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

sizes

162 in table

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.

Roller chain sprocket dimensions (ANSI): pitch diameter, outside… size chart

Mating features

Drawn at the exact size. Open press, slide, run and socket features by your process's clearance (tolerances by process); leave designed gaps and clamp fits as drawn.

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Xem scan

File coming

No downloadable true-size file yet: the published figures do not fix the whole shape, and Xem never guesses a number. A measured scan is planned; request it and it moves up.

Plain text: sheet.txt · JSON: /api/geometry?object=roller-chain-sprocket-dimensions-ansi

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