Spline Dimensions: flat root
fr 2.5 12 to fr 4 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 2.5 12 | 4.1569 | 1.2566 | 2.5/5 | side fit | 5.2 | 5.2 | 4.2 | 4.6 | 10.16 | 12 | 4.8 | 121.92 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.6283 |
| flat root | fr 2.5 16 | 5.5425 | 1.2566 | 2.5/5 | side fit | 6.8 | 6.8 | 5.8 | 6.2 | 10.16 | 16 | 6.4 | 162.56 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.6283 |
| flat root | fr 2.5 24 | 8.3138 | 1.2566 | 2.5/5 | side fit | 10 | 10 | 9 | 9.4 | 10.16 | 24 | 9.6 | 243.84 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.6283 |
| flat root | fr 20 13 | 0.5629 | 0.1571 | 20/40 | side fit | 0.7 | 0.7 | 0.575 | 0.6 | 1.27 | 13 | 0.65 | 16.51 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.0785 |
| flat root | fr 20 20 | 0.866 | 0.1571 | 20/40 | side fit | 1.05 | 1.05 | 0.925 | 0.95 | 1.27 | 20 | 1 | 25.4 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.0785 |
| flat root | fr 4 10 | 2.1651 | 0.7854 | 4/8 | side fit | 2.75 | 2.75 | 2.125 | 2.375 | 6.35 | 10 | 2.5 | 63.5 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.3927 |
| flat root | fr 4 12 | 2.5981 | 0.7854 | 4/8 | side fit | 3.25 | 3.25 | 2.625 | 2.875 | 6.35 | 12 | 3 | 76.2 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.3927 |
| flat root | fr 4 16 | 3.4641 | 0.7854 | 4/8 | side fit | 4.25 | 4.25 | 3.625 | 3.875 | 6.35 | 16 | 4 | 101.6 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.3927 |
| flat root | fr 4 20 | 4.3301 | 0.7854 | 4/8 | side fit | 5.25 | 5.25 | 4.625 | 4.875 | 6.35 | 20 | 5 | 127 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.3927 |
| flat root | fr 4 24 | 5.1962 | 0.7854 | 4/8 | side fit | 6.25 | 6.25 | 5.625 | 5.875 | 6.35 | 24 | 6 | 152.4 | 30 | flat | ANSI B92.1-1970 R1993 / Machinery's Handbook 31st Ed. | 0.3927 |
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