Direct Drive Wheel Electronics Case for 110ST Servo (MKS ODrive Mini)

ElectronixBox V3 – electronics case for a DIY direct drive wheel

This 3D-printed case slips over the back of a 110ST servo and holds all the electronics of a DIY direct drive wheel base in one compact unit, directly on the motor. There are no separate boxes and no long motor or encoder cables.

What goes inside

• MKS ODrive mini (servo controller)

• XY-AP100L amplifier driving a bass shaker

• LM2596 5 V buck converter

• 50 W 2 Ω brake resistor

• 60 × 60 × 15 mm 5 V fan in exhaust

Servo fit – check before printing!
The sleeve is made for a 110ST servo that measures 111.5 mm square, with 74.5 mm flat faces on the corners, with 0.5 mm clearance per side. Servos from different brands vary, so measure yours first. The sleeve has an open passage on the +Y side so it can slide over the servo connectors. A screwed strap closes it after assembly.

Features

• Clamps onto the servo with 2× M4 screws; no extra bracket needed.

• The motor and encoder cables enter through U-slots in the right side and are held by a sliding guillotine lock.

• The rear panel has a GX12 USB (to the ODrive), USB-A (5 V out), a 3-pin Mic connector (24 V in) and a GX12 audio connector (bass shaker).

• The boot and reset buttons can be pressed through the top cover with printed stems.

• The AP100 snaps into the floor without screws, and its volume shaft comes out underneath.

• Airflow was checked with CFD (OpenFOAM). At 30 °C ambient and about 11.5 W dissipated, the exhaust air is about 32 °C and the hottest board surface about 49 °C.

Printed parts (15 types / 17 parts)
All STEP files are already oriented for printing. Just import and slice. No supports are needed.

• 01 Front sleeve

• 02 Floor

• 03 Rear panel

• 04a Rack deck + 04b Rack bulkhead (glued together)

• 05 Top cover

• 06 Left side / 07 Right side

• 08 Button stem ×2 / 09 Retaining ring ×2

• 10 MKS reinforcement

• 11 AP100 USB plug

• 12 Cable lock (guillotine)

• 13 Sleeve strap

Print settings

• PETG or ASA (not PLA, because the brake resistor gets hot)

• 0.2 mm layers, 3–4 perimeters, 20–25 % infill

• Button stems: 0.12 mm layers, 100 % infill

Hardware

• 26× self-tapping screws 2.6 × 9 mm (head Ø4 × 1.3)

• 8× M3 × 20, 2× M3 × 12, 4× M3 nuts

• 2× M4 × 10–12 + nuts

• Cyanoacrylate glue, 1–2 mm EVA/foam tape, 2.5 mm cable ties

• USB-C male plug with PCB (XN005) for the ODrive USB

Assembly
A full illustrated assembly manual (PDF) is included, with a numbered exploded view, wiring diagram, hardware list and 9 step-by-step stages.

Design
Modelled parametrically in FreeCAD.