Select screw size, get recommended countersink diameter and angle automatically
Screw Size
M2
M3
M4
M5
M6
M8
M10
M12
M16
M20
Screw Head Angle
60° (Special countersink / locating)
82° (Imperial ANSI)
90° (Metric GB)
100° (Aerospace MS)
110° (Some imperial)
120° (Thin sheet / large flat head)
Recommended Tool Diameter
Ø14 mm
Countersink Diameter
Ø10.0 mm
Angle Reference
Angle
Standard
Applications
90°
Metric GB/T 819
Most common, sheet metal, enclosures, machinery
82°
Imperial ANSI B18.6.3
Export products, ANSI equipment
100°
Aerospace MS24694
Aerospace, military
120°
Large flat head / special countersink
Thin sheets, decorative panels
60°
Special tapered / locating holes
Special tooling, locating
110°
Some imperial
Imperial equipment, imported machinery
Diameter Reference
Screw Size
Recommended Tool Diameter
Countersink Diameter
Pilot Hole Diameter
M3 Ø8 Ø5.5 Ø3.2 M4 Ø10 Ø7.0 Ø4.3 M5 Ø12 Ø8.5 Ø5.3 M6 Ø14 Ø10.0 Ø6.4 M8 Ø16-Ø20 Ø13.0 Ø8.4 M10 Ø20-Ø25 Ø16.0 Ø10.5 M12 Ø25-Ø30 Ø18.0 Ø13.0
Recommended tool diameter is 2-3mm larger than the countersink hole to avoid edge contact. Custom sizes delivered in 7 days, MOQ 10 pcs.
Enter tool diameter and material to auto-calculate speed and feed (based on professional cutting data)
Tool Diameter (mm)
Workpiece Material
Low-carbon steel (<800 N/mm²)
Medium-carbon steel (800-1200 N/mm²)
Alloy steel
Stainless steel
Hardened steel (>1200 N/mm²)
Cast iron
Aluminum alloy
Brass
Bronze
Copper
Plastic / Acrylic
Tool Material
Cobalt HSS (Lihao standard)
Cobalt HSS + TiN coating
Cobalt HSS + TiAlN nano coating
Carbide
Cutting Speed Vc
30 m/min
Feed per Revolution
0.05 mm/rev
⚠️ Important Notes
• These are starting points - always test cut first!
• Better machine, higher speed : a machining center with good rigidity and cooling can run 2-3x faster than a bench drill
• Bigger hole, lower speed : with constant linear speed, larger tool = lower RPM
• Harder material, lower speed : reduce speed for stainless and hardened steel
• Example: 4mm pilot hole in stainless with Ø12×90° countersink: ~400 RPM on bench drill , 1000+ RPM on machining center
📊 Cutting Speed Vc Reference (m/min)
Workpiece Material
HSS-Co
+TiN
+TiAlN
Carbide
Low-carbon steel 30-40 40-60 60-100 100-200 Medium-carbon steel 20-30 30-50 50-80 80-150 Alloy steel 15-25 25-40 40-60 60-120 Stainless steel 10-15 15-25 25-40 40-80 Hardened steel 6-10 10-15 15-25 25-50 Cast iron 25-40 40-60 60-100 100-200 Aluminum alloy 150-300 200-400 300-600 500-1000 Brass 80-150 100-200 150-300 300-500 Plastic 100-200 150-300 200-400 300-600
Vc = cutting speed (m/min), RPM = Vc × 1000 ÷ (π × tool diameter)
Four dimensions, know three to get the fourth - fill in any three
Fill three values, the fourth is calculated automatically
