Spline Dimensions: flat root
fr 6 12 to fr 8 24
Spline dimensions for three families: (1) ANSI B92.1-1970 (R1993)/1996 involute splines — flat root side fit, fillet root side fit, and major diameter fit, 30-degree pressure angle, diametral pitches 2.5/5 through 20/40; (2) ISO 14:1982/2004 straight-sided (parallel-sided) splines — light and medium series, 6/8/10 splines, metric mm; (3) DIN 5480-2:2015 metric involute splines — 30-degree pressure angle, modules m=2 and m=3, reference diameters 12–207 mm.
| spline type | record id | base circle dia in (in) | circular pitch in (in) | diametral pitch | fit class | major dia ext in (in) | major dia int in (in) | minor dia ext in (in) | minor dia int in (in) | module equiv (mm) | num teeth (count) | pitch dia in (in) | pitch dia mm (mm) | pressure angle deg (deg) | root type | standard | tooth thickness in (in) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| flat root | fr 6 12 | 1.7321 | 0.5236 | 6/12 | side fit | 2.1667 | 2.1667 | 1.75 | 1.8333 | 4.233 | 12 | 2 | 50.8 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.2618 |
| flat root | fr 6 15 | 2.1651 | 0.5236 | 6/12 | side fit | 2.6667 | 2.6667 | 2.25 | 2.3333 | 4.233 | 15 | 2.5 | 63.5 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.2618 |
| flat root | fr 6 20 | 2.8868 | 0.5236 | 6/12 | side fit | 3.5 | 3.5 | 3.0833 | 3.1667 | 4.233 | 20 | 3.3333 | 84.667 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.2618 |
| flat root | fr 6 24 | 3.4641 | 0.5236 | 6/12 | side fit | 4.1667 | 4.1667 | 3.75 | 3.8333 | 4.233 | 24 | 4 | 101.6 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.2618 |
| flat root | fr 8 12 | 1.299 | 0.3927 | 8/16 | side fit | 1.625 | 1.625 | 1.3125 | 1.375 | 3.175 | 12 | 1.5 | 38.1 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.1963 |
| flat root | fr 8 16 | 1.7321 | 0.3927 | 8/16 | side fit | 2.125 | 2.125 | 1.8125 | 1.875 | 3.175 | 16 | 2 | 50.8 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.1963 |
| flat root | fr 8 20 | 2.1651 | 0.3927 | 8/16 | side fit | 2.625 | 2.625 | 2.3125 | 2.375 | 3.175 | 20 | 2.5 | 63.5 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.1963 |
| flat root | fr 8 24 | 2.5981 | 0.3927 | 8/16 | side fit | 3.125 | 3.125 | 2.8125 | 2.875 | 3.175 | 24 | 3 | 76.2 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.1963 |
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