How to make a DIY robotic arm grabber. A simple and cheap robotic arm controlled by a DIY controller. This is a great science fair project for aspiring engineers, makers, and people who are into robotics.
- 1/8 inch plywood
- plastic gear set
- 4 gearbox motors
- 8 – 3 position switches
- 1 controller pcb (note: PCBway is having a free prototyping event from Oct 25th to Dec 10th )
To build the robotic arm i first obtain some 1/8 inch peices of plywood . To construct the arm we will first need to cut these pieces into smaller pieces of the correct measurements. Below are the pieces that need to cut along with their dimensions
Next we will take the square piece and attach the motor to it. To do this you will need to drill a hole into the center of the piece of wood. The hole should be the size of the motor’s axel and glue should be added to the axle so it stays in the hole. Another square piece of wood will need to be cut and a larger hole will need to be drilled in the middle of it. The large hole in the square piece of wood should be large enough so that the motor fits through it. This piece should then slide over the motor and be attached to the body of the motor
Now that the base is complete, the robotic arm can now be built. A medium length rectangular piece should e glued upright and the motor can be mounted in it by drilling a hole in the rectangular peice. after attaching a gear to the motor, another hole the size of a dowel should be drilled near the top of the rectangular piece. the dowel can then be mounted into the hole and 2 longer rectangular pieces can be mounted on the dowel along with a large gear.
Notice the motor has a small gear mounted to it and the arm has a large gear attached to it. This small to large gear ratio will make the arm rotate slower and will increase the torque the motor can apply. Also note the back of the arm has some overhang. this will be where a counter weight is attached .
The grabber must now be built. to build the grabber i cut out 3 pieces of wood. 1 piece of wood to serve as a mounting platform and 2 pincers. The mounting platform should have a large hole drilled in it to mount the motor and 1 other small hole to add a dowel to. 1 pincer and gear should be mounted on the dowel, another pincer and gear should be mounted on the motor.
Once the grabber is complete it needs to be mounted to the rest of the arm. A dowel is placed through the grabber and arm to be used as a hinge. A motor with a gear attached is then mounted to the arm and another gear is mounted to the dowel.
Next the electrical work needs to be added. Wires will need to be soldered to every motor and should be long enough that they can hook up to the remote control
For the controller I will use a PCB that i designed and had printed at PCBway. The Pcb will provide a simple, compact and reliable way to build a controller for our robotic arm. THe files for the PCB can be found here
To make the controller first solder the 3-postion switches into the 8 spots available for the switches. Once that is complete solder the wires for the motors into the 8 holes available for the + and – of each motor. Finally solder the wires for the battery into the 2 holes near the battery symbol. To control the robotic arm simply push both switches upwards to make the respective joint move in a direction and push the switches downwards to make that joint move in the opposite direction. Keep the switches in the middle position if you want the arm moving in neither direction.
After adding a wooden case to the controller the arm can then be tested.