Issues faced while fabrication and assembly:
Originally, we decided to use a section of aluminum square tube to make our frame, but we made an error with stock orders and ended up with a piece that was too small to use for the frame. As a result, we made a last-minute design change to make our entire frame from laser-cut 3mm acrylic instead. The frame joinery was bonded together with epoxy and reinforced with multiple gussets throughout the body, but we still ended up with far more compliance in the frame than anticipated which did affect our walking performance slightly.
Another issue we faced as a result of the frame material change was the slipping of the timing belt at the motor. Because the acrylic frame was bending under the tension we required for the drive belt, we had to adjust the motor to the maximum tension the frame could withstand, reinforce the motor side of the frame with more epoxy, and misalign the drive belt to help prevent the timing belt teeth. Had we had time to plan, we could have lengthened the frame by a small amount and used more gussets to reinforce the area around the motor mount. Alternatively, we could have fabricated the frame from 6mm laser-cut acrylic instead, but due to the schedule of TIW before fall break and the increased cut time that comes with 6mm acrylic, we did not see that solution as feasible at the time.
Future Tips:
- Always perform tolerance cuts before the whole design, saving you time and material.
- Have a lead time while ordering material, helps you with the timeline of design.
- Have a backup of parts where you think there could be a point of failure in the design.
- Finally nothing is impossible if you have the determination to do it.