CNC'd Plywood Children's Push Bike

Overview

Role - Mechanical Designer | Manufacturing

Tools - AutoCAD, Fusion 360, 3D printing, 3-axis CNC Router

Skills - CAD Design, Rapid prototyping, Mechanical design, Manufacturing, Hardware integration, Testing & validation, Toolpath creation

Design Process

The objective of this project was to design and manufacture a children's balance bike using CNC-routed plywood and custom 3D-printed components while working within strict material and budget constraints. The design prioritized manufacturability, efficient material utilization, structural integrity, and rider ergonomics.

The project began by sourcing wheels and axles from a used children's bicycle, allowing the frame geometry to be designed around readily available components. Modern balance bike geometry was researched and incorporated to create a frame that accommodated a range of rider heights while maintaining stable handling characteristics.

The frame was designed in AutoCAD using a minimal number of structural members to reduce material consumption while maintaining rigidity. Particular attention was given to plywood grain direction, load paths, and clamping locations to maximize strength and ensure the bicycle could safely withstand expected loading conditions.

Design for Manufacturing (DFM) and Design for Assembly (DFA) principles guided the development of the frame and components. Fusion 360 was used to generate CNC toolpaths and optimize part nesting, allowing every component to be manufactured from a single sheet of 1/2 in. plywood measuring less than 2 ft × 4 ft while minimizing waste. Custom 3D-printed components were incorporated where they simplified assembly or provided functionality that could not be achieved using plywood alone.

Following manufacturing, the bicycle was assembled and evaluated for structural performance, ergonomics, and overall functionality. Testing identified several opportunities for future improvements, including lock-on handlebar grips, a more comfortable seat, and an increased steering range to further enhance the user experience.

Results

The completed balance bike successfully met the project's design objectives, producing a lightweight and structurally rigid prototype capable of safely supporting loads exceeding 150 lb. The adjustable seat accommodated a wide range of rider heights, allowing children of different ages to comfortably and safely operate the bicycle.

The manufacturing process demonstrated efficient material utilization by producing the complete frame from a single sheet of 1/2 in. plywood measuring less than 2 ft × 4 ft. Combined with custom 3D-printed components, the project validated an effective digital manufacturing workflow that balanced structural performance, manufacturability, and ease of assembly.