Print-in-place: captive wheel on a printed axle (Ø40 × 12) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/print-in-place-captive-wheel-axle/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design: revolved profiles, axle and wheel coaxial, one designed running gap of 0.40 mm
Catalog version: 2026-10-20

Overall (mm): length 40.0, width 40.0, height 20.0
- 3D print in place — prints already assembled, moving, in one job. Drawn at true size with no printer tolerance added; the 0.40 mm running gaps are part of the design.
- Running gap 0.40 mm per side, 0.80 mm on diameter — part of the design, drawn as is. On the 45° faces the same 0.40 mm is measured square to the face (0.57 mm along the axis).
- Bed: the wheel lies flat, axle vertical. Both bodies start on the bed: the wheel on its full face, the axle on its 45° base cone inside the wheel's lower counterbore.
- Support while printing: the wheel's lower counterbore narrows upward at 45° over the axle's base cone; the axle's head widens upward at 45° inside the wheel's upper counterbore; nothing in either body overhangs more than 45°.
- Captured by the two cones: the axle's base cone (Ø12) cannot pass up through the Ø8.8 bore and its head (Ø13) cannot pass down through it, so the wheel cannot leave the axle.
- Freeing it: hold the axle stem and turn the wheel a full turn each way; push the axle up and down once to break the first layer apart.
- Motion: continuous rotation about the axle; free end play 0.57 mm each way and 0.40 mm radial, both from the geometry. No stops.
- Mount: an M3 screw through the axle's Ø3.4 hole, or press the stem into a Ø13 socket.

key  value  what
gap_mm  0.4  running gap per side on every moving interface (radial, axial, under captured parts) — part of the design, not a tolerance
wheel_d_mm  40.0  wheel diameter
wheel_w_mm  12.0  wheel thickness
pin_d_mm  8.0  axle journal diameter
bore_d_mm  8.8  wheel bore (journal + 2 × 0.40)
head_d_mm  13.0  axle head diameter (45° cone from the journal)
base_d_mm  12.0  axle base-cone diameter on the bed
axial_play_mm  0.57  free end play each way from the drawn position (0.40 square to the 45° cones)
radial_play_mm  0.4  free radial play
rotation_deg  360 continuous  wheel about the axle
stem_h_mm  8.0  axle stem above the wheel
screw_hole_d_mm  3.4  through hole along the axle (M3)

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Xem Studio: Print-in-place mechanism design (geometry computed in the generator) — web — Xem Studio design — https://xemstudio.com/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 3 parts): https://xemstudio.com/files/hardware/print-in-place-captive-wheel-axle/index.json
API: https://xemstudio.com/api/geometry?object=print-in-place-captive-wheel-axle