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Feeds & speeds calculator for lathes and mills, drill size charts, and tap drill reference — all in one place. Bookmark it. Use it every day.

Feeds & Speeds Calculator
Lathe Inputs
Aluminum
Brass
Mild Steel
Alloy Steel
Stainless
Tool Steel
Cast Iron
Titanium
Inconel
Copper
Plastic
Custom
SFM
IN
IN/REV
IN
Lathe Results
Spindle Speed---RPM
Feed Rate---IN/MIN
Material Removal Rate---IN³/MIN
Surface Speed---SFM
Feed / Rev---IN/REV
Horsepower (est.)---HP
FORMULAS:
RPM = (SFM × 3.82) / Diameter
Feed Rate = RPM × Feed/Rev
MRR = Feed Rate × DOC × Dia
HP ≈ (MRR × Kc) / 396,000
TIPS:
› Reduce SFM 20-30% for interrupted cuts
› Stainless: sharp inserts & flood coolant
› Titanium: low SFM, higher feed/rev
› Inconel: slow SFM, rigid setup essential
Milling Inputs
Aluminum
Brass
Mild Steel
Alloy Steel
Stainless
Tool Steel
Cast Iron
Titanium
Inconel
Copper
Plastic
Custom
SFM
IN
FLUTES
IN/TOOTH
IN
IN
Milling Results
Spindle Speed---RPM
Feed Rate---IN/MIN
Chip Load / Tooth---IN/TOOTH
Material Removal Rate---IN³/MIN
Surface Speed---SFM
Horsepower (est.)---HP
FORMULAS:
RPM = (SFM × 3.82) / Cutter Dia
Feed Rate = RPM × Chip Load × Flutes
MRR = Feed Rate × ADOC × RDOC
HP ≈ (MRR × Kc) / 396,000
TIPS:
› Long reach: reduce feed 25-50%
› Climb mill for finish passes
› Thin walls: reduce RDOC, bump RPM
› Always verify max spindle RPM!
Drill Size Chart — Fractional, Number, Letter & Metric
Fractional
Number Drill
Letter Drill
Metric
Showing -- entries
Size Type Decimal (in) Decimal (mm) Closest Fraction
Tap Drill Chart — UN/UNF, Metric & Pipe Threads
UNC (Coarse)
UNF (Fine)
Metric
Pipe (NPT/NPTF)
Showing -- entries
Tap Size Type TPI / Pitch Tap Drill Drill Decimal (in) 75% Thread Clearance Drill
Roll Tap / Cold Form Tap Drill Chart — UN/UNF & Metric
WHAT IS COLD FORMING / ROLL TAPPING?
Roll taps (form taps) displace material instead of cutting it — producing stronger threads with no chips. The tap drill size is LARGER than a standard cut tap drill because the material flows inward to form threads rather than being removed. Use these sizes for blind holes in ductile materials: aluminum, brass, copper, mild steel, stainless, and titanium. NOT recommended for cast iron, hard steels, or brittle materials.
UNC (Coarse)
UNF (Fine)
Metric
Showing -- entries
Tap Size Type TPI / Pitch Roll Tap Drill Roll Drill Decimal (in) Cut Tap Drill (ref) Difference Material Notes
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