SDM Finger Fabrication Guide

Important Considerations:
Difficulty:	Intermediate
Min. Age:	Age 10
Time:	2.5 Hours
Est. Cost per 20 Students:	$23
Component Category:	Actuator
Control Category:	Manual
Essential Learning:	Mold Making & Casting
Safety Equipment:	Lab Gloves, Eye Shields
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Overview:

The SDM Finger Fabrication Guide is a intermediate level instructional guide to aid in the construction of soft robotic components using easily accessible materials. The guide includes detailed instructions to make a simple actuator that can be controlled with an internal cord to move the finger and pick up objects. 

Supporting Documents:

This page provides the SDM Finger Fabrication Guide, a template for mold-making and a bill of materials for all equipment and supplies that will be needed to make the actuator. These documents can be download using the "DOWNLOAD'" button to the left. 

Materials:

• Silicone elastomer
• Kevlar cord
• Cardboard
• Hot glue
• Hot glue gun
• Tubing

Prerequisites:

• Students should begin this activity with a basic knowledge of soft robotics and understanding of relevant vocabulary (i.e. actuators, sensors, controls).
• Students should have a basic familiarity with soft robotic applications within the field of prosthetics and medical devices. 

Essential Learning Objectives:

Following the activity, students should have experience making a mold, and dividing the mold into subsections to create the sections that give the finger the ability to move. Creating a two part cast is also explored, as students pour and cure two different materials into the same mold to achieve a specific movement. After analyzing the finished finger, students may take this knowledge further by expressing ways to alter the molds based on a desired result. 

Construct Mold	Create Two Part Cast	Evaluate Final Result

 

Overview of Steps:

The following is an overview of the steps associated with the guide. For more details regarding each step and for a copy of the documents this overview references please download the fabrication guide using the "DOWNLOAD" button above. 

	The SDM finger template pieces are glued to cardboard, laminated and cut out. These will become the walls of the finger mold.
	Using hot glue gun and following the lettered numbers for each piece of the template the mold pieces are assembled. The interior barriers for creating the finger sections are hole punched in the appropriate spaces marked and are folded, assembled and secured with hot glue.
	Tubing is laid between the finger's subsections to provide a channel which will later guide the cord that controls the finger. The tubing must be laid carefully to avoid leakage and also requires the top tubing piece to bend around to allow the cord to create a loop.
	Once the tubing has been secured, the first layer of elastomer is poured into the mold. This layer reaches to the tops of the finger's sections using the Dragon Skin elastomer listed in the guide. This layer must be cured completely in a curing oven or left to cure on its own before continuing.
	The second layer of elastomer uses Smooth-Sil to create the backing of the finger. This layer of elastomer should fill to the top of the mold and again be cured for listed time frame or in an oven if accessible.
	When the curing of the elastomer layers is complete the finger can be de-molded and the cord can be laced through the tubing that has been embedded into the fingers sections.
	Lastly, the cord can be pulled to control the finger's movements.

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