Implementation Design

In implementation, we aimed to minimize any factors that could reduce the force outputted by our mechanism.

Most all of our considerations were driven by our prototype design. Below is an image of said prototype.

Issues with this prototype included:

• Excessively fast motor with low torque
• Rough motion
• Flexure of linkages

As a result, we considered the following two factors to drive our implementation:

• Torque
• Friction
• Rigidity

To address torque, we first identified that our prototype failed to maximize the power of our DC motor. Our prototype achieved reasonable speeds by underpowering the motor, as a result the motor had low torque. For our final implementation, we decided to run our motor at full speed but at a 1:3 gear ratio. This way we could adequately power for optimal torque while achieving a reasonable speed. Below is an image of our gearing system that employed the use of a timing belt.

To address friction, we recognized that our bearings were low quality and that our links were rubbing against each other. As a result, we purchased higher quality 7mm tall skate bearings to use alongside 6mm thick laser cut wood. The higher quality bearings allowed for much smoother motion. Meanwhile, employing 7mm tall bearings on 6mm thick wooden linkages ensured that there was adequate spacing between linkages for the links to rotate without rubbing against one another. Below is an image the exemplifies how our links were spaced to prevent surface friction.

To address rigidity, we recognized 2 issues with our prototype: weak link material and single link motions. On our prototype, we 3d printed all of our links; however, as depicted in the prototype image above, these links often fractured under shear stresses. Moreover, these links tended to flex with little force. As a result, we instead implemented wooden laser cut links that were double the thickness of our prototype links. These links were much more study and resisted flexure under load. We also replaced our ground links with stainless steel rods that would ensure adequate strength under load. To address the weakness of single link motion, we decided to reinforce our final implementation by doubling and or tripling each link of our mechanism. This stacking resulted in an extremely rigid mechanism. Below are images of our final implementation. These images depict the use of metal rods as well as wooden, stacked linkages.