# Roller chain sprocket dimensions (ANSI): pitch diameter, outside diameter, caliper and tooth width, #25 to #80, 9 to 60 teeth

> What is the pitch diameter, outside diameter and tooth width of a #40 (or #25, #35, #50, #60, #80) roller chain sprocket with N teeth?

- Category: Hardware › Bearings, rails & motion
- Kind: Standard part
- Basis: ANSI sprocket formulas as printed by Martin Sprocket, Machinery's Handbook and Gizmology, tooth width checked against Martin's table; computed per tooth count; maker CAD linked
- Page: https://xemstudio.com/objects/roller-chain-sprocket-dimensions-ansi/ · JSON: https://xemstudio.com/api/geometry?object=roller-chain-sprocket-dimensions-ansi · Plain text: https://xemstudio.com/objects/roller-chain-sprocket-dimensions-ansi/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- Formulas used for the table (all from the sources below; N = teeth, P = pitch, Dr = roller Ø): pitch Ø PD = P / sin(180° / N) (Martin, Gizmology); turned outside Ø OD = P × (0.6 + cot(180° / N)) (Martin, Machinery's Handbook, Gizmology); caliper Ø for an even tooth count = PD − Dr, for an odd count = PD × cos(90° / N) − Dr (Machinery's Handbook p. 1318; the page prints 'caliper factor = PD cos(90° ÷ N)'). Values are computed, not copied; PD of #40 with 20 teeth is 3.196 in (81.18 mm).
- OD is not critical to meshing (Martin): the table gives the turned OD above. Hob-cut and topped sprockets are a little different (OD = PD − Dr + 2 × the cutter's whole depth, Machinery's Handbook), and one forum tutorial uses OD = PD + P / 2; none of those figures are tabulated here, so check the maker's OD for a drawing. No source read gives a root-diameter formula, so none is tabulated; the caliper diameter is the practical check.
- Single-strand tooth width = 0.93 × inner width W − 0.006 in (Gizmology). It reproduces the first value of every row in Martin's single-strand tooth table for all six chains (#25 0.110, #35 0.168, #40 0.284, #50 0.343, #60 0.459, #80 0.575 in; #35 computes 0.169 against Martin's 0.168). Per-chain constants: #25: seat Ø Ds 0.1336 in (3.395 mm), seat radius R 0.0668 (1.697), working-curve radius E 0.1708 (4.339), ac 0.1040 (2.642), ab 0.1820 (4.623), single-strand tooth width 0.110 in (2.80 mm); #35: seat Ø Ds 0.2040 in (5.182 mm), seat radius R 0.1020 (2.591), working-curve radius E 0.2620 (6.655), ac 0.1600 (4.064), ab 0.2800 (7.112), single-strand tooth width 0.169 in (4.29 mm); #40: seat Ø Ds 0.3166 in (8.041 mm), seat radius R 0.1583 (4.020), working-curve radius E 0.4079 (10.360), ac 0.2496 (6.340), ab 0.4368 (11.095), single-strand tooth width 0.284 in (7.22 mm); #50: seat Ø Ds 0.4050 in (10.287 mm), seat radius R 0.2025 (5.143), working-curve radius E 0.5225 (13.271), ac 0.3200 (8.128), ab 0.5600 (14.224), single-strand tooth width 0.343 in (8.71 mm); #60: seat Ø Ds 0.4743 in (12.048 mm), seat radius R 0.2372 (6.024), working-curve radius E 0.6124 (15.554), ac 0.3752 (9.530), ab 0.6566 (16.678), single-strand tooth width 0.459 in (11.66 mm); #80: seat Ø Ds 0.6311 in (16.031 mm), seat radius R 0.3156 (8.015), working-curve radius E 0.8156 (20.715), ac 0.5000 (12.700), ab 0.8750 (22.225), single-strand tooth width 0.575 in (14.61 mm).
- ANSI B29.1 tooth-form constants read in the sources: seating-curve Ds = 1.005 Dr + 0.003 in (R = Ds / 2), working-curve radius E = 1.3025 Dr + 0.0015 in, G = 1.4 Dr (Machinery's Handbook p. 1330), seating angle A = 35° + 60° / N, B = 18° − 56° / N, ac = 0.8 Dr, ab = 1.4 Dr (Chief Delphi tutorial, which says the constants are from the ANSI standard). The remaining standard dimensions (chord yz, topping-curve radius F and offset H, S, W, V) could not be read from any source reachable here, so the full tooth outline is NOT drawn.
- No sprocket files: a tooth gap needs the whole ANSI outline, not just the seat arc, and the missing topping-curve numbers would have been invented. The existing roller-chain-sprockets page has #25 / #35 simplified-form files; its tooth form is labelled an approximation there. Martin says plate sprockets are normally made in sizes 7-1/2 in and larger, and type A (a plain plate with the tooth form and a bore) in all diameters; the plate thickness is the maker's choice.
- For a plate you intend to make yourself: use the PD, the seat Ø and the tooth width above, and cut the gaps with the maker's CAD (Tsubaki and Martin both offer it) or with the standard.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| roller seat Ø | Ds = 1.005 Dr + 0.003 in (#40: 0.316 in) | chain roller of Ø Dr (roller-chain-ansi-b29-1-25-to-80) | run | all |
| tooth width | 0.93 W − 0.006 in single strand (#40: 0.284 in) | chain inner width W between inner plates | run | all |

## Sizes

| chain | teeth N | pitch Ø PD, in | pitch Ø PD, mm | turned OD, in | turned OD, mm | caliper Ø, in | caliper Ø, mm |
|---|---|---|---|---|---|---|---|
| #25 | 9 | 0.731 | 18.57 | 0.837 | 21.26 | 0.590 | 14.98 |
| #25 | 10 | 0.809 | 20.55 | 0.919 | 23.35 | 0.679 | 17.25 |
| #25 | 11 | 0.887 | 22.54 | 1.001 | 25.44 | 0.748 | 19.01 |
| #25 | 12 | 0.966 | 24.53 | 1.083 | 27.51 | 0.836 | 21.23 |
| #25 | 13 | 1.045 | 26.53 | 1.164 | 29.57 | 0.907 | 23.04 |
| #25 | 14 | 1.123 | 28.54 | 1.245 | 31.63 | 0.993 | 25.23 |
| #25 | 15 | 1.202 | 30.54 | 1.326 | 33.68 | 1.066 | 27.07 |
| #25 | 16 | 1.281 | 32.55 | 1.407 | 35.73 | 1.151 | 29.25 |
| #25 | 17 | 1.361 | 34.56 | 1.487 | 37.78 | 1.225 | 31.11 |
| #25 | 18 | 1.440 | 36.57 | 1.568 | 39.82 | 1.310 | 33.27 |
| #25 | 19 | 1.519 | 38.58 | 1.648 | 41.86 | 1.384 | 35.15 |
| #25 | 20 | 1.598 | 40.59 | 1.728 | 43.90 | 1.468 | 37.29 |
| #25 | 21 | 1.677 | 42.61 | 1.809 | 45.94 | 1.543 | 39.18 |
| #25 | 22 | 1.757 | 44.62 | 1.889 | 47.98 | 1.627 | 41.32 |
| #25 | 23 | 1.836 | 46.63 | 1.969 | 50.01 | 1.702 | 43.22 |
| #25 | 24 | 1.915 | 48.65 | 2.049 | 52.04 | 1.785 | 45.35 |
| #25 | 25 | 1.995 | 50.66 | 2.129 | 54.08 | 1.861 | 47.26 |
| #25 | 28 | 2.233 | 56.71 | 2.369 | 60.17 | 2.103 | 53.41 |
| #25 | 30 | 2.392 | 60.75 | 2.529 | 64.23 | 2.262 | 57.45 |
| #25 | 32 | 2.551 | 64.78 | 2.688 | 68.28 | 2.421 | 61.48 |
| #25 | 35 | 2.789 | 70.84 | 2.928 | 74.36 | 2.656 | 67.47 |
| #25 | 36 | 2.868 | 72.86 | 3.008 | 76.39 | 2.738 | 69.56 |
| #25 | 40 | 3.186 | 80.93 | 3.327 | 84.49 | 3.056 | 77.63 |
| #25 | 45 | 3.584 | 91.03 | 3.725 | 94.62 | 3.452 | 87.67 |
| #25 | 48 | 3.822 | 97.09 | 3.964 | 100.69 | 3.692 | 93.79 |
| #25 | 50 | 3.981 | 101.13 | 4.124 | 104.74 | 3.851 | 97.83 |
| #25 | 60 | 4.777 | 121.33 | 4.920 | 124.98 | 4.647 | 118.03 |
| #35 | 9 | 1.096 | 27.85 | 1.255 | 31.88 | 0.880 | 22.35 |
| #35 | 10 | 1.214 | 30.82 | 1.379 | 35.03 | 1.014 | 25.74 |
| #35 | 11 | 1.331 | 33.81 | 1.502 | 38.15 | 1.118 | 28.38 |
| #35 | 12 | 1.449 | 36.80 | 1.625 | 41.26 | 1.249 | 31.72 |
| #35 | 13 | 1.567 | 39.80 | 1.746 | 44.36 | 1.356 | 34.43 |
| #35 | 14 | 1.685 | 42.80 | 1.868 | 47.45 | 1.485 | 37.72 |
| #35 | 15 | 1.804 | 45.81 | 1.989 | 50.53 | 1.594 | 40.48 |
| #35 | 16 | 1.922 | 48.82 | 2.110 | 53.60 | 1.722 | 43.74 |
| #35 | 17 | 2.041 | 51.84 | 2.231 | 56.67 | 1.832 | 46.54 |
| #35 | 18 | 2.160 | 54.85 | 2.352 | 59.73 | 1.960 | 49.77 |
| #35 | 19 | 2.278 | 57.87 | 2.472 | 62.80 | 2.071 | 52.59 |
| #35 | 20 | 2.397 | 60.89 | 2.593 | 65.85 | 2.197 | 55.81 |
| #35 | 21 | 2.516 | 63.91 | 2.713 | 68.91 | 2.309 | 58.65 |
| #35 | 22 | 2.635 | 66.93 | 2.833 | 71.96 | 2.435 | 61.85 |
| #35 | 23 | 2.754 | 69.95 | 2.953 | 75.01 | 2.548 | 64.71 |
| #35 | 24 | 2.873 | 72.97 | 3.073 | 78.06 | 2.673 | 67.89 |
| #35 | 25 | 2.992 | 76.00 | 3.193 | 81.11 | 2.786 | 70.77 |
| #35 | 28 | 3.349 | 85.07 | 3.553 | 90.25 | 3.149 | 79.99 |
| #35 | 30 | 3.588 | 91.12 | 3.793 | 96.34 | 3.388 | 86.04 |
| #35 | 32 | 3.826 | 97.18 | 4.032 | 102.42 | 3.626 | 92.10 |
| #35 | 35 | 4.183 | 106.26 | 4.392 | 111.55 | 3.979 | 101.07 |
| #35 | 36 | 4.303 | 109.29 | 4.511 | 114.59 | 4.103 | 104.21 |
| #35 | 40 | 4.780 | 121.40 | 4.990 | 126.74 | 4.580 | 116.32 |
| #35 | 45 | 5.376 | 136.55 | 5.588 | 141.93 | 5.173 | 131.38 |
| #35 | 48 | 5.734 | 145.64 | 5.946 | 151.04 | 5.534 | 140.56 |
| #35 | 50 | 5.972 | 151.69 | 6.185 | 157.11 | 5.772 | 146.61 |
| #35 | 60 | 7.165 | 182.00 | 7.380 | 187.46 | 6.965 | 176.92 |
| #40 | 9 | 1.462 | 37.13 | 1.674 | 42.51 | 1.128 | 28.64 |
| #40 | 10 | 1.618 | 41.10 | 1.839 | 46.71 | 1.306 | 33.17 |
| #40 | 11 | 1.775 | 45.08 | 2.003 | 50.87 | 1.445 | 36.69 |
| #40 | 12 | 1.932 | 49.07 | 2.166 | 55.02 | 1.620 | 41.14 |
| #40 | 13 | 2.089 | 53.07 | 2.329 | 59.15 | 1.762 | 44.76 |
| #40 | 14 | 2.247 | 57.07 | 2.491 | 63.26 | 1.935 | 49.15 |
| #40 | 15 | 2.405 | 61.08 | 2.652 | 67.37 | 2.080 | 52.82 |
| #40 | 16 | 2.563 | 65.10 | 2.814 | 71.47 | 2.251 | 57.17 |
| #40 | 17 | 2.721 | 69.12 | 2.975 | 75.56 | 2.397 | 60.90 |
| #40 | 18 | 2.879 | 73.14 | 3.136 | 79.65 | 2.567 | 65.21 |
| #40 | 19 | 3.038 | 77.16 | 3.296 | 83.73 | 2.715 | 68.97 |
| #40 | 20 | 3.196 | 81.18 | 3.457 | 87.80 | 2.884 | 73.26 |
| #40 | 21 | 3.355 | 85.21 | 3.617 | 91.88 | 3.033 | 77.05 |
| #40 | 22 | 3.513 | 89.24 | 3.778 | 95.95 | 3.201 | 81.31 |
| #40 | 23 | 3.672 | 93.27 | 3.938 | 100.02 | 3.351 | 85.13 |
| #40 | 24 | 3.831 | 97.30 | 4.098 | 104.09 | 3.519 | 89.37 |
| #40 | 25 | 3.989 | 101.33 | 4.258 | 108.15 | 3.669 | 93.21 |
| #40 | 28 | 4.466 | 113.43 | 4.738 | 120.34 | 4.154 | 105.50 |
| #40 | 30 | 4.783 | 121.50 | 5.057 | 128.45 | 4.471 | 113.57 |
| #40 | 32 | 5.101 | 129.57 | 5.377 | 136.57 | 4.789 | 121.64 |
| #40 | 35 | 5.578 | 141.68 | 5.855 | 148.73 | 5.260 | 133.61 |
| #40 | 36 | 5.737 | 145.72 | 6.015 | 152.78 | 5.425 | 137.79 |
| #40 | 40 | 6.373 | 161.87 | 6.653 | 168.99 | 6.061 | 153.94 |
| #40 | 45 | 7.168 | 182.06 | 7.450 | 189.24 | 6.851 | 174.03 |
| #40 | 48 | 7.645 | 194.18 | 7.929 | 201.38 | 7.333 | 186.26 |
| #40 | 50 | 7.963 | 202.26 | 8.247 | 209.48 | 7.651 | 194.34 |
| #40 | 60 | 9.554 | 242.66 | 9.841 | 249.95 | 9.242 | 234.74 |
| #50 | 9 | 1.827 | 46.42 | 2.092 | 53.14 | 1.400 | 35.55 |
| #50 | 10 | 2.023 | 51.37 | 2.299 | 58.38 | 1.623 | 41.21 |
| #50 | 11 | 2.218 | 56.35 | 2.504 | 63.59 | 1.796 | 45.61 |
| #50 | 12 | 2.415 | 61.34 | 2.708 | 68.77 | 2.015 | 51.18 |
| #50 | 13 | 2.612 | 66.33 | 2.911 | 73.93 | 2.193 | 55.69 |
| #50 | 14 | 2.809 | 71.34 | 3.113 | 79.08 | 2.409 | 61.18 |
| #50 | 15 | 3.006 | 76.35 | 3.315 | 84.21 | 2.590 | 65.78 |
| #50 | 16 | 3.204 | 81.37 | 3.517 | 89.33 | 2.804 | 71.21 |
| #50 | 17 | 3.401 | 86.39 | 3.718 | 94.45 | 2.987 | 75.87 |
| #50 | 18 | 3.599 | 91.42 | 3.920 | 99.56 | 3.199 | 81.26 |
| #50 | 19 | 3.797 | 96.45 | 4.120 | 104.66 | 3.384 | 85.96 |
| #50 | 20 | 3.995 | 101.48 | 4.321 | 109.76 | 3.595 | 91.32 |
| #50 | 21 | 4.193 | 106.51 | 4.522 | 114.85 | 3.782 | 96.06 |
| #50 | 22 | 4.392 | 111.55 | 4.722 | 119.94 | 3.992 | 101.39 |
| #50 | 23 | 4.590 | 116.59 | 4.922 | 125.02 | 4.179 | 106.15 |
| #50 | 24 | 4.788 | 121.62 | 5.122 | 130.11 | 4.388 | 111.46 |
| #50 | 25 | 4.987 | 126.66 | 5.322 | 135.19 | 4.577 | 116.25 |
| #50 | 28 | 5.582 | 141.79 | 5.922 | 150.42 | 5.182 | 131.63 |
| #50 | 30 | 5.979 | 151.87 | 6.321 | 160.57 | 5.579 | 141.71 |
| #50 | 32 | 6.376 | 161.96 | 6.721 | 170.71 | 5.976 | 151.80 |
| #50 | 35 | 6.972 | 177.10 | 7.319 | 185.91 | 6.565 | 166.76 |
| #50 | 36 | 7.171 | 182.15 | 7.519 | 190.98 | 6.771 | 171.99 |
| #50 | 40 | 7.966 | 202.33 | 8.316 | 211.24 | 7.566 | 192.17 |
| #50 | 45 | 8.960 | 227.58 | 9.313 | 236.55 | 8.554 | 217.28 |
| #50 | 48 | 9.556 | 242.73 | 9.911 | 251.73 | 9.156 | 232.57 |
| #50 | 50 | 9.954 | 252.82 | 10.309 | 261.85 | 9.554 | 242.66 |
| #50 | 60 | 11.942 | 303.33 | 12.301 | 312.44 | 11.542 | 293.17 |
| #60 | 9 | 2.193 | 55.70 | 2.511 | 63.77 | 1.691 | 42.94 |
| #60 | 10 | 2.427 | 61.65 | 2.758 | 70.06 | 1.958 | 49.73 |
| #60 | 11 | 2.662 | 67.62 | 3.004 | 76.31 | 2.166 | 55.02 |
| #60 | 12 | 2.898 | 73.60 | 3.249 | 82.53 | 2.429 | 61.69 |
| #60 | 13 | 3.134 | 79.60 | 3.493 | 88.72 | 2.642 | 67.11 |
| #60 | 14 | 3.370 | 85.61 | 3.736 | 94.89 | 2.901 | 73.70 |
| #60 | 15 | 3.607 | 91.63 | 3.978 | 101.05 | 3.119 | 79.21 |
| #60 | 16 | 3.844 | 97.65 | 4.221 | 107.20 | 3.375 | 85.73 |
| #60 | 17 | 4.082 | 103.67 | 4.462 | 113.34 | 3.595 | 91.32 |
| #60 | 18 | 4.319 | 109.70 | 4.703 | 119.47 | 3.850 | 97.79 |
| #60 | 19 | 4.557 | 115.74 | 4.945 | 125.59 | 4.072 | 103.43 |
| #60 | 20 | 4.794 | 121.78 | 5.185 | 131.71 | 4.325 | 109.86 |
| #60 | 21 | 5.032 | 127.82 | 5.426 | 137.82 | 4.549 | 115.55 |
| #60 | 22 | 5.270 | 133.86 | 5.666 | 143.93 | 4.801 | 121.95 |
| #60 | 23 | 5.508 | 139.90 | 5.907 | 150.03 | 5.026 | 127.66 |
| #60 | 24 | 5.746 | 145.95 | 6.147 | 156.13 | 5.277 | 134.04 |
| #60 | 25 | 5.984 | 151.99 | 6.387 | 162.23 | 5.503 | 139.78 |
| #60 | 28 | 6.699 | 170.14 | 7.106 | 180.50 | 6.230 | 158.23 |
| #60 | 30 | 7.175 | 182.25 | 7.586 | 192.68 | 6.706 | 170.33 |
| #60 | 32 | 7.652 | 194.35 | 8.065 | 204.85 | 7.183 | 182.44 |
| #60 | 35 | 8.367 | 212.52 | 8.783 | 223.09 | 7.889 | 200.39 |
| #60 | 36 | 8.605 | 218.57 | 9.023 | 229.17 | 8.136 | 206.66 |
| #60 | 40 | 9.559 | 242.80 | 9.980 | 253.48 | 9.090 | 230.89 |
| #60 | 45 | 10.752 | 273.09 | 11.175 | 283.86 | 10.276 | 261.01 |
| #60 | 48 | 11.467 | 291.27 | 11.893 | 302.08 | 10.998 | 279.36 |
| #60 | 50 | 11.944 | 303.39 | 12.371 | 314.22 | 11.475 | 291.48 |
| #60 | 60 | 14.330 | 363.99 | 14.761 | 374.93 | 13.861 | 352.08 |
| #80 | 9 | 2.924 | 74.26 | 3.347 | 85.03 | 2.254 | 57.26 |
| #80 | 10 | 3.236 | 82.20 | 3.678 | 93.41 | 2.611 | 66.32 |
| #80 | 11 | 3.549 | 90.16 | 4.006 | 101.74 | 2.888 | 73.36 |
| #80 | 12 | 3.864 | 98.14 | 4.332 | 110.03 | 3.239 | 82.26 |
| #80 | 13 | 4.179 | 106.14 | 4.657 | 118.29 | 3.523 | 89.49 |
| #80 | 14 | 4.494 | 114.15 | 4.981 | 126.52 | 3.869 | 98.27 |
| #80 | 15 | 4.810 | 122.17 | 5.305 | 134.74 | 4.158 | 105.62 |
| #80 | 16 | 5.126 | 130.20 | 5.627 | 142.93 | 4.501 | 114.32 |
| #80 | 17 | 5.442 | 138.23 | 5.950 | 151.12 | 4.794 | 121.77 |
| #80 | 18 | 5.759 | 146.27 | 6.271 | 159.29 | 5.134 | 130.40 |
| #80 | 19 | 6.076 | 154.32 | 6.593 | 167.45 | 5.430 | 137.92 |
| #80 | 20 | 6.392 | 162.37 | 6.914 | 175.61 | 5.767 | 146.49 |
| #80 | 21 | 6.710 | 170.42 | 7.235 | 183.76 | 6.066 | 154.07 |
| #80 | 22 | 7.027 | 178.48 | 7.555 | 191.90 | 6.402 | 162.60 |
| #80 | 23 | 7.344 | 186.54 | 7.876 | 200.04 | 6.702 | 170.23 |
| #80 | 24 | 7.661 | 194.60 | 8.196 | 208.17 | 7.036 | 178.72 |
| #80 | 25 | 7.979 | 202.66 | 8.516 | 216.30 | 7.338 | 186.38 |
| #80 | 28 | 8.931 | 226.86 | 9.475 | 240.67 | 8.306 | 210.98 |
| #80 | 30 | 9.567 | 243.00 | 10.114 | 256.90 | 8.942 | 227.12 |
| #80 | 32 | 10.202 | 259.14 | 10.753 | 273.13 | 9.577 | 243.26 |
| #80 | 35 | 11.156 | 283.36 | 11.711 | 297.46 | 10.520 | 267.20 |
| #80 | 36 | 11.474 | 291.43 | 12.030 | 305.56 | 10.849 | 275.56 |
| #80 | 40 | 12.745 | 323.74 | 13.306 | 337.98 | 12.120 | 307.86 |
| #80 | 45 | 14.336 | 364.12 | 14.901 | 378.48 | 13.702 | 348.03 |
| #80 | 48 | 15.290 | 388.36 | 15.857 | 402.77 | 14.665 | 372.49 |
| #80 | 50 | 15.926 | 404.52 | 16.495 | 418.96 | 15.301 | 388.64 |
| #80 | 60 | 19.107 | 485.33 | 19.681 | 499.90 | 18.482 | 469.45 |

## Where the files are

- Martin Sprocket: [Sprocket engineering data: PD = pitch / sin(180 / N), OD = pitch (0.6 + cot(180 / N)), roller width and diameter, single-strand tooth width table](https://www.martinsprocket.com/docs/catalogs/engineering/engineering%20catalog/sprocket-engineering-data.pdf) — web — Publisher's page; dimensions are facts
- Machinery's Handbook, 31st ed.: [Transmission roller chains: caliper diameter (PD cos(90 / N) − Dr for odd teeth), turned OD formula, working curve E = 1.3025 Dr + 0.0015 in, G = 1.4 Dr](https://online.flippingbook.com/view/954046886/1318) — web — Publisher's page; dimensions are facts
- Machinery's Handbook, 31st ed.: [Transmission roller chains, hob layout page: E and G for all ranges](https://online.flippingbook.com/view/954046886/1330) — web — Publisher's page; dimensions are facts
- Chief Delphi (forum tutorial): [Sprocket design tutorial: ANSI constants A = 35° + 60° / n, B = 18° − 56° / n, R = Ds / 2, Ds = 1.005 Dr + 0.003 in, ac = 0.8 Dr, ab = 1.4 Dr](https://www.chiefdelphi.com/t/sprocket-design-tutorial/387449) — web — Publisher's page; dimensions are facts
- Gizmology (notes quoted on meslab.org): [Notes on sprockets and chains: PD, OD and sprocket thickness = 0.93 × roller width − 0.006 in](https://meslab.org/goto/post?id=71581) — web — Publisher's page; dimensions are facts
- ASME: [ASME B29.1-2011 Precision power transmission roller chains, attachments, and sprockets (the standard itself, paid)](https://webstore.ansi.org/standards/asme/asmeb292011r2022) — web — Publisher's page; dimensions are facts
- Tsubaki (US): [Roller chain, sprockets and TAPER-LOCK bushings: maker catalogue with CAD downloads](https://www.tsubaki.com/) — web — Publisher's page; dimensions are facts
- Martin Sprocket: [Martin Sprocket & Gear CAD library (sprockets, QD and taper bushings)](https://www.martinsprocket.com/) — web — Publisher's page; dimensions are facts

## Questions

**What is the pitch diameter of a 20 tooth #40 sprocket?**

3.196 in (81.18 mm): PD = 0.5 in / sin(9°). Its turned OD is 3.457 in (87.8 mm).

**What is the tooth width of a #40 sprocket?**

0.284 in (7.2 mm) for a single strand: 0.93 × 0.312 in − 0.006 in, the same as Martin's table.

**How do I measure an odd-tooth sprocket?**

Over the nearly opposite tooth spaces: caliper Ø = PD × cos(90° / N) − roller Ø; for even tooth counts it is PD − roller Ø.

**Is the sprocket seat radius the same as the roller radius?**

No: the seat diameter is 1.005 × roller Ø + 0.003 in, so the roller sits in a seat a few thousandths larger.

## Fits with

- [Roller chain sprockets: #25 (6.35 mm) and #35 (9.525 mm), 10–40 T](https://xemstudio.com/objects/roller-chain-sprockets/)
- [Roller chain ANSI B29.1 #25, #35, #40, #50, #60, #80: pitch, roller diameter, inner width, pin, plate height](https://xemstudio.com/objects/roller-chain-ansi-b29-1-25-to-80/)
- [Taper-Lock bushings 1008 to 5050: bore range, length through bore, set screw and cap screw sizes](https://xemstudio.com/objects/taper-lock-bushings-1008-to-5050/)
- [QD bushings SH, SDS, SD: length, bolt circle, flange diameter and cap screws](https://xemstudio.com/objects/qd-bushings-sh-sds-sd/)
- [Parallel keys DIN 6885 form A: 2 × 2 to 18 × 11, with keyway depths](https://xemstudio.com/objects/parallel-keys-din-6885/)
- [Square keys, inch (ANSI B17.1): 3/32 to 1/2 in](https://xemstudio.com/objects/square-keys-inch/)
- [Metric shafts Ø3 to Ø10 with D-flats and clip grooves](https://xemstudio.com/objects/metric-shafts/)