YAD Robotic Hand

  Before we start, I want to say that this project is a remix of this one: https://www.instructables.com/3D-Printed-Bionic-Hand-Skeleton/

 In the beginning, I was willing to make the hand model by myself. But, while searching for inspiration, I came across this masterpiece by HendoJ, which I found perfect for my project. 

Tools:

- Hot glue gun x1 https://www.aliexpress.us/item/3256805609563263.html

- Super glue x1

- Hacksaw or dremel (with its safety equipment) x1 https://www.aliexpress.us/item/3256806413683737.html

- Precision tweezers https://www.aliexpress.us/item/3256805403035236.html

- Sanding paper (to smooth out 3d printed parts)

- Screwdrivers

- Scissors x1

- Ruler or vernier calipers x1

- Servo Tester x1 https://www.aliexpress.us/item/3256805624294747.html

- Marker or insulation tape x1

Components:

- AC/DC adapter output 5v/8A x1 https://www.aliexpress.us/item/3256804632954670.html

- Male-to-male wire x30 https://www.aliexpress.us/item/3256803066509723.html

- Male-to-female wire x10 https://www.aliexpress.us/item/3256803066509723.html

- Arduino nano x1 https://www.aliexpress.us/item/3256806808262903.html

- 2x16 I2C LCD screen module https://www.aliexpress.us/item/3256805913767190.html

- 10k potentiometers x2 https://www.aliexpress.us/item/3256802580578325.html

- sg90 servo motors x6 (mg90s are also valid) https://www.aliexpress.us/item/3256806674688313.html

- Elastic cord +Ø2mm (1 meter) https://www.aliexpress.us/item/2255801083383369.html

- Ribbon (1 meter) https://www.aliexpress.us/item/2251832203869822.html

- Ø5mm Terminal blocks x5 https://www.aliexpress.us/item/3256805706720976.html

- Breadboard x1 https://www.aliexpress.us/item/3256806674545644.html

- Ø3mm Aluminium tube (250mm) x1 https://www.aliexpress.us/item/3256804988048256.html

- 2.1*5.5mm DC socket x1 https://www.aliexpress.us/item/3256805641341365.html

- M3x20mm screws with nuts x4

- M3x10mm screws x4

- M2.5x10mm screws x4

- M2.5x8mm screws x4

-Piece of wood 95x95x30mm

3D-printed parts:

 For 3D-printed parts I used a Makerpi P2, here are the settings and material involved:

- eSUN PLA+ warm white

- 0.4mm nozzle

- Supports

- Raft

- Nozzle temp: 190°C   bed temp: 65°C

- Infill Pattern: Grid

- Infill Density: 40%

Make sure that the fingers get printed Laying on one of their sides like this (look at the picture), except for the tips (3T and all files ending with 4) and the base of the thumb “T1”: (look at the picture)

For the remaining parts, they should be standing upright: (look at the picture)

 You have to process the 3D-printed parts before moving on. To do so, use the tweezers to remove any supports, or rafts (be gentle and careful!). You must also remove any plastic within the holes. Next, smooth out the parts using sanding paper.

P.S: You have to print five models of the pulley.

Here's The 3D stuff: https://www.thingiverse.com/thing:6680086

Objective:

• Assemble all the fingers

You will need:

- Hot glue gun

- Hacksaw or Dremel

- Aluminum tubes

- 3D-printed fingers parts (T1,R2,M4,…)

- Marker or insulation tape

- Ruler or vernier caliper

-Fingers parts

 You will first need to cut the aluminum tubes. To do so, measure the desired distance then mark it, cut, and repeat:

•  +- 15mm, QTY =12
•  +- 18mm, QTY =2

 Next, Assemble each finger part and fix it using the pins you have cut (look at the video), then hot glue each side of the hole where the pins have been inserted. The two long pins go in the thumb.

Identifying finger parts:

- Flat bottom goes first (T1, I1, M1, R1, P1)

- Round goes last (T3, I4, M4, R4, P4)

- Shortest goes before the last (I3, M3, R3, P3)

- Longest goes after the first (T2, I2, M2, R2, P2)

Finally, cut about 35cm (14 inches) of ribbon and elastic cord. Pass the elastic cord through the back loops of the finger, and the ribbon through the front loops of the finger (tweezers might be of great use):

Then pass the elastic cord through the fingertip’s hole and tie it so that it does not go back. After, double-tie the ribbon around the elastic cord.

 Well done! You got yourself functional fingies!

Objective:

• ·Assemble the base

You will need:

- 3D-printed Base parts (Base file, Fixation, Support, connection cylinder)

- Hot glue gun

- Super glue

- Piece of wood

- M3x10mm screws

- M2x10mm screws

- Ø5mm Terminal blocks

- One sg90 servo motor

- Servo tester

 First of all, fix the support to the piece of wood by screwing the four M3x10mm screws into each of the 4 screws’ holes and the terminal blocks using the M2 screws in the back of the hand.

 Next, take the connection cylinder and ensure it fits perfectly on top of the support part, if it does then glue it using super glue.

 Then, glue the other side of the C.C. to Part C (be careful it should look forward), and fix, using the hot glue gun, Part A.

 Finally, set the servo motor to the right position (with the servo tester but you can use your hands as well), and put it in its place behind the C part. After, mount the thumb on the servo and screw it down (use the screw coming along with the servo motor). At this point, you can just hot glue the B part to A and the edge of C (Do not touch the thumb with glue). Screw down the fingers using the M3x20mm screws along the nuts and the terminal blocks to the back of the hand before you pass each elastic cord through it and pull until you get the desired tension, then tighten the screws so that they block the cord inside.

   Congrats! You got a hand!

Objective:

• Modify the servo motors

You will need:

- Sg90 servo motors

- Servo tester

- DC socket

- AC/DC adapter

 In this step, you will have to modify five of your servo motors so that they continuously rotate:

1.  Disassemble the servo.
2.  Plug into the tester and set it to neutral.
3.  Using tweezers carefully turn the potentiometer until the DC motor stops.
4.  Glue the potentiometer’s edges using the hot glue gun (DO NOT put it directly from the gun, wait 2-3s for it to cool down a bit).
5.  Cut a small section off the end of the driven gear’s plastic pin.
6.  Reassemble the servo.
7.  Make sure that whenever the servo tester is on neutral the motor stops. In case it does not, redo the steps.

Here is a video that might help you: https://youtu.be/JhHSXCLsN4k?si=3OLCgErO08jIp4qi

 Next, you will have to record the servo motor’s neutral value:

For the diagram (look picture)

Servo’s signal --> D10

Potentiometer --> A0

CODE

 After uploading the code, open the serial monitor and slowly turn the potentiometer until the servo motor fully stops. Jot down the value shown and repeat for all the modified servos.

Comment: Each servo might have its unique value, so remember which goes to whom.

That is how it went out for me: (look at the picture)

Objective:

·        Attach the servos to the hand

You will need:

- Hand

- Sg90 modified

- Servo tester

- Pulleys

- Servo motor screws

- M2.5x8mm screws x4

   Set the servo motors to neutral then screw them all down to their emplacement (use the servo motor screws as well as the M2.5x8mm ones), and mount the pulleys to each servo. Next, pass each ribbon through its respective pulley and roll it around. Finally, screw down the pulleys to the servos with the spare screws:

Objective:

·        Blow life inside your hand

You will need:

- Arduino nano

- Breadboard

- AC/DC adapter output 5v/8A

- All kinds of wires

- LCD screen

- potentiometers

Servos:

Thumb --> D3

Index --> D5

Middle --> D9

Ring --> D6

Pinky --> D10

Joint --> D11

LCD:

SCL à A5

SDA à A4

Potentiometers:

Selector --> A0

Servo control --> A1

Do not forget to connect the Arduino Nano’s GND to the breadboard’s ground.

REMARK: if the potentiometers’ values jitter too much, consider connecting their GND and VCC directly to the nano’s

 Next, you will have to go through the code to replace the values T, P, R, I, and M with your own: (look at the picture)

It's pretty easy to do so. The potentiometer plugged into A1 (pot2 in the code) controls which finger you'll be flexing while the other controls the degree of the movement. To help you operate, the LCD screen displays two values:

• ·        first line: finger controlled and the range you're in (e.g.: if your value is between 0 and 100 you're controlling the joint servo, 100 and 200 thumb...).
• ·        second line: speed/direction of the servos. If you come near the stop value of the servo motor, it'll show a "hlt" which is short for "halt" (look at the picture). At this point, the direction of the servo will change depending on how you're turning the potentiometer, and the further you turn it the faster the servo will pull.

As our journey ends here, I want to profoundly thank you for reading this Instructable. It was a significant challenge for me, a teenager in my final years of school in Morocco, to accomplish this while also keeping up with my studies. For those facing similar struggles, I advise you to plan your day carefully and try waking up as early as possible. I got accustomed to sleeping early and waking up literally at 5 AM (sometimes 4 or even 3 AM), which gave me an extra 2.5 to 3 hours each day. Trust me, you won't regret it. Feel free to improve, customize, or ask any questions regarding this project—I’ll be happy to answer them one by one! 😊

Best regards

Anas Hanoun.