COMPUTER-CONTROLLED-MACHINE
TOOLS
CNC
| Parameter | Description |
|---|---|
| Machine Type | 3-axis CNC router used for cutting and machining flat materials. |
| Model | SD-1325 CNC router. |
| Working Area | Approximate working area of 1300 × 2500 mm |
| Z Axis Travel | Around 200 mm vertical movement for tool positioning. |
| Axes | Three axes of movement: X, Y, and Z. |
| Spindle Speed | Adjustable spindle speed up to about 24,000 RPM. |
| Spindle Power | Usually between 3 kW and 5.5 kW depending on the machine configuration. |
| Motion System | Rack and pinion system for X and Y movement and ball screw for the Z axis. |
| Frame Structure | Steel frame designed to provide stability during machining. |
| Worktable | Aluminum T-slot table used to fix the material in place. |
| Control System | CNC controller compatible with Mach3, DSP or similar systems. |
| Supported Materials | Wood, MDF, plywood, acrylic, PVC, foam, and other soft materials. |
| Tool Holder | ER collet system used to mount cutting tools. |
Safety training
A safety and machine operation training session was conducted where the basic machining parameters and some design considerations necessary for the workflow were explained.
One of the concepts discussed was pass depth, which refers to the amount of material removed in each tool pass. It was recommended that the cutting depth should be equal to or smaller than the diameter of the cutting tool in order to avoid overloading the end mill and reduce the risk of tool breakage. The concept of feeds and speeds was also explained, which defines the rotational speed of the tool and the feed rate during the cutting process.
Because end mills are circular, internal corners cannot be perfectly square. This problem can be solved by adding dogbones, which allow the parts to fit properly during assembly.
Examples of press-fit structures were also presented. In this type of design, the parts are manufactured from flat sheets of wood or MDF and later assembled through slots without using screws or glue. This design approach allows complex objects, such as furniture, to be fabricated using only CNC cutting processes.
Setup and Toolpath
The design used for the development of the model is as follows.
Before starting the CNC router operation, the necessary personal protective equipment (PPE) was used to ensure safety in the work area: safety glasses, hearing protection (earmuffs), and a filtered respirator. These were used to prevent exposure to dust particles, noise generated by the spindle, and possible material projections during the machining process.
The structure design was imported into the Aspire software in DWG format, where the cutting operations and toolpaths were defined. These toolpaths are later interpreted as G-code instructions.
The geometry of all the parts was arranged within the workspace according to the dimensions of the material (18 mm MDF).
In this case, a 6 mm flat end mill was selected from the tool library. This selection was important because the design required several press-fit joints between different parts, as well as defining parameters such as cutting depth, feed rate, and spindle speed.
The toolpaths were exported using the Mach2/3 Arcs (mm) post-processor, which converts the machining operations into G-code compatible with the Mach3 control software.
The material clamping system on the CNC worktable uses metal clamps to prevent any displacement during the machining process. However, to avoid possible interference between the cutting tool and the clamping system during the toolpath movement, an additional material is placed underneath the workpiece to act as a support.
This material functions as a sacrificial layer, serving as a protective surface between the material being machined and the machine worktable. This improves the stability of the material and helps prevent damage to the table surface when performing full-depth cuts. Although this is a conventional method commonly used in this type of equipment, we implemented it to improve precision and safety during the machining process.
The cutting tool used was a 6 mm flat end mill, installed in the machine spindle to perform the cutting and profiling operations on the MDF material.
Once the material was placed on the worktable, it was secured using the clamping system to ensure stability before starting the machining process. At this stage, the correct position of the board, the firmness of the clamping system, and the available workspace for executing the generated toolpaths were verified. In this case, the dimensions of the material were suitable for the machine's working area (1.22 m × 1.22 m).
The machining process was controlled using the Mach3 software, which functions as the control interface for the CNC machine. This program interprets the G-code previously generated in the CAM software and translates it into movements of the machine axes (X, Y, and Z).
In this interface, the toolpath file generated during the design stage is loaded, allowing the operator to control and monitor the machining process.
Before starting the machining process, it is necessary to verify the reference coordinates, the tool position, and the available workspace to ensure that the cutting operations follow the intended design. Once these checks are completed, the machining process can be started using the Cycle Start command.
In this piece, we obtained the expected result according to the original design. However, during the machining process we noticed that the material was slightly affected by residues from previous materials used on the same CNC machine.
The support material (sacrificial layer) presented irregularities caused by earlier machining operations, which slightly affected the stability of the material and caused a minor unexpected movement during the cutting process. Despite this, the geometry of the piece was successfully machined and the toolpaths were executed as intended.
Assembly
After the machining process, the pieces were assembled using press-fit joints.
