The J1.2 prototypes start from the same dimensions as the previous joints. To address the issues from the previous joints, the following changes were made.

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- To fix the issues with the joints bending on different axis than the main axis, the J1.2 prototypes had a fixed point of rotation. To do this, the joints were modeled to have a hole for a metal pin to go through that fixes the pieces together. 

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- Excess force on the tendons being needed to bend the finger was resolved by moving the tendon channels farther from the center of each joint segment. The channel radii were also decreased to restrict the range of motion more. 

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In addition, to prevent the finger from bending backwards, the design of each joint was altered so that when in fully upright position, the back of each section was in contact with both other sections. 

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​Notes:

An error was made in placing the stops on the back of each joint, and they were placed too low, resulting in the ability of the finger to bend backwards beyond upright position. In addition, the point of rotation has very thin sections of resin, and is fragile. 

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Recommendations:

For future prototypes, I recommend fixing the placement of the stop on the back of each joint, as well as reinforcing the joint by thickening the thin sections, especially around the point of rotation. ​​​The channels should also be decreased in radius further, or moved farther from the center so that the moment of applied force is greater.