Custom replacement knob for D, round and square shafts

Is a control knob missing, loose or fitted with the wrong shaft socket? Create a replacement for suitable potentiometers, rotary encoders and hobby equipment. Set the shaft shape, socket depth, outer dimensions and indicator independently. Circumferential grooves form the grip, while an optional radial pilot prepares an M3 locking screw. What you can customise: Sockets for single-flat D, smooth round or square shafts. Fit allowance added to shaft size and adjustable socket depth. Grooved grip, recessed indicator and optional screw locking. How to measure: 1. Identify the shaft shape. Measure full diameter for round and D shafts, or across opposite flats for a square shaft. 2. For a D shaft, calculate flat depth as full diameter minus the flat-to-opposite-round-edge measurement. Measure exposed shaft length. 3. Check room for the knob diameter and height. Set the indicator direction and use a trial fit to tune allowance for the printer and material. Assembly and trial fitting: 1. Deburr the socket and trial-fit without force. The knob must not rub against the housing. 2. If locking is selected, tap the 2.5 mm radial pilot M3. Fit a suitable grub screw separately; locking is required for round shafts. 3. Align and secure the knob gently. Check free rotation, indicator position and retention during intended use. 3D printing notes: Print with the closed visible face on the bed and the shaft opening upwards. PLA or PETG can be used for an indoor prototype. Starting profile: 0.16–0.2 mm layers, four walls and 40% infill; inspect the socket and indicator in the slicer. Fit and torque capacity require a physical test. Fit and included geometry: For simple manual controls after checking dimensions. No splined, knurled or double-flat shaft sockets. This is not a validated replacement for gas, cooking, heating or safety-related machine controls. Heat resistance, torque and fit have not been physically tested. Screw and tap are separate.