Drilling Feeds & Speeds Calculator 2026
Calculate optimal drilling parameters for all materials and drill types. Get RPM, feed rates, peck depths, and G-code cycle recommendations for production-ready results.
Calculate Drilling Parameters
Drilling Feeds & Speeds: Complete Guide 2026
Proper drilling parameters are essential for achieving accurate holes, maximizing tool life, and preventing drill breakage. This guide covers everything from basic calculations to advanced techniques like peck drilling and through-tool coolant strategies.
Understanding Drilling Parameters
Cutting Speed (Vc)
The surface speed at the outer diameter of the drill, measured in m/min or SFM.
Formula: Vc = (π × D × n) / 1000
Feed Rate (f)
How far the drill advances per revolution, measured in mm/rev or IPR.
Rule of thumb: f = 0.015-0.025 × D for steel
Spindle Speed (n)
Rotational speed of the drill, measured in RPM.
Formula: n = (Vc × 1000) / (π × D)
L/D Ratio
Hole depth divided by drill diameter. Critical for peck drilling decisions.
Guidelines: >3 = Peck drilling recommended
When to Use Peck Drilling
Peck drilling (G83 cycle) retracts the drill periodically to clear chips. Use it when:
- Deep holes: L/D ratio greater than 3:1
- Gummy materials: Stainless steel, aluminum, titanium
- Chip problems: Stringy chips wrapping around drill
- No through-coolant: HSS drills without coolant-through
- Blind holes: To ensure clean bottoms
Peck Depth Guidelines
Drill Type Selection Guide
| Drill Type | Best For | Speed | Cost |
|---|---|---|---|
| HSS Twist | General purpose, low volume | 1× | $ |
| Cobalt HSS | Stainless steel, heat-resistant alloys | 1.3× | $$ |
| Solid Carbide | High-volume production, tight tolerance | 2.5× | $$$ |
| Coated Carbide | Maximum performance, difficult materials | 3× | $$$$ |
| Indexable | Large holes (>16mm), production | 3.5× | $$$$ |
| Gun Drill | Deep holes (L/D > 10) | 0.6× | $$$$$ |
Common Drilling Problems
❌ Drill Walking / Wandering
Causes: No pilot hole, split-point not used, workpiece not perpendicular.
Solutions: Spot drill first, use 135° split-point geometry, reduce initial speed.
❌ Drill Breakage
Causes: Chip packing, excessive feed, dull drill, misalignment.
Solutions: Use peck drilling, reduce feed, replace drill, check runout.
❌ Oversized Holes
Causes: Spindle runout, drill wobble, excessive speed, dull margins.
Solutions: Check holder runout (<0.02mm), reduce speed, resharpen or replace.
❌ Poor Surface Finish
Causes: Dull drill, improper coolant, excessive feed, chips re-cutting.
Solutions: Sharpen/replace drill, ensure coolant flow, reduce feed.
Frequently Asked Questions
For mild steel with HSS drills: 20-30 m/min (65-100 SFM). With cobalt HSS: 25-40 m/min. With coated carbide: 60-90 m/min. Always reduce speeds for deeper holes (reduce by 10% for each additional L/D ratio above 3). Stainless steel requires 40-50% lower speeds than mild steel.