S7Shader7

CNC drilling and rigid tapping

Drill feed & RPM calculator

Choose your tool and material to calculate a practical spindle speed, feed rate, and ready-to-review canned cycle.

MetricRPM limitG81–G86
CNC drill machining a metal workpiece
Drilling & tapping setup
mm
Presets:
mm
mm
Cutting data & machine limit

Use your tool maker’s cutting data when available. Material presets are starting estimates. Tapping feed always follows thread pitch.

Calculated cutting data

Enter tool parameters, choose material, and click calculate to view optimal shop feeds, speeds, and depth warnings.

Sample CNC program

G-code program block will be generated here once parameters are calculated.

Cycle preview

Calculator parameters must be generated first. Click Calculate Parameters above to boot the VMC visualizer spindle.

Shop-Floor Technical Guides & Speeds/Feeds Equations

To achieve high-quality surface finishes and maximize cutting tool life, CNC machinists must calculate the exact spindle speed (RPM) and cutting feed rate (mm/min or inches/min). These parameters depend directly on the cutter diameter, cutting tool material (High-Speed Steel, Cobalt, or Solid Carbide), workpiece material density, and chip load guidelines.

The standard industrial mathematical formulas used inside this calculator are:

  • Spindle Speed (RPM): N = (V * 1000) / (pi * D), where N is Spindle Speed (RPM), V is Cutting Speed (m/min), and D is Tool Diameter (mm).
  • Feed Rate (F): F = N * f_rev, where F is Feed Rate (mm/min), N is Spindle Speed (RPM), and f_rev is Feed per Revolution (mm/rev).
  1. Select Operation: Choose either standard Drilling or Rigid Tapping from the operation dropdown.
  2. Enter Diameter: Input the nominal diameter of the drill bit or machine tap in millimeters.
  3. For Tapping: The calculator will suggest the standard metric coarse thread pitch (e.g., 1.0mm for M6, 1.5mm for M10). You can override this value for fine threads.
  4. Select Tool & Work Materials: HSS is ideal for soft steels and aluminum under conventional setups; Cobalt offers excellent heat tolerance for alloy steels; Solid Carbide represents the industry gold standard for high-rigidity high-speed production.
  5. Verify Peck Depth: If the drilling depth exceeds three times (3x) the drill diameter, a warning is displayed. CNC program blocks should use peck drilling cycles like G83 (deep-hole peck) or G73 (high-speed break-chip) to prevent tool failure.

Modern CNC machines (such as Haas, Fanuc, or Mazak controls) utilize Rigid Tapping cycles, represented by G-code G84. During rigid tapping, the spindle's rotation and the Z-axis linear feed are mechanically synchronized. The feed rate must satisfy the rigid ratio: Feed = Spindle Speed (RPM) * Thread Pitch.

Tapping uses feed per minute = programmed RPM × thread pitch. Decimal feeds are retained to preserve this relationship. The sample uses metric G94 feed mode and a Fanuc-style M29 rigid-tapping command; verify controller support.

Q: What happens if my feed rate is too high?

A: Excess feed rate causes the chip load to exceed the physical tooth capacity, resulting in immediate cutter breakage, chip packing, or severe structural deflection.

Q: Why does carbide require much higher cutting speeds (V)?

A: Solid carbide tools exhibit extreme red-hardness, retaining their structure at temperatures exceeding 900°C. This allows cutting speeds 3x to 4x higher than standard HSS.

Q: Do I need to use cutting fluid or coolant?

A: Yes, cutting fluid provides lubrication and cooling. For aluminum, it prevents the material from galling and welding to the flutes. For deep-hole steel drilling, high-pressure through-spindle coolant is recommended to flush chips upward.

Want to master drill size formulas, thread percentages, and Speeds & Feeds physics?

Speeds & Feeds Guide → Tap Drill Chart Reference →