12. Mechanical Design, Machine Design¶
Disassembly and Cleaning Process of the Machine¶
First, we disassembled the machine to perform a thorough cleaning. This was necessary because the equipment had not been used for a long time and had not received proper maintenance. During this period, dust, dirt, and material residues had accumulated on the parts and inside the mechanisms, which could affect its operation. Disassembly allowed us to access internal components that are difficult to clean during regular maintenance. We carefully removed the main parts, taking care not to damage them, and conducted a thorough cleaning using special cleaning agents. This helped eliminate contaminants, corrosion, and old lubricants. After cleaning, a visual inspection of the parts was carried out, which helped identify worn or damaged elements for further repair or replacement. This preparation will ensure more reliable and long-lasting machine performance.
After the machine was completely disassembled, we decided to distribute the tasks among ourselves to make the most effective use of each team member’s strengths and ensure high-quality completion of all stages of work.
- Mkhitar took on the creation of the 3D model, as he possessed the necessary knowledge and experience in 3D modeling, which was an important step for the subsequent assembly and setup of the equipment.
- Derenik handled the electronics and adjustment of all electrical components, as he had experience working with similar systems and understood their specifics.
For me, working with the machine for metal processing was a new process since I had no prior practical experience in this area. Understanding the importance of a careful and responsible approach, and wanting to avoid mistakes, I decided to carry out this part of the work under the close guidance and mentorship of Mkhitar, who has significant experience and deep knowledge in metalworking and working with such equipment. This collaboration allowed me to quickly acquire the necessary skills, improve the quality of the tasks performed, and ensure safety while working with the equipment.
Thanks to this distribution of roles and mutual support within the team, we were able to organize the workflow more efficiently and cohesively. This contributed to productive work and ensured a high level of preparation of the machine for further use and subsequent stages of the project.
Manufacturing¶
When Mkhitar completed the creation of the 3D model for the adapter to add stepper motors to the lathe, we went to Mkhitar’s brother’s factory, where there is a metal processing machine. There, he explained to me the basic principles of working with the machine and introduced me to the safety rules.
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The main safety rules when working with the machine include:
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Always use personal protective equipment: safety glasses, gloves, and ear protection.
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Before starting work, check the equipment for proper functioning and ensure there are no foreign objects in the processing area.
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Never touch moving parts of the machine while it is operating.
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Keep the workplace clean and organized to avoid injuries and accidents.
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In case of any malfunctions, immediately stop the machine and inform the mentor or responsible person.
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Work carefully with tools and materials, avoiding sudden movements.
G-code Generation¶
After that, we proceeded to generate the G-code for modifying the factory part. This step was crucial for precise and correct machine control during the processing. To eliminate backlash and ensure smooth movement of all axes, Mkhitar made additional modifications to the design, bearings were installed on each axis, significantly improving the accuracy and stability of the mechanism. Additionally, he slightly repositioned the axes closer to each other, which enhanced the rigidity of the structure and reduced potential vibrations during operation. All these improvements contributed to higher quality and more reliable part modification, ultimately enhancing the overall performance of the machine. Detailed information about the G-code generation process can be read here.
To generate the G-code, we used Fusion 360, selecting the Milling section under the Manufacture workspace, and then choosing the 2D submenu. Among the available toolpaths, we selected the Bore operation, as it is ideal for machining and precisely enlarging circular holes. This tool allows for a wide range of parameters to be defined, such as diameter, depth, feed rate, cutting strategy, and other machining settings that help ensure high-quality results.
Using this operation, we created the required toolpath while taking into account the specifics of the material and the level of precision needed. The parameters used for generating the G-code in our case are shown below. They were carefully selected based on the specific requirements of the task and the geometry of the part, which allowed us to achieve a stable and reliable machining result on the CNC machine.
After setting all the parameters, it is possible to run a simulation to visually review the exact toolpath. This allows for an early assessment of how the machine will process the part, ensuring that the paths are correct and helping to identify any potential errors or collisions before actual machining begins. Simulation is a crucial step that helps prevent defects and increases the overall reliability of the process.
Milling Process¶
After reviewing the simulation, it was time to secure the material to the worktable. The table is equipped with special slots where clamps can be inserted. It is very important to position and firmly fix the part so that it does not shift or vibrate during machining. We also made sure that the working part of the machine would not come into contact with the clamps during the execution of the program. This is especially important to prevent damage to both the tool and the equipment.
A very important step in generating G-code is setting the zero point. Since we needed to modify a factory part for our task, we decided to place the zero point at the center of the main moving axis. To accurately set this point on the material fixed to the table, I used a special attachment designed to locate the center of a round hole precisely.
The special mechanical attachment features a dial indicator with a pointer that responds to minute deviations when the machine spindle rotates. This dial serves as a precision positioning indicator. The attachment also includes a specialized probe with a spherical tip, which, upon contact with the inner surface of the hole, causes the pointer on the dial to move with each spindle revolution.
To accurately determine the center of the hole, it was necessary to manually adjust the X and Y axis coordinates with extreme precision, performing micro-adjustments in small increments. The goal was to minimize the pointer’s oscillations, the smaller the oscillations, the closer the hole’s center aligns with the tool’s position. Ideally, with a perfectly shaped hole, the pointer should remain stationary, indicating an exact zero point alignment.
However, in our case, the circular hole was deformed due to prolonged use and wear, leading to irregularities and distortions in its shape. This significantly complicated the adjustment process, and it was impossible to completely eliminate the pointer’s oscillations. Nevertheless, we managed to reduce the deviations to an acceptable level, allowing us to accurately set the zero point for subsequent machining.
The zero point on the Z-axis in our case was set at the surface of the material. After the zero point was found and saved, we loaded the G-code into the machine and started the milling process.
A key difference between working with metal and wood is the necessity of constant lubrication and cooling of the milling tool. For this purpose, the machine is equipped with special sprayers located near the cutter: one supplies liquid for lubrication and cooling, while the other is connected to a compressor that provides compressed air to remove chips and prevent overheating. This comprehensive approach ensures efficient metal machining, prolongs tool life, and improves the quality of the part’s surface.
The video shows the result after installing the bearings and assembling the gears in their designated positions. Thanks to the precise fitting of the bearings and proper alignment of all components, we managed to significantly reduce the backlash in the transmission. The mechanism now operates more smoothly and stably, with minimal clearance, ensuring smooth rotation and high positioning accuracy. This is especially critical for systems using stepper motors, where even slight backlash can affect motion precision.
Adapter for Stepper Motors¶
For the adapter for the stepper motors, we decided to use a 25 mm thick aluminum alloy sheet. This material was chosen due to its strength, light weight, and good machinability, making it optimal for creating a durable and precise part.
When creating the toolpath program in Fusion 360, I used several types of machining operations, each serving its purpose in the manufacturing process. The parameters for each operation were selected taking into account the material properties and the design features of the part and are listed below.
- 2D Adaptive — I used this method for rough machining to efficiently and quickly remove the bulk of the material from the sheet. This toolpath optimizes feed rate and cutting depth, reducing the load on the cutter and extending its lifespan.
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Drill — This operation was used for drilling holes of the required diameter and depth. Drilling was an important step for creating accurate mounting points for fasteners and other components.
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Bore — I applied this for reaming the pre-drilled holes to achieve high dimensional accuracy and perfect finish of the internal surfaces. This operation helped eliminate potential deviations and ensure precise sizing.
- 2D Contour — This operation was used for finishing both the external and internal contours of the part. It allowed me to create smooth, clean edges and give the part its final shape with a high-quality surface finish.
Below is a simulation of the machining process, demonstrating the sequential actions of the machine during the part’s processing. The visualization shows all stages of the work, from rough machining to finishing, illustrating the precise movement of the tool and its interaction with the material.
Since the backside of the aluminum material was uneven, we decided not to cut through it completely during the first setup. Instead, we left approximately 1 mm of material to keep the workpiece securely fixed and prevent any movement during machining. This is especially important when working with metal, as even slight shifts can result in defects or damage to the tool.After completing all the main operations, such as drilling, boring, roughing, and finishing the contours, we removed the part from the table, carefully flipped it over, and refixed it using a special clamping fixture. This ensured a stable and precise position during the second setup. Next, we performed the final operation: removing the remaining 1.5 mm layer. This not only leveled the bottom surface but also allowed us to completely separate the finished part from the base material. This approach helped maintain dimensional accuracy, prevent burrs, and simplify further post-processing.
The video shows the milling process of the adapter. It provides a detailed view of how the machine processes the material according to the pre-generated G-code. You can see the tool following various paths, performing roughing and finishing operations, drilling, and boring holes, as well as the final contouring. The footage clearly demonstrates the precision of the machine’s operation, the stability of the material fixation, and the specific characteristics of machining aluminum alloy.
Protective Box¶
To ensure safe operation of the machine, we decided to design a protective enclosure that would prevent chips and other small particles from entering the operator’s workspace, as well as reduce the risk of accidental contact with moving parts of the equipment. In addition, a special vacuum attachment was designed to efficiently collect and remove chips directly during the machining process.
I modeled all components of the protective system using the CAD program Rhino, which allowed precise adaptation of the size and shape of the parts to the machine’s workspace and structure. For the enclosure, we chose a 5 mm thick acrylic sheet, which offers sufficient strength and transparency for visual monitoring of the process.
The dimensions of the protective enclosure were calculated so that it fits snugly on the table where the machine is installed, without restricting access to control elements and maintenance areas. To securely fix the enclosure to the worktable, mounting screws were used, ensuring structural stability and minimizing vibrations during machine operation.
The attachment was designed taking into account the specifications of the Total vacuum cleaner available in our laboratory. During the design process, I considered the dimensions and connection type to ensure a tight and reliable fit for efficient chip removal.
For the prototype fabrication, I used 3D printing with PLA plastic. This method allowed me to quickly produce an accurate part with the required shape and easily make modifications and print updated versions if needed. This approach significantly saved time and ensured ease of use.
The electronics processes can be seen in Derenik’s documentation.