Week 07

Assignment Requirements

Assignment Requirements

Weekly planning

During the week, we carried out various activities that presented significant challenges but were also very rewarding, especially due to the opportunity to share and learn together. We met virtually with our colleagues in the node and also participated in Open Lab meetings with Iquitos, Satipo, and Lima, which allowed us to organize and conduct open workshops in the different labs. In these sessions, we were able to review the software necessary for the work, as well as the machines, materials, and instruments required for each activity. This experience strengthened coordination between nodes and allowed us to better understand the importance of planning and managing resources effectively in digital fabrication processes.

group work

The objective was to conduct laboratory safety training to understand and correctly apply the operating procedures for the machines and equipment. Additionally, we sought to familiarize ourselves with the machine's operation through tests involving descent, alignment, accessories, speeds, feeds, materials, and toolpaths. This ensured safe, precise, and efficient use during machining and manufacturing processes within the laboratory.

Introduction to Computer-Controlled Machining

The topic of Computer-Controlled Machining was new to me and the other members of my group. Thanks to the support of Evelyn Cuadrado, we were able to better understand the initial concepts. She provided us with a clear introduction, a practical example, and support in using the program, which facilitated our learning and allowed us to move forward with greater confidence this week. In addition, Cristian Loayza helped us with the laboratory safety talk, explaining the main safety rules and recommendations for the correct use of the machines and tools in the Fab Lab.

Group Work

The group work was conducted across different labs, beginning with a virtual meeting where we analyzed the week's requirements and organized the activities. During this meeting, we also shared information about the machines available in each lab, allowing us to identify the capabilities of each piece of equipment and define the tests we could perform based on the available resources. It was a very interesting experience, as there is a variety of machines and configurations, which gave us the opportunity to compare results, analyze differences in performance, and better understand how technical characteristics influence digital manufacturing processes.

Group Work

Computer-Controlled Machining

For this group assignment, we worked with a large-format CNC machine to understand the complete workflow of computer-controlled machining. The objective was not only to operate the machine, but also to evaluate the main variables that affect machining quality and safety, such as alignment, material fixation, spindle speed, feed rate, plunge rate, cutting depth, and toolpath strategy.

We used a ShopBot PRSAlpha 96x48 CNC router. The toolpaths were prepared in Aspire, and the machining process was executed using ShopBot3.

As part of our testing process, we fabricated a square test and a comb test to evaluate press-fit behavior, material tolerance, and joint adjustment. These test pieces helped us understand how tightly the joints fit and how the machine, the tool, and the material interact in real cutting conditions.

The square test had an outer size of 150 mm x 150 mm and an internal square cutout of 50 mm x 50 mm. The comb test had overall dimensions of 420 mm x 100 mm and included multiple slots with widths of 18.00, 18.25, 18.50, 18.75, 19.00, 19.25, 19.50, 19.75, and 20.00 mm. These variations allowed us to compare how the real material thickness and machining tolerance affected the final fit.

In both test pieces, we added dogbones in the internal corners and internal teeth/slots. These reliefs were important because the milling bit is round and cannot produce a perfect sharp internal corner. By adding dogbones, the internal joints became easier to assemble and the press-fit evaluation became more realistic.

The comb test reference used in our practice was adapted from the Fab Academy documentation of Silvana Espinoza, whose Week 7 page served as inspiration for this type of fit evaluation. We used that reference as a starting point and then adjusted it to our own machine, material thickness, and machining parameters.

Safety Training

Before operating the machine, we received a safety briefing from Jefferson Lados Villegas, Operational Laboratory Equipment Specialist. During this induction, we reviewed the personal protective equipment required before handling the machine and the material, as well as the safety conditions of the workspace.

The training included the mandatory use of personal protective equipment (PPE), identification of machine safety zones and floor markings, emergency stop procedures, the machine startup system, safe interaction with the control software and physical controls, and the importance of keeping the work area clean and clear before operation.

We were instructed to wear appropriate clothing and protection, including gloves, safety glasses, hearing protection, a helmet, and in some cases a lab coat or protective clothing, as well as closed shoes and suitable long clothing.

We also identified the machine’s emergency stop button, located next to the machine, and the startup key used to enable machine operation.

cDry chemical fire extinguisher available near the work area.

Marked safety line and controlled machine area.

Safe Workspace and Protective Measures

Before turning on the machine, we checked that the workspace was clear, the sacrificial bed was clean, there were no objects interfering with the machine path or operator movement, the safety area was clearly marked, the required PPE was being used, and a dry chemical fire extinguisher was available nearby.

This step helped us understand that safe CNC machining depends not only on the machine itself, but also on the preparation of the environment and the awareness of the operator.

Machine, Material, and Tooling

The machine used in this assignment was a ShopBot PRSAlpha 96x48.

For the test, we used a piece of plywood with a thickness of 18 mm and approximate dimensions of 330 mm x 560 mm. The material was fixed to the sacrificial bed using screws in order to avoid movement during machining.

The cutting tool used was a 6 mm End Mill, 2 edges, up/down cut.

ShopBot PRSAlpha 96x48 used during the assignment.

Material placed and fixed on the sacrificial bed.

Test Setup and Machining Parameters

The first test was carried out on a scrap piece of plywood available in the lab. This allowed us to perform the necessary checks while using a material with dimensions suitable for the design.

Tool Parameters

• Tool type: End Mill
• Diameter: 6.0 mm
• Flutes: 2
• Cut type: Up/Down cut
• Pass depth: 3.0 mm
• Stepover: 3.0 mm (50%)
• Spindle speed: 15,000 rpm
• Feed rate: 4500 mm/min
• Plunge rate: 1200 mm/min
• Tool number: 1

Because the board thickness was 18 mm and the pass depth was 3 mm, the machining required approximately 6 passes to go through the material.

What We Tested

• Material fixation: the plywood board was fixed to the sacrificial bed using screws.
• Initial zeroing in X, Y, and Z: we first set the machine reference after placing the material on the bed.
• Recalibration after fixation: after placing the board and doing the initial setup, we fixed the material with screws and then calibrated the machine again, especially on the X and Z axes.
• Alignment: we checked that the board was properly placed and aligned relative to the machine bed.
• Feeds and speeds: we observed how spindle speed, feed rate, and plunge rate affect the cut.
• Depth per pass: the cut was divided into multiple passes.
• Toolpath strategy: we used a 2D Profile Toolpath and considered tabs.
• Press-fit testing: we produced a square test and a comb test. The square test measured 150 mm x 150 mm with an internal square of 50 mm x 50 mm. The comb test measured 420 mm x 100 mm and included slots from 18.00 mm to 20.00 mm in increments of 0.25 mm.
• Dogbone geometry: we added dogbones in the internal corners of the square test and in the internal teeth of the comb test.
• Tabs: tabs were added in both tests to keep the internal pieces attached during machining and prevent them from moving or flying out while cutting.

Workflow

1. The vector design was created in a CAD environment such as Fusion or Rhino.
2. The design was exported and imported into Aspire.
3. In Aspire, the material dimensions and the origin point were configured.
4. The cutting tool was selected as a 6 mm end mill.
5. The main machining parameters were defined: pass depth, stepover, spindle speed, feed rate, and plunge rate.
6. A 2D Profile Toolpath was generated, selecting the cutting side and adding tabs where necessary.
7. Dogbones were added to the internal corners of the test pieces to improve internal fit.
8. The toolpath was simulated in Aspire to verify the process and detect possible errors before machining.
9. Once verified, the file was exported for ShopBot machining.
10. The plywood board was placed onto the CNC machine bed.
11. An initial machine reference was set.
12. The board was fixed with screws to the sacrificial bed.
13. After fixation, the machine was calibrated again, especially on the X and Z axes, to ensure correct positioning before machining.
14. The tool was installed in the spindle.
15. The file was loaded into ShopBot3 and the cutting process was started.

Machine detail before machining.

Results

Press-Fit Tests

As part of our testing process, we fabricated a square test and a comb test to evaluate press-fit behavior, material tolerance, and joint adjustment.

The square test had an outer size of 150 mm x 150 mm and an internal square cutout of 50 mm x 50 mm. The comb test had overall dimensions of 420 mm x 100 mm and included slots from 18.00 mm to 20.00 mm in increments of 0.25 mm.

Square Test

The square test was used to evaluate the internal fit of a smaller square inside a larger frame. We added dogbones in the internal corners to compensate for the round shape of the milling bit. We also added tabs so that the internal part would remain attached during machining and would not move or fly out during the cut.

Square test design in Aspire with dogbones and tabs.

Square test result to verify the accuracy of the internal square cut.

Comb Test

The comb test was used to compare different slot widths and identify the best press-fit according to the real material thickness and machining tolerance. This design included slots of 18.00, 18.25, 18.50, 18.75, 19.00, 19.25, 19.50, 19.75, and 20.00 mm.

We also added dogbones in the internal teeth to compensate for the round shape of the milling bit, and tabs were included to keep the internal parts stable during machining and prevent them from moving or flying out during the cutting process.

Comb test design in Aspire with slot variations, dogbones, and tabs.

Comb test used to evaluate press-fit tolerance with slot widths from 18.00 mm to 20.00 mm.

What We Learned as a Group

As a group, we learned that large-format CNC machining is not only about sending a file to the machine. It requires preparation, safety awareness, correct machine setup, suitable cutting parameters, and proper fixation of the material.

We understood that safe operation begins before the machine starts, toolpath simulation is essential to prevent mistakes before cutting real material, zeroing the machine correctly is one of the most important steps in the process, and recalibration after fixing the board can be necessary to maintain accuracy.

We also learned that feeds, speeds, and pass depth directly affect cutting quality, machine stability, and tool performance. In addition, press-fit tests are very useful for understanding material tolerance and joint behavior.

Dogbones improve internal fit in CNC-milled joints, and material behavior also matters because plywood can produce rough edges and sometimes requires finishing after machining.

Conclusion

This group assignment allowed us to document and understand the workflow of large-format CNC machining using the ShopBot PRSAlpha 96x48. Through this exercise, we practiced safety procedures, prepared material and toolpaths, configured machining parameters, and executed a successful test cut on plywood.

The experience helped us connect digital design with physical fabrication and gave us a better understanding of how machine setup, parameter selection, material behavior, and safety practices influence the final result.

The use of the square test, comb test, and dogbone-adjusted joints made the assignment more useful for evaluating real press-fit conditions, which is valuable for future CNC construction projects.

Reference

The comb test used in this assignment was adapted from the Fab Academy Week 7 documentation of Silvana Espinoza and then adjusted to our own machine, material thickness, and machining parameters.

Individual Task

Create (Design + Milling + Assembly) Something Big

This was one of the tasks that allowed me to solidify some ideas based on real-world experiences we have observed. From a design perspective, I wanted to find a way to support artisans and entrepreneurs who participate in fairs to offer their products.

They generally use tables to display their products, but these tables are often solid, heavy, and difficult to transport. In addition, they do not always allow the products to be displayed clearly and attractively.

For this reason, I proposed the design of a product display that is easy to assemble and disassemble. The idea was to create a system with a simple structure that allows it to be transported easily to different fairs.

This design is intended to be assembled without the use of bolts or screws, using only a press-fit system, which allows the pieces to be joined through friction and precise fitting.

The goal is to continue developing this concept of mobile furniture that responds to the realities of artisans and entrepreneurs who constantly travel to different parts of Peru. Just as the Fab Lab promotes digital fabrication in different spaces, artisans could also take these displays to different places and organize traveling fairs anywhere.

Using a simple, portable, and functional piece of furniture can help improve the presentation of their products and support better sales opportunities during fairs and exhibitions.

fairs for entrepreneurs and artisans.

Concept and Proposal

Before beginning the digital design, I reflected on the type of object I wanted to create, how it should function, and who would use it. My goal was to design a structure that was functional, stable, safe, and easy to assemble.

First, I created a sketch to visualize the overall shape, the pieces, and the structure of the display. This initial step helped me better organize the idea and understand how the different elements could fit together before moving on to the digital design.

fairs for entrepreneurs and artisans.

Design in SolidWorks

Starting with the initial sketch, I began developing the design in SolidWorks. I started working on the plan view to define the main dimensions and the layout of the structure, and then moved on to the 3D model to visualize how the different pieces would be joined.

During the 3D modeling, I was able to analyze the connections between the pieces, the joints, the gaps, and the angles necessary for the products to be displayed properly. This process was important to ensure that the structure was stable and functional.

The design process was not simple, as it was necessary to consider several factors, such as material thickness, material type, finishes, press-fit joints, and the assembly system. All of these aspects were important to ensure that the final design could be manufactured correctly using the CNC cutting process.

Design in SolidWorks.

Design in SolidWorks.

Design in SolidWorks.

Machining with Aspire

To prepare for machining, we open a new file in the software and locate our .DXF file, previously exported from the design program. This file is imported into Vectric Aspire and adjusted to the format and dimensions of the cutting area. Next, we establish the machine origin points, which will serve as a reference for machining.

Once the design is loaded, we select all the vectors we wish to machine and use the Profile Toolpath option. At this stage, we choose the cutting tool, in this case a 6 mm milling cutter, and configure the machining parameters such as depth of cut, feed rate, and spindle speed. After defining these parameters, we confirm the operation so that the software generates the machining toolpath.

Before performing the actual cut, we run a simulation of the toolpath to verify that there are no errors and to ensure that all parts will be cut correctly. Once the process is validated, we export the machining file in G-code.

For this process, we use the NC Studio post-processor in millimeters (.tap) and save the generated toolpath for use on the CNC machine.

CNC Milling

Next, we open the NC Studio software and load the file containing the generated code. We place the OSB board on the machine bed and secure it firmly with screws to prevent any movement during the cutting process.

We then position the tool and set the origin of the X, Y, and Z axes (machine zero) to ensure the machining is performed in the correct position.

Once the cutting process is complete, we carefully remove the pieces. We then proceed with the assembly, using a rubber mallet to fit the pieces together through the press-fit system. This step must be done carefully to avoid damaging the edges of the material and to ensure that the joints are firm and properly fitted.

Machining with Aspire

Machining with Aspire

Machining with Aspire

CNC Milling

CNC Milling

Design in SolidWorks.

Design in SolidWorks.

final design.

Conclusions

During this activity, I was able to understand and apply different stages of the digital manufacturing process using CNC. First, I learned to design a 2D CNC cutting project using Corel Draw, which allowed me to correctly prepare the vectors necessary for machining.

I also learned to configure and generate machining toolpaths in Vectric Aspire, defining important parameters such as the cutting tool, depth of cut, feed rate, and spindle speed. This step was fundamental to ensuring that the digital design could be correctly transformed into machine instructions.

Furthermore, I gained experience operating a CNC milling machine, understanding the material preparation process, table clamping, setting the reference axes (X, Y, and Z), and performing the cut safely.

Another important lesson was understanding the importance of planning and organization throughout the entire design and machining process. Good planning allows for optimizing material usage, reducing cutting time, and preventing errors during manufacturing.

Ultimately, this experience allowed me to better understand the relationship between digital design and physical manufacturing, as well as the importance of considering aspects such as material thickness, press-fit joints, and the assembly process from the design stage. These lessons will be very useful for the development of future digital fabrication projects.