This instructable takes you through the process of building your own cool robot arm!

The Robotic Arm is developed entirely by me, the nut covers are however, from a guy on thingiverse. All STL files are avilable for you to print (for personal use - not for selling!) on our GitHub.

So let's get to it!

Step 1: Parts Needed

First you will need some parts. Besides the 3D printed parts, which I will introduce in the next section, you will need bearings, nuts and bolts. I have spent some time on reducing the number of unique items on the BOM, but there is still a few.

Bolts:

1 pc. M8 x 40 mm
1 pc. M8 x 70 mm
4 pcs. M4 x 20 mm
4 pcs. M4 x 35 mm
20 pcs. M3 x 10 mm
3 pcs. M3 x 16 mm
10 pcs. M3 x 20 mm
9 pcs. M3 x 25 mm

Nuts:

21 pcs. M3
8 pcs. M3 self locking
8 pcs. M4 self locking
2 pcs. M8 self locking

Washers:

2 pcs. M8, OD: ~15.8 mm
2 pcs. M4, OD: ~8.8 mm

Bearings:

4 pcs. 608Z
12 pcs. 624Z

Rods:

Aluminium rods, the diameter is outer diameter, they are of 1 mm material, making the inner diameter of the 15 mm rods = 13 mm. I found these rod sizes (diameters) in the local hardware store.

1 pc. 15 x 200 mm
1 pc. 15 x 150 mm
2 pc. 6 x 170 mm
1 pc. 6 x 165 mm

Additional items:

Super glue
Micro servo
3 pcs. NEMA 17 stepper motor
3 pcs. uStepper control boards (optional)

Tools:

Adjustable wrench
Hex Keys (if you use hex bolts like I did)
Philips screwdriver

Step 2: Printed Parts

Now for the 3D printed parts. First of all, I printed all of them in PLA. The infill was set to 25% for all parts, besides the three motor gears which are printed with 100% infill. The numbers on the parts will be used in the assembly instructions given in the following section. All STL files are available on our GitHub for personal use.

Step 3: Assembly

Just follow the instructions in the pictures here. The only thing to notice is that the motor gears has changed since I took these pictures. This was done to make them more robust, and get a better grip on the motor.

Step 4: Electronics

For the robot arm to run, you will need some stepper driver. I recommend uStepper, but there are plenty of other solutions out there. What I go through here is based on the uStepper setup.

The three uSteppers are connected as shown here on the diagram. One uStepper is master, receiving data through the UART and distributing this to the two slaves.

To make it easy, I used a prototype shield on the master so that I could easily connect bluetooth module, servo and slaves.

If using USB cable for communication, it is essential that it is secured properly to avoid breaking the USB on the uStepper when rotating the arm.

Step 5: Programming

Programming the arm is relatively easy, since I have already made a working sketch :) The sketch is based on a teach mode operation principle. That is, you move the robot arm around and record positions, which you then play back. The code setup is shown in the video below, and the code is found on our GitHub.