Waveshare ESP32-P4 3.5" OV5647 Camera Focus Knob

A removable focus-adjustment knob for the OV5647 camera on the Waveshare ESP32-P4 3.5" dev board, whose enclosure recesses the lens behind a small hole.

This lens has no autofocus — focus is set by rotating a tiny notched barrel by hand. Fingernails are imprecise, and tweezers slip and gouge. This gives a positive, non-slip grip and a broad finger wheel to dial focus in small, repeatable fractions of a turn — ideal for pulling the factory ~1 ft focus in closer for frame-filling QR scanning. A central sight hole lets you watch the live camera feed through the knob while you adjust.

How it works:

• A hub drops into the enclosure hole and reaches down to the recessed lens; the enclosure hole holds it steady, and the wheel sits flush on the enclosure surface.
• Four internal teeth drop into the four notches on the rotating barrel and turn it.
• A broad wheel above the enclosure gives easy dexterity for fine adjustment.
• Counter-clockwise (from the front) = focus closer; clockwise = farther. Lifts straight off — non-permanent.

Using the 4.3" ESP32-P4 board instead? That housing is different — see my separate "ESP32-P4 4.3in OV5647 Camera Focus Knob" listing. https://www.thingiverse.com/thing:7377999

Fit: barrel ~5.42 mm OD, 4 notches @ 90°, sized for the 3.5" board's recessed enclosure hole. Fully parametric (build123d); the STEP file is included to retarget it.

Printing: print flange-up (broad flat face on the plate) — big first layer, the hub prints upward, no supports. 0.2 mm nozzle recommended, PLA/PLA+. Recipe: Bambu P1S, 0.2 mm nozzle, 0.10 mm layers, 0.14 mm first layer, 65 C bed.

Credit: engagement pattern confirmed against ArkoXS's Raspberry Pi Camera v1.3 focus tool (https://www.printables.com/model/530968-raspberry-pi-camera-v13-focus-tool), same OV5647 notched-barrel family, then rebuilt parametrically. Thanks to ArkoXS.