Final Project¶

My final project captures most of the topics that I learned during the past weeks in Fablab Bahrain and some of the engineering experience that I received during my studies as a mechanical engineering student in Bahrain Polytechnic.

Explanation:¶

The high price of artificial organs of all kinds negatively affects their users, the idea inspired by this project is to create a prosthetic hand through 3D printing and some cheap material but effective.

Difficulties¶

My lack of experience in joints specialization may slow down the project, which will need a lot of experiments and a lot of experimental models.
Challenge the time to complete the project within a simple period of time (two weeks)
The design phase needs a lot of time because all the members will be designed from the beginning (the finger contains three parts, the thumb contains a fourth part, the palm of the hand, thread holes, joints holes that will contain screws…etc.)
Low experience with Arduino and coding that take a long time to set the components and wiring them with soldering them in Veroboard.

Design Phase¶

(SOLIDWORK software is used for the most parts)

*NOTE: all files converted from SOLIDWORK to Fusion360 to have web view in the website.

I started with the fingers parts as it is the most complicated part;

Each part contains holes 3.2mm as the used screw is 3mm, and each part have a section as half a circle in front & back to hold the rubber band elastic fabric (Elastic band)& Monofilament fishing line.

Elastic band:¶

Elastic is a narrow, stretchy fabric that is made from rubber or spandex cores that are wrapped in polyester, nylon or cotton fiber. The fiber-covered cores are braided, knit or woven together to form the elastic fabric. I used it outside the hand to release the finger to the original position.

Monofilament fishing line:¶

is the most basic and most common fishing line out there. Made out of nylon extruded in a single, continuous filament and left untwisted, monofilament fishing line is a good all-around line that is smooth and a bit stretchy. I used it inside the hand to easily move the fingers and close & open the finger.

2D and 3D Modeling¶

Finger section¶

(3D print)

Here is the modeling and design of one finger and it will be applied on all the fingers all same in the project.

Palm section¶

(3D print)

Here is palm part that will connect the fingers with the wrist

all the three fingers will be connected by 3mm screw (thumb, index and middle)

Thumb connector section¶

The finger needs a connector with the palm section to have better movement, so I designed this part to be the link between them

wrist section¶

(Laser Cutter + Acrylic Bending)

Here is the wrist design

3D printing process¶

Fingers sections and palm section used the 3d printing and followed the same process that attached in week4 (3d scan & print).

Laser cutter¶

I converted the circle dimensions to rectangle to have the right dimension to cut the Acrylic sheet by the laser cutter.

This is the website that helps me to convert the circle to rectangle:

I used Inkscape software to draw the 2D sketch for the wrist.

Inkscape wrist file for laser Cutter (as dxf file)

Acrylic Bending¶

The oven used to heat the Acrylic sheet to have a flexible sheet to bend it easily. on 200 °C arond 5 to 6 min, while checking the texture of the sheet.

Then by heat resistance gloves, the bending mold was a pipe.

After heating start Bending

Red marks show the used gloves and the pipe

Here is the bending Acrylicsheet on the pipe

then we pull the pipe to see the final shape and remove the cover stickers

I decided with Mr.Abduallah that the shape wasn’t perfect and unnormal, so we reheat the previous shape to re-bend it with other mold which is a previous prosthetic hand made from inmoov company by Mr.Abdalgafoor.

This is the new used mold from inmoov company:

we observed that the acrylic sheet back to the original shape After being exposed to heat:

Final Result of the wrist section;¶

Materials¶

Qty	Description	Price	Link
1	PLA Filament	18.99 $	https://tinyurl.com/ca8kwpbt
1	screw of Suleve	21.03 $	https://tinyurl.com/f98w5zab
1	Acrylic Sheet 6mm	4.12 $	https://tinyurl.com/k2jba5c3
1	wires	6.00 $	https://www.instagram.com/elec360.bh/
1	microcontroller	15.9 $	https://www.instagram.com/elec360.bh/
1	servo motor	37.00 $	https://www.instagram.com/elec360.bh/
1	other electronic components	13.00 $	https://www.instagram.com/elec360.bh/

Joints, screws & assemble¶

All the parts are assembled by the screw 3mm with different length, the lock parts are by the nut

The joints between the fingers part was attached with the fishing line & elastic band (shows as red arrow).

Circuit projects¶

Used components in first phase; Arduino nano board, servo motor, 1k ohm resistors (4), LEDs (2), push buttons (2), breadboard and hook-up wires.

I started to do it;

I connected to my laptop and start upload the code which is provided below.

Code¶

Use the three backticks to separate code.

#include <Servo.h>
Servo s;
int servo_position = 0;
int servo_pin = 10;

int led_pin_1 = 6;
int led_pin_2 = 5;
int button_1 = 8;
int button_2 = 7;

void setup() {
  pinMode(led_pin_1, OUTPUT);
  pinMode(led_pin_2, OUTPUT);
  pinMode(button_1, INPUT);
  pinMode(button_2, INPUT);
  s.attach(servo_pin);
}

void loop()
{
  while (servo_position < 180 && digitalRead(button_1) == HIGH) {
    servo_position++;
    s.write(servo_position);
    digitalWrite(led_pin_1, HIGH);
    digitalWrite(led_pin_2, LOW);
    delay(10);
    }

  while (servo_position > 0 && digitalRead(button_2) == HIGH) {
    servo_position--;
    s.write(servo_position);
    digitalWrite(led_pin_2, HIGH);
    digitalWrite(led_pin_1, LOW);
    delay(10);
    }
}

Finalize¶

I don’t have enogh experice in soldering, so i asked the Mr.Abdalgafoor to help me to solder the circuit in the vero board to have more fixed circuit. so the the video shows the process that we go throw it .