Instructions for Fabrication of the Shoe Spring Attachment Prototype

This section outlines the step-by-step process for fabricating and assembling the shoe spring attachment prototype, incorporating both commercial and purposely designed components.

Materials Needed

- Brass buckles (20mm x 20mm)

- Conical spring (80mm free length, 20mm small diameter, 50mm large diameter)

- EVA foam (for shoe frame, buckle strap, and sole component)

- Sewing materials (thread, needle)

- Adhesive (if necessary for securing components)

- 3D printer (for sole component if applicable)

Step-by-Step Fabrication and Assembly

Prepare the Shoe Frame

Cut the EVA foam to the appropriate size based on the patient’s shoe size. Ensure that the frame is designed to fit comfortably around the existing shoe while allowing space for the other components. Design and create any necessary slots or interfaces on the underside of the shoe frame to accommodate the conical spring and sole component.

Sew Buckles to Shoe Frame

Position the brass buckles at designated points on the outer sides of the shoe frame. Using a sewing machine or hand sewing, securely attach each buckle to the frame with strong thread to ensure durability.

Attach Straps to Shoe Frame

Cut two straps from EVA foam, each 20mm in width and long enough to comfortably secure around the patient's shoe. Sew these straps to designated points on the inner side of the shoe frame, ensuring they align with the corresponding buckles.

Install Conical Spring

Connect the small diameter end of the conical spring to the underside of the shoe frame at the heel section. Ensure that it fits snugly into any pre-made slots. Attach the large diameter end of the conical spring to the sole component, ensuring a secure fit that allows for proper shock absorption during use.

Prepare Sole Component

If using a 3D printer, generate G-code for printing the sole component with a 60mm diameter using EVA foam material. Print or cut out the sole component from EVA foam, ensuring it has a smooth surface for contact with both the ground and spring.

Final Assembly

Align and press together all components—the shoe frame, straps, buckles, conical spring, and sole component—ensuring that everything fits securely. If necessary, apply adhesive in areas where additional bonding is required to enhance stability.

Prototype Verification

Test the comfort and stability of the assembled mechanism by having participants wear it while walking. Adjustments may be needed based on feedback regarding heel elevation and overall fit.  Evaluate how well the device interfaces with different types of shoes (e.g., sneakers, sandals) to ensure versatility in use.

Compliance Testing

Conduct tests according to ISO standards relevant to medical devices (ISO 19408:2023, ISO 24263:2020, etc.) to ensure that all components meet safety and performance requirements. Document all findings and make necessary adjustments based on testing results.