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Updated Split Hook


split_hook.gif The split hook has been around since 1912 (at least), and is the most popular terminal device. Versions are made by Hosmer, [WWW]RSLSteeper, [WWW]Otto Bock, and others.

We'd like to update this time-tested design to include some features that would improve this classic, including making it out of polymers to lighten it, including rubberized inserts to aid in holding objects in place with the sides, and other improvements.

Other efforts have been made to make the hook cheaper to make, most notably [WWW]this effort, at Arizona State, although no product is known to be available. OPP has unsuccessfully contacted the authors in an attempt to secure the donation of this design to the public domain.

The most popular design is the Hosmer-Dorrance 5x (shown at left).
This funky Otto Bock design (right) shares some characteristics. body_powered_4.jpg

The shadow box pictures at the bottom of this page were created by Open Prosthetics volunteer Chris Wescott, who has also taken a stab at modeling the hook.

Some extra info from Chris on the orientation of the pictures: "Each one was taken at a specific angle of rotation. For instance the first part one of the hook (one without the extra arm) was taken at 0, 90, 111.625 & 201.625 degrees. The other part of the hook (with extra arm) was taken at 0, 90, 105.75, and 205.75 degrees. You will notice that I took one picture with the bolt hole normal and then one perpendicular to the shot for both parts. The other two shots were taken where the flat side of the hook was parallel with the shot and then one 90 degrees from that point."

Problem Statement

Produce a lower-cost all-polymer version of the standard split hook. Duplicate the functionality of the standard split hook, and add additional functionality as allowed by the material. Interface with existing wrist units OR a custom all-polymer rotating wrist unit.

Add ability to trigger touch screens, such as capacitive screens that dominate the smart phone market.

Design Requirements

We would like the device to:


part1_1.jpg part2_1.jpg

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