Sets J1.4 and J1.5 are included in this page because they are very similar and don't have many unique comments.

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The J1.3 prototypes aim to address the issues with the channels being too close to the center, as well as the tendons having too much freedom of movement. The stops on the back of each segment were also excluded in this set.

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The J1.4 set was the same as the J1.3 set, with greater tolerances on the hinge, and the stops included. However, J1.4 had an error with the proportions, and was updated to J1.5.

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J1.3 was the first set integrated with Arduino and servos. To assemble the hinges, a metal pin was placed through the center of each hinge. Using the socket designed with the first set of prototypes, strings were threaded through the channels, and affixed to the top of the J1.33. The strings were attached to a servo, which was then connected to an Arduino Uno to test the device. The prototype performed well, bending and extending smoothly, and mimicking the motion of a finger throughout extension. (Footage not currently available).

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​Notes:

​J1.3 had issues with tolerances. The point of rotation had rubbing in several spots. J1.5 aimed to stop the rubbing, and did improve it.

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In terms of the actuation of the finger, while the finger had a smooth range of motion, the joint could not resist a large amount of tension due to multiple factors. The string used had some stretch in it, and the servos were not able to prevent movement under significant force. 

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Recommendations:

 The J1 prototypes all have the similarity of material rubbing at the hinge. They also don't utilize the whole width of the joint segment for the hinge, so they are inherently limited in terms of the strength of the hinge. I recommend redesigning the hinge to improve the strength, as well as removing any locations where the joint rubs against itself and creates unnecessary friction. Also consider different options for tendons, as string is not durable, has a large amount of friction, and an unpredictable amount of stretch.

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I recommend keeping different options for servos and microcontrollers in mind, as the current setup is bulky and doesn't fit inside the size of a hand. 

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