Worm wheel (helical, non-throated), module 1.5, 30 teeth, helix 5.36° RH, for the 1-start Ø16 worm — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/worm-wheel-helical-m1-5-30t-for-1start-d16/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown's figure (1868); true size, no printing allowance
Catalog version: 2026-10-20

Overall (mm): length 47.99, width 47.95, height 10.0
- Involute helical gear used as a worm wheel: transverse module 1.5 (= the worm's axial module), 30 teeth, helix angle 5.36° right hand (= the worm's lead angle, same hand), normal module 1.49, normal pressure angle 20°; pitch Ø45, tip Ø47.99, root Ø41.27, face 10 mm, Ø8 bore. Centre distance with its worm 30.5 mm, axes crossed at 90°.
- A non-throated worm wheel: worm and wheel are both involute helicoids, so the pair is a crossed-helical gear pair — exactly conjugate at every position, with point contact (a hobbed, throated wheel wraps round the worm and gives line contact; this plain helical form is the one used for light drives and for 3D-printed sets, and it needs no axial positioning).
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
transverse module  1.5
teeth  30
helix  5.36° RH
normal module  1.49
pitch Ø  45 mm
tip Ø  47.99 mm
face  10 mm
bore  Ø8
centre distance  30.5 mm

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Henry T. Brown (1868, public domain): Five Hundred and Seven Mechanical Movements — scan on archive.org — web — Publisher's page; dimensions are facts — https://archive.org/details/fivehundredseven00browiala
- 507movements.com: Brown's movement No. 31: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_031.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/worm-and-worm-wheel-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/worm-wheel-helical-m1-5-30t-for-1start-d16/index.json
API: https://xemstudio.com/api/geometry?object=worm-wheel-helical-m1-5-30t-for-1start-d16