KEVOS® MAKEOS · Gears
Involute Spline Basic Dimensions (ANSI B92.1)
What are the basic diameters and space width of this involute spline?
Pitch, base, major, minor and form diameters, circular pitch and minimum effective space width of 30° and 37.5° involute splines by the ANSI B92.1 basic formulas, for side-fit and major-diameter-fit variants.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Diametral pitch P (e.g. 16 for 16/32) | 1/in | Diametral pitch (the first number of the pitch fraction). |
| Number of teeth | teeth | Number of teeth. |
| Spline type | choice | Pressure angle, root form and fit. |
Method and formulas
- D = N/P; D_b = D cos φ; circular pitch = π/P; minimum effective space width = π/2P (30°) or (0.5π + 0.1)/P (37.5°).
- Major and minor diameters by fit type, e.g. 30° flat root side fit: D_ri = (N + 1.35)/P, D_o = (N + 1)/P, D_i = (N − 1)/P, D_re = (N − 1.35)/P.
- Form clearance c_F = 0.001D (0.002–0.010 in); form diameters D_Fi = (N + 1)/P + 2c_F, D_Fe = (N − 1)/P − 2c_F (major-fit and 37.5° variants differ).
- Example: 20 teeth at 16/32 pitch have D = 1.25 in and an external major diameter of 1.3125 in.
Limitations
- Basic dimensions only; tolerances, effective and actual space widths for each fit class come from the full standard.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Lay out a spline shaft and hub
- Check spline blanks before cutting
- Find form diameters for tool design
Who it is for
- Gear designers
- Machinists
- Maintenance engineers
What you get
- Pitch and base diameters
- Internal and external major and minor diameters
- Form diameters and form clearance
- Circular pitch and minimum effective space width
Interpreting the result
- Use the minimum effective space width with the standard’s tolerances to set gauge sizes.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2255–2282. Topic reference; no source tables or recommended settings are reproduced.
- ANSI B92.1 Involute Splines and Inspection
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Open the Involute Spline Basic Dimensions (ANSI B92.1) calculator
