Hi friends in this video we will see how to make a simple and awesome sphere drawing robot. Actually, this project experience wasn't that awesome, of course I encountered problems and I came up with my own solutions to make the project a good one. In this video you will find not only how to make the project, but also possible problems and solutions.

In the first step of the project, I will assemble the 3D parts and build the robot, if you don't have a 3D printer you can use PCBWay's 3D printing service. 

In the electronics part of the project, the source code is based on Atmega328P, and ULN2003 motor drivers are required for the stepper motors.

You can build the project on a breadboard following the circuit diagram, but as you know I prefer to design a printed circuit board for a more professional prototype. I prefer PCBWay for printed circuit boards in my projects. You can choose PCBWay for low-price and high-quality printed circuit boards.

Let's continue the project by soldering the components used on the printed circuit board, you can find the components and BOM list above.

After soldering, complete the connection of the motors, 5-volt power supply, and USB connections, then let's move on to programming.

Download the EggDuino source code by going to the GitHub page whose link I shared in the video description, unzip the zipped file and edit the folder name, then copy the EggDuino folder and paste it into the Arduino Libraries folder in the My Documents folder.

Open the EggDuino source code, if the Accel Stepper library is not installed, you should install it first. In the bottom lines of the source code, you can see the pin order to which the Stepper Motors are connected, you can update the motor pin here. There is also the pin number to which the Servo motor is connected in the upper lines. If you have done all the updates, select the Arduino board and the port it is connected to and upload the source code.

Inkscape software version 0.91 will be used to create templates and draw, find and download the installation file for your operating system. Then complete the installation of the software.

At this stage, we need to install EggBot version 2.7.1, a popular extension to enable Inkscape software to communicate with the board and get a control interface. Download the right package for your operating system, extract the zipped folder, copy all the files in the Extensions folder. Then go to the file location where Inkscape is installed, find the Extensions folder in the Share folder and paste the files into it.

Now we are at the most important update part, if you have done some research for EggBot, you can see many entries about the extension causing communication problems with different boards like Arduino. You can solve this problem with three different methods, open the ebb_serial.py file with a text editor, find the lines shown on the screen. 

The first solution is to enter the USB port address to which the Arduino board is connected and define it directly. However, if you want to use a different USB port after this change, you need to update the port address again.

The second solution is to add a serial port definition named "Arduino" along with the serial port definition named "EiBotBoard".

The third and last method is to enter the value of your board's device path instance directly, which is also available in the device manager. I chose to use all three methods together, be sure to save the file after making the changes.

The programming part to control the sphere robot is done, now open Inkscape software, then select Egg-Bot from the templates, and import a sample vector image and insert it into the template. Open EggBot control from Extensions, this interface allows you to easily adjust many settings.

First enter the Servo up and down angle values and click Apply, you will observe your pen moving up and down.

Then you can also manually send some commands to the robot and observe the movements at the same time. For now, everything seems to be ready, the communication with the robot is working without any errors.

As you can see, many prints have failed, and from all these experiences I have identified three problems.

The first is that the hobby stepper motor has some slack in the shaft and as a result the pen axis wobbles.

At first I was going to replace the motor, but I realized that this problem is chronic in the same type of motors, so I had to either use a larger more stable motor and throw the whole project in the trash, or find another solution.

So I attached a simple rubber band to the motor on the axis where the pen is located, and then stretched the rubber band and fixed it to the main part with the help of a thumbtack.

Thus, when the pen axis is running, the shaft slack jerk of the motor is prevented by the rubber band. 

The second problem was that the brackets holding the sphere were too hard and did not grip the sphere properly.

I designed new sphere holders and added suction cups on the ends so that the sphere can move in a balanced way.

Finally, I reduced the timing values in the Egg-Bot control interface in order to balance the shaft slack of the stepping motor on the sphere axis and to make a smoother drawing.

As a result of all these solutions, I obtained more balanced and smoother drawings. This project aims to build a simple and budget-friendly sphere drawing robot, this project can be improved with higher quality motor types. Thanks for reading, I hope this project has contributed to you.