Spur gears, module 2.5: 10 to 80 teeth (20° involute) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/spur-gears-module-2-5/  (CC BY 4.0)
Basis: ISO 53 basic rack: 20° pressure angle, addendum m, dedendum 1.25 m; pitch Ø = m × teeth, tip Ø = m × (teeth + 2), root Ø = m × (teeth − 2.5)
Catalog version: 2026-10-20

Sizes: see table below
- Centre distance of two module 2.5 gears = m × (N1 + N2) / 2. Face width 20 mm, plain bore (add a hub, key or set screw to suit). Teeth below 17 are drawn without profile shift, so they undercut as real unshifted gears do.

teeth  pitch_dia_mm  tip_dia_mm  root_dia_mm  face_mm  bore_mm
10  25.0  30.0  18.75  20.0  7
12  30.0  35.0  23.75  20.0  8
14  35.0  40.0  28.75  20.0  10
15  37.5  42.5  31.25  20.0  11
16  40.0  45.0  33.75  20.0  12
18  45.0  50.0  38.75  20.0  14
20  50.0  55.0  43.75  20.0  15
22  55.0  60.0  48.75  20.0  17
24  60.0  65.0  53.75  20.0  19
25  62.5  67.5  56.25  20.0  20
28  70.0  75.0  63.75  20.0  22
30  75.0  80.0  68.75  20.0  24
32  80.0  85.0  73.75  20.0  25
35  87.5  92.5  81.25  20.0  25
36  90.0  95.0  83.75  20.0  25
40  100.0  105.0  93.75  20.0  25
42  105.0  110.0  98.75  20.0  25
45  112.5  117.5  106.25  20.0  25
48  120.0  125.0  113.75  20.0  25
50  125.0  130.0  118.75  20.0  25
56  140.0  145.0  133.75  20.0  25
60  150.0  155.0  143.75  20.0  25
64  160.0  165.0  153.75  20.0  25
70  175.0  180.0  168.75  20.0  25
72  180.0  185.0  173.75  20.0  25
80  200.0  205.0  193.75  20.0  25

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- ISO: ISO 53 standard basic rack (20° pressure angle, addendum 1 m, dedendum 1.25 m) and ISO 54 modules — standard — ISO; dimensions are facts [verify license at link] — https://www.iso.org/standard/5768.html

Free files (CC BY 4.0, Xem Studio; STEP + STL, 26 parts): https://xemstudio.com/files/hardware/spur-gears-module-2-5/index.json
API: https://xemstudio.com/api/geometry?object=spur-gears-module-2-5