Assembly Guide

This guide describes how to assemble PrintExo from 3D-printed components, off-the-shelf mechanical parts, and electronics.

1. Overview

PrintExo uses a modular architecture organized into three main subsystems:

Subsystem	Description
Actuation module	Motor, planetary gear stage, protective casing
Shank structure	Vertical frame, passive hinge, calf attachment
Shoe interface	Dorsal component, plantar guides, lace integration

Assembly follows a bottom-up approach: gearbox → actuation module → shank → shoe interface.

2. Before You Begin

Checklist

[ ] All 3D-printed parts completed and post-processed
[ ] All BOM components available (bearings, fasteners, motor)
[ ] Required tools prepared
[ ] Clean, well-lit workspace

Recommended Preparation

Verify printed parts — check for warping, incomplete features, or layer defects
Ream all holes — use appropriate drill bits to clean up M3 holes
Tap threads — tap M3 holes where bolts will be inserted
Dry-fit bearings — ensure press-fit is snug but not cracked

3. Required Tools

Tool	Size/Spec	Purpose
Hex key set	2.5 mm (for M3)	Tightening bolts
Screwdriver	Phillips / Flat	General fastening
Drill bits	2.5 mm, 3.0 mm	Hole reaming
Hand tap	M3 × 0.5	Threading holes
Needle-nose pliers	—	Support removal, small parts
Calipers	—	Dimensional verification
Power drill (optional)	—	Speeds up drilling/tapping

4. Assembly Steps

Step 1 — Sun Gear Assembly

Fit the Sun Gear to the Sun Gear Holder.

Step 1

Step 2 — Align Screw Holes

Align the screw holes.

Step 2

Step 3 — Fasten Sun Gear

Fasten using six (6) M3 × 22 mm screws until each screw contacts the bottom surface.

Step 3

Step 4 — Mount Sun Gear to Actuation Module

Align the Sun Gear with the six (6) screw holes on the Actuation Module (CubeMars AK60-6 V1.1 KV140). Fasten in the specified order, then tighten fully.

⚠️ Caution: Do not let any screw tilt the Sun Gear contact surface.

Step 4-1 Step 4-2 Step 4-3

Step 5 — Planet Gear Bearing Installation

Insert one (1) HK0810 (8×12×10) into each of the four (4) Planet Gears.

Step 5-1 Step 5-2

Step 6 — Ring Gear Installation

Align the Ring Gear with the Actuation Module, then insert it fully.

Step 6-1 Step 6-2 Step 6-3

Step 7 — Secure Ring Gear

Fasten using six (6) M3 × 5 mm screws in the specified order, then tighten fully.

Step 7-1 Step 7-2

Step 8 — Carrier Bearing Installation

Insert one (1) HK0810 (8×12×10) into the Carrier.

Step 8-1 Step 8-2

Step 9 — Medial Gearbox Bracket

Align the Medial Gearbox Bracket with the bearing, then insert it fully.

Step 9-1 Step 9-2

Step 10 — Planet Gears Installation

Align the four (4) Planet Gears with the bearings, then insert them fully.

Step 10

Step 11 — Sun Gear Engagement

Align the Actuation Module Sun Gear with the bearing, then insert it fully.

⚠️ Caution: Align the teeth of the four (4) Planet Gears with the teeth of the Sun Gear.

Step 11-1 Step 11-2

Step 12 — Carrier Fastening

Insert M3 flat washers, then fasten the Carrier to the Actuation Module using two (2) M3 × 22 mm screws. Tighten fully.

Step 12-1 Step 12-2 Step 12-3

Step 13 — Medial Cover

Fasten the Medial Cover using three (3) M3 × 22 mm screws. Tighten fully.

Step 13-1 Step 13-2 Step 13-3

Step 14 — Lower Bracket

Fasten the Lower Bracket using three (3) M3 × 22 mm screws. Tighten fully.

Step 14-1 Step 14-2 Step 14-3

Step 15 — Check Assembly

Check that there are no gaps between modules.

Step 15

Step 16 — Passive Hinge Bearings

Insert two (2) HK0810 (8×12×10) into the holes in the Passive Hinge section of the Shank Structure.

Step 16-1 Step 16-2 Step 16-3

Step 17 — Shank Structure & Hinge Pin

Fit the Shank Structure to the Ring Gear. Insert the Hinge Pin, then fasten using one (1) M3 × 40 mm screw. Tighten fully.

Step 17-1 Step 17-2

Step 18 — Upper Bracket to Hinge Pin

Fasten the Upper Bracket to the Hinge Pin using one (1) M3 × 40 mm screw. Tighten fully.

Step 18-1 Step 18-2 Step 18-3

Step 19 — Upper Bracket to Ring Gear

Fasten the Upper Bracket to the Ring Gear using three (3) M3 × 22 mm screws. Tighten fully.

Step 19

Step 20 — Calf Compression Sleeve & Strap Anchor

Fasten the Calf Compression Sleeve and Strap Anchor to the Shank Structure using four (4) M3 × 22 mm screws. Tighten fully.

⚠️ Caution: Select the size option based on the user's shank length, then fasten through the corresponding holes.

Step 20-1 Step 20-2 Step 20-3 Step 20-4

Step 21 — Wire Guide

Fasten the Wire Guide using four (4) M3 × 22 mm screws. Tighten fully.

Step 21-1 Step 21-2

Step 22 — Dorsal Interface

Fasten the shoe-mounted Dorsal Interface to the Carrier using four (4) M3 × 20 mm screws. Tighten fully.

ℹ️ Note:
This step attaches the dorsal interface to the device.
Instructions for mounting the dorsal interface onto the shoe are provided in the
Shoelace Fixation Guide.

Step 22-1 Step 22-2 Step 22-3 Step 22-4

Step 23 — Auxiliary Lace

Use the Auxiliary Lace to secure the Dorsal Interface and Carrier assembly to the shoe.

ℹ️ Note:
Detailed lace routing and tying instructions are provided in the
Shoelace Fixation Guide.

Step 23-1 Step 23-2

Step 24 — Complete 🎉

Assembly complete.

Complete

5. Alignment & Fit Verification

After assembly, perform the following checks:

Mechanical Checks

Check	Expected Result
Gearbox rotation	Smooth, no grinding or binding
Hinge movement	Free inversion/eversion motion
Motor operation	Spins without obstruction
Shoe interface rigidity	No wobble at mounting point

Fit Checks

[ ] Shank aligned with lateral side of lower leg
[ ] Ankle joint axis approximately aligned with device axis
[ ] Calf sleeve secure while comfortable
[ ] Laces tensioned evenly across dorsal interface
[ ] No pinch points during range of motion test

6. Safety Notes

Do not over-tighten M3 bolts — PLA can crack under excessive torque
Inspect all structural joints before human testing
Check for pinch points around hinge and gearbox