How to Make

Open-Source Leg v1.0

The OSL is assembled from both machined and stock components. In selecting components used throughout the OSL, the design attempted to minimize the price, lead times for machined parts, and the number of vendors from which stock parts are purchased. The vendors employed along with the cost associated with each vendor are enumerated below.

Machined Parts (Star Prototype)

Actuators and Encoders (Dephy Inc)

Belts (SDPSI)

Bearings and Fasteners (McMaster-Carr)

Shafts (Misumi)

Angular Bearings (Motion Industries)

Batteries and Case (Amazon)

Magnets (K&J)

Shipping Charges

Total Cost










The detailed Bill of Materials (BOM) can be downloaded here. In the “Parts to Order” sheet of the BOM, you’ll find parts organized into different subsystems represented by column A. Solidworks part numbers are located in column B, McMaster-Carr part numbers are in column C, quantity is listed in column D, and a link is embedded in column E. Note that this BOM does not contain parts to build the E-stop, which is an emergency stop button that is highly recommended to be installed for safety reasons as OSL is a high power device.

Drawings and STEP files for all the machined parts can be downloaded and sent to Star Prototype for manufacturing. The drawings highlight only special features (hole placements, counterbores, etc.) and are not fully dimensioned. Click on any of the links to download the STEP files and drawings for a given joint. You may also view previously made quotes from Star Prototype including a quote for two knee and ankle prostheses to demonstrate how the order quantity affects the price.

Drawings/STEP Files for Knee w/ SEADrawings/STEP Files for Knee w/o SEADrawings/STEP Files for AnkleSTEP File for OSL v1.0 Assembly
Quote for Knee ProsthesisQuote for Two Knee ProsthesesQuote for Ankle ProsthesisQuote for Two Ankle Prostheses

To order parts from Star Prototype, compose a message similar to the sample e-mail, attach the drawings and STEP files, and send the message to Dara Shabnam ([email protected]) for manufacturing. Note that the current quotes specify part finish color to be either natural or black. If you would like a different color, please communicate this to the manufacturer in the email.

For those that would rather purchase a fully-built OSL, it can be purchased from Humotech.