Learn CNC drilling cycles like G81, G82, G83 (peck drilling), and more. Includes syntax, Fanuc/Siemens/GRBL examples, cycle comparison charts, and safety tips.
Advanced G-Code Drilling Cycles Explained (G81–G89)
G-code drilling cycles automate repetitive operations like drilling, tapping, and boring. These “canned cycles” reduce program size and make complex hole-making faster and more efficient. Below is a detailed breakdown of each drilling cycle with real-world syntax, use cases, and control compatibility (Fanuc, Siemens, GRBL, LinuxCNC).
🧠 What Are Drilling Cycles (Canned Cycles)?
Drilling cycles allow a single G-code line to execute a full sequence of motions for a hole—approach, drill, retract. Commonly used cycles are G81 to G89.
🔍 G81 – Simple Drilling Cycle
| Syntax | G81 X__ Y__ Z__ R__ F__ |
|---|---|
| Description | Drills to depth Z at feedrate F, retracts to R-plane. |
| Example | G81 X20 Y30 Z-5 R2 F300 |
| Compatible Controllers | Fanuc, Siemens, GRBL*, Mach3 |
⏲️ G82 – Drilling with Dwell
| Syntax | G82 X__ Y__ Z__ R__ P__ F__ |
|---|---|
| New Parameter | P = dwell time in milliseconds |
| Example | G82 X20 Y30 Z-10 R2 P1000 F300 |
🪓 G83 – Peck Drilling (Deep Hole Drilling)
| Syntax | G83 X__ Y__ Z__ R__ Q__ F__ |
|---|---|
| Q | Peck depth per increment |
| Example | G83 X20 Y30 Z-20 R2 Q5 F200 |
| Behavior | Drills in steps of 5mm, retracting between each step |
📌 G84 – Tapping Cycle (Right-Hand)
Used with rigid tapping (requires spindle orientation and reverse).
G84 X10 Y10 Z-15 R1 F1.0📌 G85 – Boring Cycle (Feed In, Feed Out)
No dwell or pause; bores in and retracts smoothly.
G85 X20 Y40 Z-20 R2 F150📌 G86 to G89
Advanced boring cycles, each with unique retract/feed strategies (mostly Fanuc/Siemens). Not commonly used in hobby CNCs.
🧾 Comparison Table of Drilling Cycles
| Cycle | Action | Use Case | Special |
|---|---|---|---|
| G81 | Drill | Simple holes | None |
| G82 | Drill + Dwell | Brass, soft metals | Dwell pause |
| G83 | Peck drill | Deep holes | Chip clearing |
| G84 | Tap | Threading | Spindle sync |
| G85 | Bore | Smooth bores | No retract pause |
🔌 GRBL Compatibility Note
- GRBL v1.1 supports G81 (basic drilling)
- G83, G84, G85 are NOT natively supported in GRBL
- Use CAM software (like Fusion 360) to “post-process” pecking as separate G01 lines
🛠️ Toolpath Example – Multi-Hole Pattern with G81
G21 G90 G17
G0 Z5
G0 X10 Y10
G81 Z-8 R2 F250
X30 Y10
X50 Y10
X70 Y10
G80
G0 Z20
M30
Drills four holes along X-axis at Y=10mm. Use G80 to cancel the drilling cycle.
📐 Drilling Schematic (Visual Guide)
^ Z+
|
|
R--| ← Rapid to R-plane
|
| ← Feed into Z depth
Z
⚠️ Tips for Using Drilling Cycles Safely
- Always check tool length and Z-zero!
- Use dwell (G82) for gummy materials to avoid burrs
- Use coolant or air blast during peck drilling
- Don’t forget G80 to cancel active cycles!
📚 More Resources
Conclusion
Understanding and using G-code drilling cycles like G81–G89 can save massive time and improve hole quality in your CNC operations. For deeper knowledge and code libraries, explore more technical guides and download sample programs at cnccode.com.
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