One of the cool things about 3D printing is that we can mimic the anatomy and physiology of the human body to an amazing degree. One of the hardest concepts for younger students to grasp is how the body works and all the little parts in which play a role in even the simplest tasks.
I was inspired to do this project by a lab that I did in college with a dissected frog and pulling on the tendons to see how they played a role in movement. However, I wanted to incorporate 3D modeling to be used in an engineering class. This project ‘s main goal is designed to show how the tendons running in the forearm contribute to the movement of the fingers incorporating CAD skills combining engineering and biology.
Step 1: Purchase Materials
Basic materials other than the 3D filament can be purchased from a local drug store. If you are unable to 3D print your own pieces, you are able to order prints online by uploading your file and having pieces shipped to you. The materials used are based upon the template provided, but any improvements or modifications as seen in “Step 3” may require additional materials. We have included the model for the connection pins, but wire is an effective replacement.
1 spool of 1/16” wire
5 rubber bands
1 spool of 1/8” nylon rope
Step 2: Download Fusion 360
Fusion 360 is available for download for free and runs on both Mac and PC.
Step 3: CADing Your Model
Students will be responsible to CAD their own models or modify the existing model. Basic template of the CAD model is available through this website. Assembly will depend on modifications to existing model therefore “Step 4” is based on basic template that a student has created.
Step 4: Assembly
Unless modified, general construction follows the steps listed below.
1) Lay out the pieces as seen on the CAD diagram, and insert wire pieces through the pegs and holes in the finger joints
2) Identify the front (palm) and back of the “hand”
3) Tie the nylon string to the palm side of the fingertips and string it through the fingers down to the arm
4) Cut a rubber band in half and tie it so the loops are about 2.75” or 7 cm apart (tip to tip)
5) Place rubber bands on the pegs on the back of the hand to mimic the resisting force to return fingers back to default position
6) Have students pull on strings to mimic finger movement