Threads, ANSI fits, drill sizes, tap drills, tapers, speeds & feeds, and shop geometry in one offline file.
Single-file HTML • Works offline • Imperial + metric helpersChoose a common UNC/UNF/UNS size or enter custom major diameter and TPI.
Basic geometry does not include thread class allowance/tolerance. For inspection limits, use the applicable ANSI/ASME table or Machinery's Handbook.
Exam-style fit lookup: enter a known shaft or hole size, choose the ANSI fit class, and calculate the required mating-part range from the standard clearance/interference limits.
ANSI B4.1 fit values are tabulated in thousandths of an inch. RC values are clearance; LN/FN values are interference; LT values are signed fit values where positive means clearance and negative means interference.
RC Running & sliding clearance fits. RC1 is tightest; RC9 is loosest.
LT Locational transition fits. Depending on actual sizes, the assembly can have slight clearance or slight interference.
LN Locational interference fits for accurate, rigid location.
FN Force & shrink fits. FN1 is light drive; FN5 is the heaviest class included.
LC locational-clearance classes are not embedded in this version. Use Machinery's Handbook / ANSI B4.1 for LC specifications.
This tool solves the common NIMS/Machinery's Handbook question style using a known finished shaft or hole dimension. For production drawings that specify independent basic-size hole and shaft tolerance zones, verify the complete ANSI B4.1 table.
Enter a target diameter and compare common fractional, number, and letter drills.
Fractional list uses 1/64-inch increments. Number and letter values match standard decimal equivalents represented on the Starrett decimal-equivalent card.
| Size | Type | Decimal (in) | Metric (mm) | Difference |
|---|
For a conical taper: enter large diameter, small diameter, and taper length.
Enter TPF and any two of D, d, and L; leave the dimension you want to solve blank.
The “half-angle” is the angle between the centerline and one tapered side—the angle commonly used when setting a lathe compound for a straight taper.
Choose the work material and cutting-tool material. The toolbox gives a practical starting SFM range, uses the midpoint as a starting value, and calculates RPM from your diameter.
Use the lower end of the range for a less rigid setup, harder material, interrupted cut, deeper cut, or when tool life matters more than production rate. Manufacturer data should override this general guide.
Use feed per revolution (IPR).
Use chip load per tooth and number of teeth/flutes.
Broad shop-planning ranges for common materials. These are deliberately general so they are useful for study and first-pass calculations rather than a substitute for a specific insert/end-mill/drill data sheet.
| Material | HSS SFM | Carbide SFM |
|---|
Speeds and feeds are planning values. Actual cutting data depends on material grade and hardness, tool coating and geometry, operation, coolant, machine rigidity, depth/width of cut, and tool manufacturer recommendations. Carbide values vary especially widely by grade and coating.
For a square machined concentrically from round stock, the square's diagonal equals the original round diameter.
RPM SFM × 3.82 ÷ diameter
SFM π × diameter × RPM ÷ 12
IPM RPM × IPR
Mill IPM RPM × chip load × teeth
TPI taper (big D − small d) ÷ length
TPF TPI taper × 12
Round → square D × 0.7071
Clearance fit hole = shaft + clearance
Interference fit hole = shaft − interference
These links are references for the formulas and chart data used in this toolbox. The calculator itself does not need internet access.
Omni Calculator — Taper Calculator
Kennametal — Speeds and Feeds Calculator
LittleMachineShop — Cutting Speed Reference by Operation & Material
WorkshopCalc — General HSS/Carbide Starting Ranges
Engineers Edge — Screw Thread Chart
ANSI B4.1 Shaft Fit Tables — RC / LT / LN / FN lookup data
Drill decimal and tap-drill lookup values: L.S. Starrett Decimal Equivalents, Bulletin 1317.