Feed rack for a face spiral, module 1, 6 teeth, 19.05 × 8 × 7, curved teeth — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/face-spiral-feed-rack-m1-6t-w8/  (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 19.05, width 7.0, height 8.0
- 6-tooth rack of module 1 (pitch 3.14 mm), 19.05 mm long, 8 wide, teeth 2.25 mm deep (tip at +1, root at -1.25 from the pitch line), body 6 mm below the pitch line. Generated by the spiral rib: in each of seven planes across the width the rib's section was swept past the rack and the envelope taken, so the teeth are straight-flanked (20°) but curved along the rack's width, following the spiral's curvature (the tooth at the edges of the face sits about 0.3 mm farther along than at the middle). The rack ends in the middle of a space at both ends.
- Slides radially over the disc's face, its teeth pointing at the face; one turn of the disc moves it one pitch.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
module  1
teeth  6
length  19.05 mm
width  8 mm
tooth depth  2.25 mm
body  6 mm below the pitch line

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. 99: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_099.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/face-spiral-rack-feed-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/face-spiral-feed-rack-m1-6t-w8/index.json
API: https://xemstudio.com/api/geometry?object=face-spiral-feed-rack-m1-6t-w8