The Mechanical Hand (Lupe and Mary)
Author(s)
Lupe Anaya- Bell Gardens High School
Mary Eckel- Los Angeles River School
NGSS Engineering Standards
ETS1.A: Defining and Delimiting Engineering Problems
ETS1.B: Developing Possible Solutions
ETS1C: Optimizing the Design Solution
HS-ETS1-2. Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.
Materials needed
Anaya's Materials
Eckel's Materials
Plastic straws
Dental floss
Water hose washers
Small cardboard box
Sewing needle
Star shaped scrapbooking puncher
Tape
Permanent marker
Scissors
Paper straws
Dental floss
Water heater washers
Small cardboard tube
Styrofoam
Sewing needle
Plastic straws
Hole puncher
Procedure
Anaya's Procedure
1. Gather materials
Eckel's Procedure
1. Gather materials
2. Draw a straight line down the length of the straw. Make three marks (2 cm apart) on this line on four straws.
2. Draw a straight line down the length of the straw. On four of the straws, measure one inch from the top of the straw; make a mark. Then measure one inch down from the mark; make another mark. Repeat one more time.
3. Use a star-shaped scrapbooking puncher to make the cut at each mark. One point of the star should be enough.
Bend the straw to test its flexibility.
3. Cut lengthwise across the straw at each mark, being careful not to cut all the way through. Make a diagonal cut starting about 1/4 centimeter above the lengthwise cut. Repeat about 1/4 centimeter below the lengthwise cut.
4. For the thumb, make the first mark on the straw 2 cm from the top of the straw, then measure the next mark 3 cm from the first mark. Use the puncher to make the cuts.
5. Lay the fingers according to the length of your design and cut the bottom of the straws leaving enough straw length for the hand. Measure a piece of dental floss about 4 times the length of the straw and thread through the needle. Push the needle just above the first hole, guide it down the straw, and make a knot at the top.
4. On the fifth straw (the thumb), measure about 1.5 inches for the top of the straw, make a mark. Then measure 1.5 inches down from the mark; make another mark. Make cuts in the same manner as in step 3.
5. Measure out a piece of dental floss about 4 times the length of the straw. Thread through the needle. Push the needle just above the first diagonal cut and guide down through to the end of the straw.Repeat for each finger.
6. Carefully punch four holes on the top of the box with the scissors and one on the side for the thumb. Push the fingers and thumb through each hole.
7. Thread the floss of one finger through the needle and have the needle go through the bottom of the box. Remove the needle and attach a washer to the end of the floss. Repeat for all strings.
6. Using an extra straw, push four holes through a piece of styrofoam. Push one of the finger straws into each hole.
7. Punch hole four holes in the plastic straw to use as a support. Put inside the cardboard tube and push straws through the holes.
8. Test each finger and use tape to support each straw.
9. Add a glove or handle.
8. Tie a washer to the end of each string.
9. Test the fingers by pulling on the washers.
10. Test it out, pick up stuff.
10. Pick up stuff.
Questions
How do human fingers bend?
How are the fingers connected in a human hand?
How do the materials you used for the prosthesis relate to the bones, skin, tendons, joints, and muscles of your hand?
Biomedical engineers design and research new prostheses to improve their strength, durability, longevity, and life-like form. What modifications would you make to your current prototype to meet these objectives?
Photos
Lance Cpl. Bandon Mendez's myoelectric prosthetic arm
