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Print-in-place: captive wheel on a printed axle (Ø40 × 12)

Name: Print-in-place: captive wheel on a printed axle (Ø40 × 12) dimension sheet
Creator: Xem Studio
License: https://creativecommons.org/licenses/by/4.0/

How do you 3D print a wheel already on its axle? · Hardware · basis: Xem Studio design: revolved profiles, axle and wheel coaxial, one designed running gap of 0.40 mm

Also called: print in place wheel, print in place axle, captive wheel 3d print, wheel on axle stl, print in place caster wheel

Exact dimensions. True size, with no printing tolerance added.

length: 40.0 mm
width: 40.0 mm
height: 20.0 mm

Notes

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.

Print-in-place: captive wheel on a printed axle size chart

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)

Where the files are

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

Xem Studio

Print-in-place mechanism design (geometry computed in the generator)

web

Xem Studio design

Free files

★ Free files 3 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json

print-in-place-captive-wheel-axle-assembly	The whole print as laid on the bed (2 bodies, already assembled); STEP keeps each moving body a separate solid	STEP · STL
print-in-place-captive-wheel-axle-wheel	Wheel Ø40 × 12 with a 45° V tyre groove and six Ø7 windows; bore Ø8.8 with 45° counterbores top and bottom	STEP · STL
print-in-place-captive-wheel-axle-axle	Printed axle: Ø8 journal, 45° base cone Ø12 on the bed, 45° head Ø13, stem to z 20, Ø3.4 through hole	STEP · STL

Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.

Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=print-in-place-captive-wheel-axle

Print-in-place: captive wheel on a printed axle (Ø40 × 12), isometric render of a generated part — Render of print-in-place-captive-wheel-axle-assembly from the free STEP; not to scale.

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Questions

How is the wheel held on the axle?

By two 45° cones on the axle — a base cone Ø12 below the wheel's Ø8.8 bore and a head Ø13 above it — each 0.40 mm (square to the cone) from a matching counterbore in the wheel.

How much end play does it have?

0.57 mm each way: the 0.40 mm gap measured square to a 45° face is 0.40 / sin 45° along the axle.