Drilling
Creating holes using the tailstock
Process Steps
1. Center Drilling
Start with center drill to establish precise starting point.
2. Pilot Drilling
For larger holes, start with smaller pilot drill.
3. Progressive Drilling
Drill to full size, withdrawing regularly to clear chips.
4. Depth Control
Use tailstock quill graduations or depth stop for precise depth.
5. Final Verification
Check hole size, depth, and straightness.
Material-Specific Guidelines
Mild Steel
- • Good drilling characteristics
- • Continuous chips require regular withdrawal
- • Standard cutting fluids effective
Recommended Speeds: 70-90 SFPM for HSS drills, 150-200 SFPM for carbide
Tooling Notes: Standard 118° point angle works well
Stainless Steel
- • Work hardening tendency
- • Higher thrust forces needed
- • Heat buildup common
Recommended Speeds: 30-40 SFPM for HSS drills, 80-120 SFPM for carbide
Tooling Notes: 135° point angle recommended, heavy-duty drills preferred
Cast Iron
- • Excellent drilling properties
- • Dry cutting possible
- • Abrasive nature affects tool life
Recommended Speeds: 50-60 SFPM for HSS drills, 150-200 SFPM for carbide
Tooling Notes: 118° point angle, harder drill grades recommended
Quality Control Specifications
Hole Diameter
Method: Pin gauges or inside micrometer
Tolerance: ±0.002" typical
Frequency: First piece and periodic
Hole Depth
Method: Depth micrometer or depth gauge
Tolerance: ±0.005" typical
Frequency: Every hole
Hole Straightness
Method: Long pin gauge or bore scope
Tolerance: 0.002" per inch typical
Frequency: Sample basis
Surface Finish
Method: Visual and bore gauge feel
Tolerance: 125-250 microinch typical
Frequency: Every hole
Operation Difficulty
Basic
Safety Guidelines
- • Always use a center drill before regular drilling
- • Ensure drill is properly secured in tailstock chuck
- • Clear chips frequently, especially with deep holes
- • Use appropriate cutting speeds for material
- • Apply cutting fluid when necessary
Required Tooling
Center Drills
For starting holes and protecting larger drills
Twist Drills
Various sizes for different hole requirements
Tailstock Chuck
For holding drilling tools securely
Drill Gauge
For checking drill sizes and conditions
Troubleshooting Guide
Drill Wandering
Always start with properly ground center drill, ensure rigid setup
Oversized Holes
Check for drill runout, verify speed and feed rates, use drill bushings if needed
Poor Surface Finish
Verify cutting fluid flow, check drill condition, adjust speed/feed
Drill Breakage
Clear chips more frequently, reduce feed pressure, verify proper point angle
Tapered Holes
Check tailstock alignment, ensure proper drill grinding, use shorter drills
Pro Tips & Tricks
Center Drilling
Always start with proper center drill. Match center drill size to drill diameter.
Best for: All precision drilling operations
Peck Drilling
Withdraw drill regularly: 1× diameter for shallow, more frequent for deep holes.
Best for: Holes deeper than 3× diameter
Speed Calculation
RPM = (CS × 4) ÷ D, where CS is cutting speed and D is drill diameter. Reduce 20% for harder materials.
Best for: All drilling operations
Deep Hole Technique
Start with short drill for accuracy, then switch to longer drill. Use high-pressure coolant.
Best for: Holes deeper than 5× diameter