15. Mechanical and Machine Design

3D Textured Art CNC Machine

Machine Brief

This CNC machine was designed to redefine artistic expression by automating part of the artistic processes. Artists gain unparalleled control over material manipulation, fostering creativity and precision in their work. With a focus on innovation and accessibility, this project seeks to empower artists of all backgrounds to explore new realms of creativity.

Group Documentation Page

My Role and Contribution

My primary responsibilities included the full redesign of the machine, the extruder design and manufacturing, and contributing to the printing and assembly of the entire machine, in addition to setting up the Marlin software. This involved cutting components to size and connecting and assembling them. These tasks were mainly my contributions, and they were pivotal in bringing the project to fruition.

Design Phase

Using Fusion 360, i edited and redesigned each component to ensure optimal functionality. Our design journey began with an existing design by Nikodem Bartnik, which can be found on Instructables. We selected this design as our foundation due to its robustness and versatility. However, to meet our specific requirements, we made significant modifications:

1. Component Modifications:

   • Changed several components to improve durability and performance.
   • Adjusted the dimensions of the machine, making it larger in the X and Y axes to accommodate bigger workpieces.

2. Z Carriage Redesign:

   • Redesigned the Z carriage to accommodate a silicone extruder instead of the original Dremel tool. This involved creating a custom mount and ensuring proper alignment and stability.

3. Exporting for 3D Printing:

   • After finalizing the design, each component was exported in STL format.
   • These STL files were then imported into Cura slicer for slicing and subsequent 3D printing.

Iterative design iterations allowed us to refine our concepts, striking a balance between form and function. Considerations such as material properties, assembly methods, and compatibility with off-the-shelf components were paramount in the design process. Our modifications ensured that the CNC machine would be suitable for creating 3D textured art with a silicone caulking extruder.

Design Fusion 360 Files

Ordering Components

We embarked on a thorough selection process, evaluating components based on criteria such as compatibility, quality, and cost-effectiveness. Extensive research and communication with suppliers ensured that each component met our needed requirements. By prioritizing reliability and performance, we aimed to lay a solid foundation for the CNC machine’s construction.

3D Printing

First, each part was exported as an STL file, and then imported to Cura slicer to slice the part. Utilizing the Ultimaker S5 3D printers, we translated our digital designs into tangible parts. Careful consideration was given to printing parameters such as layer height, infill density, and print orientation to achieve optimal strength and surface finish. Post-processing techniques including support removal, sanding, and smoothing further refined each printed component to meet our exact standards.

Assembly

With meticulous attention to detail, we started with the assembly process. Each component was carefully integrated and assembled, with a focus on alignment and fitment. Through methodical assembly techniques and quality control measures, we aimed to create a CNC machine that would deliver consistent performance and reliability.

Frame Assembly

The assembly of the frame represented a critical phase in the construction process, requiring careful consideration of structural integrity and stability. The 2020 aluminum extrusions were cut, tapped, and assembled. Attention to detail and adherence to design specifications were vital to ensure the frame’s ability to withstand the operation. The lead screws and chrome rods were measured and cut to size using an angle grinder.

Extruder Design and Assembly

The design and assembly of the extruder were approached with a focus on precision and reliability. Considering various design options for the extruder, iterating through multiple prototypes to ensure smooth material deposition and consistent performance. Below are the four ideas explored:

Design Idea	Description	Pros	Cons
Rack and Pinion	Used a rack and pinion mechanism to push silicone out from the tube.	Simple design, easy to implement	Limited control over extrusion speed
Lead Screw with Rotating Nut	Used a lead screw with a rotating nut actuated by a belt and stepper motor.	Precise control, consistent extrusion	Complex assembly, higher friction
Lead Screw with Conversion Block	Converted rotating motion into translational motion using a lead screw and block	Improved precision and control	More components, increased complexity
Lead Screw with Lead Screw Nut (Chosen Design)	Attached a lead screw nut to an outer sleeve (PVC tube) to create a linear actuator.	High precision, smooth operation, reliable	Requires precise alignment and assembly

Chosen Design

The fourth design was selected: a lead screw with a lead screw nut attached to an outer sleeve, creating a version of a linear actuator driven by a stepper motor. This design was chosen for its high precision, smooth operation, and reliability.

Modeling in Fusion 360

The chosen design was carefully modeled in Fusion 360. The process involved: - Designing the lead screw and lead screw nut to fit precisely within a PVC tube. - Creating a custom mount to securely attach the stepper motor. - Designing and printing a coupling piece to join the lead screw nut to the PVC pipe. - Ensuring the entire assembly allowed for smooth translational motion with minimal friction.

Enhancements and Adjustments

• Lubrication: After initial testing, lubrication was added to the lead screw to facilitate smoother movement.
• Friction Enhancement: Sandpaper was applied to the end of the sleeve (tube) to increase friction between it and the silicone tube, preventing the tube from rotating with the lead screw.

Iterative prototyping and testing allowed us to refine the design, ensuring smooth material deposition and consistent performance.

Extruder Fusion 360 Files

Electronics Setup

The electronics setup involved the careful integration of various components, including stepper motors, drivers, and control boards. A thorough understanding of electronics principles and best practices guided the setup process, with a focus on safety and efficiency.

Components and Their Purposes

Component	Purpose
12V Power Supply	Provides the necessary power for all the electronic components, ensuring consistent and reliable operation.
Arduino Mega	Acts as the main controller for the CNC machine, running the firmware and sending commands to the stepper drivers.
CNC Shield for Arduino	Connects to the Arduino Mega, facilitating the connection of stepper drivers and providing a streamlined setup for controlling the motors.
A4988 Stepper Drivers	Control the stepper motors by regulating the current and managing the step signals, allowing precise control of motor movement.
Stepper Motors	Drive the movement of the CNC machine’s axes, translating electrical pulses into mechanical motion.

Setup Process

1. Power Supply:

   • Installed a 12V power supply to power the Arduino Mega and the stepper drivers.

2. Arduino Mega and CNC Shield:

   • Mounted the CNC shield onto the Arduino Mega. The CNC shield provided a convenient way to connect the stepper drivers and motors to the Arduino.

3. Stepper Drivers:

   • Installed A4988 stepper drivers onto the CNC shield. Adjusted the current limit on each driver to match the stepper motors’ requirements.

4. Stepper Motors:

   • Connected the stepper motors to the CNC shield through the stepper drivers. Ensured that the wiring matched the correct pin configuration for proper operation.

Wiring Diagram

To ensure a smooth and error-free setup, we followed a detailed wiring diagram. The connections were made as follows: - Power Supply to Arduino Mega and CNC Shield: Connected the 12V power supply to the power input terminals on the CNC shield. - Stepper Drivers to CNC Shield: Plugged the A4988 drivers into the designated slots on the CNC shield. - Stepper Motors to Drivers: Connected the stepper motors to the output terminals on the A4988 drivers.

Final Adjustments

• Carefully checked all connections to ensure they were secure and correctly aligned.
• Adjusted the potentiometers on the stepper drivers to set the correct current limit for the motors.
• Tested each motor individually to verify proper operation and make any necessary adjustments.

Software Configuration

Introduction to Marlin Firmware

Marlin is an open-source firmware for the RepRap family of 3D printers. It is highly customizable and widely used for its reliability and versatility. For our CNC machine, Marlin was chosen due to its robust features and extensive community support.

Editing Marlin Firmware using Arduino IDE

To configure Marlin for our CNC machine, we used the Arduino IDE. The following steps outline the key modifications made:

1. Axis Configuration:

   • Configured the X, Y, and Z axes to match the dimensions and movement parameters of our CNC machine.
   • Calculated and set the steps per millimeter for each axis to ensure precise movement.

2. Temperature Sensor Override:

   • Since our CNC machine does not use a traditional hot end, we had to bypass the temperature checks in Marlin.
   • This was done by setting one of the temperature sensors to a fixed value, allowing the firmware to operate without needing to reach a target temperature.

Installation and Uploading

1. Installation:

   • Installed the Arduino IDE and the necessary libraries to work with Marlin firmware.
   • Downloaded the latest version of Marlin from the official repository.

2. Uploading to Arduino Mega:

   • Connected the Arduino Mega 2560 to the computer via USB.
   • Selected the appropriate board and port in the Arduino IDE.
   • Compiled and uploaded the customized Marlin firmware to the Arduino Mega.

Steps per Millimeter Calculation

The steps per millimeter for each axis were calculated based on the lead screw pitch and the stepper motor specifications. The formula used was:

Steps per mm = (Motor Steps per Revolution × Microstepping) / Lead Screw Pitch

Config Files

To access the Marlin configuration files used for this project, follow this link.

Summary

By configuring Marlin firmware, we ensured that our CNC machine operates smoothly and efficiently. The customization process allowed us to tailor the software to meet the specific needs of our machine, overcoming challenges such as the temperature sensor override to achieve successful extrusion.

Initial Testing

Preparation

With the software configured and uploaded, we embarked on the initial testing phase. This involved:

1. Powering Up:

   • Connected the power supply to the CNC machine.
   • Ensured that all connections were secure and free of short circuits.

2. Connecting to the Computer:

   • Used a USB cable to connect the Arduino Mega to the computer.
   • Opened a control software such as Pronterface to send commands to the CNC machine.

3. Homing the Axes:

   • Sent G28 command to home the X, Y, and Z axes.
   • Observed the movement to ensure that each axis moved correctly and returned to the home position.

Calibration

1. Steps per Millimeter Adjustment:

   • Measured the actual movement of each axis and compared it to the expected movement.
   • Adjusted the steps per millimeter settings in the firmware to correct any discrepancies.

2. Movement Testing:

   • Sent manual movement commands to move each axis a specific distance.
   • Verified that the movement was smooth and accurate.

3. Extruder Calibration:

   • Calibrated the extruder by measuring the amount of material extruded over a set distance.
   • Adjusted the extruder steps per millimeter in the firmware to ensure consistent material flow.

Test Patterns

1. Simple Shapes:

   • Started with simple shapes such as squares and circles to test the machine’s accuracy.
   • Observed the quality of the cuts and the precision of the movements.

2. Complex Patterns:

   • Progressed to more complex patterns and designs.
   • Evaluated the machine’s ability to handle intricate details and maintain consistent quality.

Adjustments

Based on the initial tests, several adjustments were made to improve performance:

1. Speed and Acceleration:

   • Tweaked the speed and acceleration settings to find the optimal balance between speed and accuracy.
   • Reduced the speed for more intricate patterns to ensure better detail.

2. Extruder Settings:

   • Fine-tuned the extruder settings to achieve consistent material flow and prevent clogging.

Documentation

Throughout the initial testing phase, detailed notes and observations were recorded. This documentation helped in troubleshooting issues and making informed adjustments. By following a systematic approach to testing and calibration, we ensured that the CNC machine would deliver reliable and high-quality results.

Conclusion

The successful construction of our CNC machine marks a significant achievement in our quest to redefine artistic expression through automation. By carefully designing, assembling, and calibrating each component, we have created a machine that not only meets our initial objectives but also offers a platform for future innovation and exploration in 3D textured art. The knowledge gained and the challenges overcome during this project have equipped us with valuable skills and insights that will undoubtedly contribute to our continued growth and success in the field of digital fabrication.