CNC Speeds & Feeds Calculator

Open Speeds & Feeds and the RPM and feed rate are already there: blank fields now use a starting chip load kept at or below a published slotting chart.

Speeds and feeds for CNC milling in one tap: pick a material and HSS or carbide, and the spindle RPM and feed rate appear straight away. Tap drill, bolt circle, taper and turning surface finish sit alongside, so the numbers a machinist reaches for all day are in one shop app that works offline, in inches or millimetres.

▶ SPEEDS & FEEDS • 8 workpiece materials: aluminum, brass, mild steel, alloy steel, stainless 304, cast iron, titanium and plastic • HSS or carbide tooling, with the starting cutting speed shown in SFM or m/min • Enter tool diameter, flute count and chip load (feed per tooth) to read spindle RPM and table feed in in/min or mm/min • Leave a field blank and the app fills in a starting value: a 10 mm (0.375 in) tool, 4 flutes and a suggested chip load kept at or below a published carbide end-mill slotting chart, so you see a result the moment you open it. Type your own numbers and they replace the suggestions • End-mill diagram shows the flute count and chip load per tooth for the setup on screen • Save up to 50 named presets and reload a whole setup in one tap

▶ TAP DRILL • Metric (20 sizes) and Unified UNC/UNF (33 sizes) threads • Thread engagement from 50% to 85% in 5% steps, 75% as the shop default • Theoretical tap-drill size plus the nearest standard drill

▶ BOLT CIRCLE • Hole count, circle diameter, start angle and centre X/Y give the X/Y coordinates of every hole, drawn to scale • Tap a row to copy its coordinates, or copy the whole table for the control

▶ TAPER & TURNING • Taper from two diameters and a length, or from an included angle, taper per foot or a 1:N ratio: compound-rest half-angle, included angle, taper per foot and per inch, in decimal degrees and degrees-minutes-seconds • Turning surface finish: theoretical Ra and Rt from feed per rev and nose radius, or the maximum feed for a target Ra

▶ REFERENCE • Cutting speed table by material for HSS and carbide • Drill size chart with 243 number, letter, fractional and metric sizes, searchable • Thread pitch and minor diameters, drill point depth and typical surface-finish ranges

All values are conservative starting points from published data, not guarantees. Always check against your tooling, machine and setup, start slow and increase.