, G89)

---

🔨 G81 – Simple Drilling

G81 X50 Y50 Z-10 R2 F100

• Drills to Z-10 from retract plane R2
• At 100 mm/min feedrate
• No dwell or pecking

Cancel with: G80

---

⏱️ G82 – Drilling with Dwell

G82 X50 Y50 Z-12 R2 P300 F120

• Same as G81, but dwells for 0.3 sec at bottom
• P300 = 300 milliseconds

---

🪓 G83 – Peck Drilling (Chip Breaking)

G83 X30 Y30 Z-15 R2 Q5 F90

• Peck depth: 5mm (goes down in steps)
• Ideal for deep holes or chip-prone materials

Peck sequence:
Z-5 → retract → Z-10 → retract → Z-15 → retract

---

🔩 G84 – Tapping Cycle

G84 X60 Y60 Z-12 R2 F1.25

• Performs synchronized tapping with pitch = 1.25mm
• Feedrate must match spindle speed × pitch

🛑 Make sure your machine supports rigid tapping

---

🔁 G85 – Boring (Feed In/Out)

G85 X40 Y40 Z-10 R2 F80

• Bores in at feedrate, and returns at same feedrate
• Unlike drilling, this is smoother and used for finishing

---

🔄 G86 – Boring with Spindle Stop

G86 X25 Y25 Z-10 R2 F80

• Enters at feedrate
• Spindle stops at bottom
• Retracts at rapid speed

Good for older lathes or rigid boring setups

---

⏸️ G89 – Boring with Dwell + Feed Out

G89 X20 Y20 Z-10 R2 P500 F80

• Adds 0.5 sec dwell at the bottom
• Exits using feedrate, not rapid
• Used when surface finish is critical

---

🛑 G80 – Always Cancel After Use

Every canned cycle remains active until canceled. Before any rapid movement or tool change:

G80

This resets the modal cycle mode.

---

🧪 Example – Peck Drilling Multiple Holes

%
O6001 (G83 Peck Drilling)
G21 G90 G54
G0 Z5

G83 R2 Z-15 Q5 F120
X0 Y0
X20 Y0
X40 Y0

G80
G0 Z100
M30
%

---

🔍 Troubleshooting Canned Cycles

Problem	Cause	Fix
Hole not drilled fully	Too large Q value in G83	Use smaller peck (Q) value
Drill breaks	Feed too high or no chip break	Reduce F or use G83 with Q
Surface roughness	Rapid retraction from boring	Use G85 or G89 instead of G81
G-code errors	Forgetting to cancel with G80	Always insert G80 after cycles

---

💡 Pro Tips

• Use G83 for holes deeper than 3× drill diameter
• For aluminum or brass, G81 is often sufficient
• Set R-plane at least 1–2mm above the part surface
• Use P dwell values to improve tap bottom thread depth
• Always cancel with G80 before tool changes

---

🔚 Final Thoughts

Canned cycles like G81–G89 are powerful tools to simplify your code, reduce errors, and standardize hole machining.

Why write 10 lines of code for every hole when 1 will do?

Once mastered, canned cycles will drastically boost your productivity while reducing tool wear and crash risks.