CAM and Multi-Axis Deep Hole Drilling Strategies
For production deep hole drilling, CAM software provides toolpath strategies that optimize peck cycles, reduce cycle time, and handle complex multi-axis hole patterns that are impractical to program manually.
This guide covers CAM strategies for deep hole drilling, multi-axis positioning techniques, and subprogram methods for repeated deep hole patterns.
CAM Deep Hole Drilling Strategies
Peck Drill Toolpath (All CAM Systems)
All major CAM systems (Fusion 360, Mastercam, NX, SolidCAM, HSMWorks) provide a peck drill toolpath that generates optimized G83 code.
| CAM Parameter | What It Controls | Optimized Setting |
|---|---|---|
| Peck depth | Distance per peck | 50–75% of drill diameter for steel |
| Minimum peck | Smallest allowable peck | 1–2 mm (prevents friction burnishing) |
| Retract height | Height above hole bottom for retract | 0.5–1.0 mm (reduces cycle time) |
| Dwell | Pause at bottom (ms) | 200–500 ms for stainless, 0 for steel |
| Top offset | Extra clearance above part | 2–5 mm |
| Bottom offset | Drill tip beyond part (through-hole) | 1–2 mm |
Advanced CAM Strategies
| Strategy | How It Works | Benefit |
|---|---|---|
| Chip breaking (G73) | Short retract, no full chip clearance | Faster cycle time, limited to short-chip materials |
| Deep hole (G83) | Full retract each peck | Complete chip clearance, reliable |
| Custom peck pattern | Variable peck depths defined in CAM | Optimal at all depths |
| Fine peck (reduced at depth) | CAM automatically reduces peck depth | Prevents chip packing at deep sections |
| Pre-drill + finish | Two operation strategy | Better finish on deep holes |
Fusion 360 Deep Hole Drilling
Drilling Toolpath Settings
In Fusion 360, the Drilling toolpath provides deep hole parameters:
Drilling → Cycle Type → Peck / Deep Hole / Chip Breaking
Parameters:
- Cycle: Deep Hole (G83) or Chip Breaking (G73)
- Peck Depth: 3.0 mm
- Minimum Peck Depth: 1.0 mm (optional)
- Retract Height: 1.0 mm
- Dwell: 0.5 sec (optional)
- Tip Length: Include in hole depth
Fusion 360 Post-Processor Options
Fusion 360’s generic Fanuc post supports all standard cycles. Custom cycles require post-processor modification:
1// Post-processor modification for custom deep hole cycle
2if (cycleType == "peck") {
3 if (holeDepth > 40) {
4 // Use custom G123 for holes > 40mm
5 writeBlock("G123", ...);
6 } else {
7 // Standard G83 for shorter holes
8 writeBlock("G83", ...);
9 }
10}
Mastercam Deep Hole Drilling
Mastercam provides the most flexible deep hole drilling options in its Drill toolpath:
Toolpaths → Drill → Cycle Parameters:
- Drill Cycle: Peck Drill (G83)
- 1st Peck: 3.0 (first peck depth)
- Subsequent Peck: 2.5
- Peck Clearance: 0.5
- Retract Amount: 1.0
- Dwell: 0.0
- Chip Break: 0.0 (use 0.25 for G73)
Key feature: Mastercam supports different first peck depth and subsequent peck depth, addressing the common need for a deeper first engagement.
Multi-Axis Deep Hole Drilling
3+2 Positioning (Indexing)
For angled holes or holes on complex parts, 3+2 positioning (using a trunnion table or rotary axis) allows drilling at any angle:
; 3+2 indexing for an angled deep hole
; Rotary table at 30 degrees, tilt at 15 degrees
G00 G90 G54 A-30.0 B15.0
; Transform coordinate system
G68.2 X0 Y0 Z0 I-30.0 J15.0 K0.0
G53.1 ; Enable TCP (tool center point)
; Now drill a deep hole in the transformed plane
G99 G83 X0 Y0 Z-40.0 R2.0 Q4.0 F150
G80
G69 ; Cancel coordinate rotation
Full 5-Axis Deep Hole Drilling
For simultaneous 5-axis drilling (rare for deep holes, but used for complex entry angles):
; 5-axis simultaneous — drill while moving to maintain tool orientation
N100 G00 G90 G54 X0 Y0 Z50.0
N110 G43 H01 Z50.0
N120 #1=0
N130 WHILE [#1 GT -40.0] DO1
; Feed to peck depth while maintaining orientation
G01 Z[50.0 + #1] A[-30.0 + #1 * 0.75] F150
G00 Z50.0
#1=#1 - 4.0
G00 Z[50.0 + #1 + 0.5]
END1
Practical note: 5-axis deep hole drilling is slow and should be avoided. Use 3+2 positioning instead.
Angle Hole Best Practices
| Angle | Challenge | Solution |
|---|---|---|
| 0° (perpendicular) | Standard | No special handling |
| 15–30° from surface | Drill skids on initial contact | Spot drill first; use entry bushing |
| 30–60° | Increased tool deflection | Reduce feed 20–30%; use shorter drill |
| > 60° | Very difficult; drill tends to walk | Use a starting cutter; carbide stub drill |
Subprogram Technique for Repeated Deep Holes
For production parts with multiple deep holes at different positions, use a main program that calls a deep hole subprogram:
Main Program
O1000 (MAIN - DEEP HOLE PATTERN)
T1 M06
G90 G54 G00 X0 Y0
S2000 M03
G43 H01 Z50.0
M08
; Call deep hole subprogram for each position
X25.0 Y0 M98 P2000 (HOLE 1)
X50.0 Y0 M98 P2000 (HOLE 2)
X75.0 Y0 M98 P2000 (HOLE 3)
X100.0 Y0 M98 P2000 (HOLE 4)
G00 Z50.0
M09
M30
Subprogram
O2000 (DEEP HOLE SUB)
; Called at each position with G0 already at that XY
G91 ; Incremental mode
G99 G83 Z-40.0 R-48.0 Q4.0 F150 ; R = retract to Z2 (50-48)
G80 ; Cancel cycle
G90 ; Back to absolute
M99
CAM Post-Processor Customization
For production deep hole drilling, modifying the CAM post-processor to include deep hole logic saves programming time:
| Customization | Benefit |
|---|---|
| Automatic Q calculation | Post-processor selects Q based on drill diameter |
| Depth-dependent peck | Post-processor generates variable peck depths |
| Cycle type selection | Automatically chooses G73 vs G83 based on L/D |
| Multi-axis transformation | Corrects vector for 3+2 deep holes |
Comparison: CAM vs. Manual Programming
| Aspect | CAM Programming | Manual G-Code |
|---|---|---|
| Setup time | 5–15 min per part | 10–30 min per hole pattern |
| Optimization | Automatic peck calculation | Manual calculation |
| Multi-axis | Full support | Complex math required |
| Repeatability | Complete | Good for simple patterns |
| Custom cycles | Post-processor dependent | Full control via macros |
| Learning curve | Moderate | Low for simple; high for macros |
Summary
CAM software provides optimized deep hole drilling toolpaths that automatically calculate peck depths, retract heights, and cycle selection. For multi-axis parts, 3+2 positioning (indexing) is the preferred method for drilling angled deep holes; true 5-axis simultaneous drilling of deep holes is slow and should be avoided where possible. Subprogram techniques reduce program size and simplify editing when drilling many identical deep holes in a pattern. Customizing the CAM post-processor to include deep hole logic further streamlines programming for production environments.
For G83/G73 fundamentals, see CNC deep hole drilling G-code guide. For custom macro programming, see CNC macro programming guide. For a complete overview, visit the CNC deep hole drilling guide.