Overview
AutoCurtain
Natural light is the strongest signal the body uses to set its circadian clock. Getting sunlight immediately after waking is one of the highest-leverage habits for locking in a consistent wake time. AutoCurtain automates it: an Arduino fires at 6:00 AM, the curtains rise, and at 11:00 PM they close.
Commercial motorized curtain systems start north of $200. The full BOM here is under $50: a $1 aluminum pipe, $5 lids, and a cheap 12V DC gearmotor. Universality comes from the set screw shaft coupler, which clamps onto the curtain rod axle by tightening a set screw from the outside. It accepts any rod shaft under half an inch in diameter, which covers nearly every curtain system on the market.
Design
The main body is standard 3-inch aluminum tube stock, lightly sanded to a brushed finish. Using off-the-shelf pipe eliminated a turning operation and kept the cost down without sacrificing the look.
Fitting a gearmotor coaxially inside a 3-inch bore rules out spur-gear sidepacks. A planetary stage solves this: the ring, planet, and sun gears all share the motor axis, so the entire drivetrain fits within the tube diameter. The 5:1 reduction multiplies torque enough to drive a loaded curtain from a standstill without stalling the motor.
All structural parts were machined from aluminum on a Haas CNC VF2. Tight bore fits on the gearbox housing and the 8mm shaft coupler keep runout negligible over a long run life.
| Motor | 12V DC brushed |
| Gearbox | 5:1 planetary, coaxial, fits within Ø3.00″ bore |
| Main Body | Ø3.00″ OD × 4.93″ aluminum tube, brushed finish |
| Material | Aluminium, as machined |
| Shaft Coupler | Set screw type, accepts any rod up to ½″ diameter |
| BOM Cost | Under $50 (vs. $200+ commercial) |
| Controller | Arduino (timed relay) |
| Schedule | Raise at 6:00 AM · Lower at 11:00 PM |
| Machined on | Haas CNC VF2 |
Running daily since March 2026.