I am here to introduce you to Andy. It is a robotic arm, and its name is a reference to the words "hand" and "handy" - that well fit with a robotic arm.
The idea was born during my holiday: a robotic arm that can rotate, stretch and shrink, able to do quite everything you want it to do, inspired by industrial machines.
Andy has a rotating base, two joins that can be rotated independently (think at them as human's shoulder and elbow), and a claw that can be rotated, opened and closed more or less strongly as you need.
The system is completely based on Arduino. Stepper and servo motors will be used.
The introduction is finished: let's design!
Step 1: The base
First of all: the base.
It has to be solid enough to hold up the whole arm, but also able to rotate.
Furthermore, it's in the base that the electronic system (Arduino) will take place.
Let's analyze the design.
On the base (1) is placed a disk (2), that rotates thanks to a motor (3). It is wired with the Arduino board, placed in the apposite box (4). This rotation is transmitted with four pins (5) to a second disk (6), that is where the rest of the arm will lie. Finally, an enclosure (7) complete the base.
Here is the procedure to recreate the design: don't worry about measuring units (mm, cm, ...), you can resize the whole thing when you have finished.
1) The base: create a box of size 20x22x1 units. Create a cylinder of radius 9.5 units, align it on one side of the box, and subtract from the box creating a circular hole 0.5 units deep.
2) The bottom disk: use the same radius (9.5) to create the disk, height 0.5. Using a 0.3x0.3 units based box create a hole at the center of the disk. The motor gear will fit in there and make the disk moving.
3) The motor: create a 3x3x3 box. Attach at the center of one face another box that measures 0.3x0.3x0.9. It is the moving part of the motor, and it will be connected to the disk.
4) The electronics: we need a box containing Arduino and other electrical components: just create a box that measure about 4x11x4 units.
5) The transmission: the bottom disk rotation is transmitted to the top disk through four pins. Just create four identical cylinders of radius 0.5 and height 9 and place them symmetrically to the center of the disk.
6) The top disk: create a cylinder with radius 6 and height 0.6. Place it on top of the four pins.
7) The enclosure: create a 20x22x10 units box. Select the four top edges, and use the tool Fillet with radius 4.
Create a rectangle that overlap the box bottom face, using the Sketch > Rectangle tool. Using Sketch > Offset create a smaller rectangle, taking away 1 unit from each side. Now, use Modify > Extrude with the setting Subtract and drag the rectangle up for 5 units. Then click anywhere on the workspace: your enclosure is now empty inside.
Using the top disk as reference, make a hole on the box using the Combine > Subtract tool.
8) The name: as every respectable project do, my arm needs a name. Open the menu on the right and select Primitives > Smart Primitive > Text. When the primitive is load, change its text to "Andy". Then resize it and place it on the frontal face of the enclosure.
Please note: The motor is fixed in its position using a block connected to the electronic box or to one side of the external box. It is not included in the picture. Moreover, the electronic box needs at least one hole, in order to take out the wires that will connect the motors with Arduino.
Andy's base is ready!
In the next step, I will create the first joint and sub-arm.