Encountering faulty or damaged knobs on devices is an all-too-common experience. To address this issue, I have engineered a fully parametric Fusion 360 design that allows you to 3D print knobs tailored to a wide array of D-shaped shaft sizes.
Initially, I considered providing pre-generated model files for various shaft dimensions. However, upon gathering data from potentiometer and rotary encoder manufacturers, it became evident that the dimensions are rather arbitrary with no discernible standard. Additionally, you may wish to customize tolerances to better suit your specific needs, which would result in an impractical number of models.
Dimensions
The above drawing shows the dimensions for the example print and serves to illustrate various components of the knob.
Fusion 360 Design Parameters
The Fusion 360 design offers granular control over key dimensions, potentially eliminating the need for post-processing.
Important Parameters
shaft_diameter,shaft_length,shaft_d_thickness: Enter the exact dimensions of your shaft here. These should be precise measurements, as the model automatically incorporates the necessary spacing and tolerances.tolerance_index: This parameter defines the fit of the knob on the shaft. Adjust to make the fit tighter or looser. Each increment or decrement of “1” changes the spacing by 0.01mm. A value of “55” is a solid starting point for well-calibrated printers.knob_diameter,knob_height,knob_angle: Control the knob’s outer dimensions using these parameters.spring_thickness,spring_knob_height: The “spring thickness” affects how thick the wall of the spring is when printed. The default value of 0.86mm works well with a 0.4mm nozzle. Adjust only if your nozzle size causes issues. The “spring knob height” dictates the spring’s force against the shaft’s flat side, which can degrade over time when using materials like PLA.dial_line_width,dial_line_depth,dial_line_offset,dial_line_angle: These settings control the dial line’s appearance and orientation. The angle can be adjusted between -180º and +180º.
I have successfully utilized this knob design in replacing various knobs on different devices, and I hope you find it equally beneficial.
