Objectives

Group assignment:-do your lab's safety training test runout, alignment, fixturing, speeds, feeds, materials, and toolpaths for your machine.

Individual assignment make (design+mill+assemble) somethingbig (~meter-scale) extra credit: don't use fasteners or glue extra credit: include curved surfaces.

Group assignment

In group assignment we learned about safety measures. We made a jig to test fit. We learned to operate shopbot cnc machine, its speeds, feeds, material and toolpaths.Key aspects of safety training include using Personal Protective Equipment (PPE), following safe behavior practices, conducting pre-operation checks, and adhering to machine operation guidelines. Maintaining a clean workspace, preparing for emergencies, and continuously improving safety procedures further contribute to a secure and efficient working environment.

group assignment page

7.COMPUTER CONTROLLED MACHINING

CNC (Computer Numerical Control) machining is a precise and automated manufacturing process where pre-programmed software controls the movement of machines and tools. It uses a specialized language called G-code to dictate cutting speed, feed rate, and tool paths, enabling machines to cut, drill, grind, and shape materials with high accuracy. CNC machining relies on CAD (Computer-Aided Design) and CAM (Computer-Aided Manufacturing) software to generate instructions, allowing for the efficient production of complex parts from materials like metal, plastic, and wood. This process enhances precision, reduces manual labor, increases efficiency, and lowers production costs, making it essential in industries such as aerospace, automotive, and manufacturing.

Designing a coffee table

This week, I wanted to try to make a coffee table. I drew an intial skecth and designed a 3D model in fusion.I made a parametric design.

Using the parameters I designed the table and changed the appearence. I didn't wanted a plain table top. So I added a voronoi sketch generator in add tool in fusion. Utilities-> add ins-> voronoi. First we need to download the script and create a folder.

Useful link

Using emboss it is then added to the table top.

Before cutting it in the workpiece, the model was lasercut in a cardboard.I used a ratio calculator to scale down the design inorder to make a small model of the same.

The design is assembled projected and exported as dxf and opened in Inkscape. The height of the canvas is adjusted with the value from ratio calculator in inkscape.The design underwent lasercuting.The result came out pretty well.

Mistakes:

When I projected the sketch, the table top sketch got projected two times which resulted in two passes in laser cutter.
After lasercutting it is found that the spacing between two patterns is very thin. In cardboard the structures will break. I couldn't engrave it as I was planning to add pockets in the bottom part of table top.

Milling

I continued my designing with out voronoi patterns.I exported the file to vcarve

VCarve

VCarve software by Vectric is CAD/CAM (Computer-Aided Design/Computer-Aided Manufacturing) software used for creating 3D carvings from 2D images.

Initially I measured the thickness of plywood and the average value was taken as 17.4mm. From group assignment the clearence value was found as 0.2mm

Using clamps and nails the carboard is fixed in place

Open VCarve the length, width and thickness values are entered.I opened my file in it. Dogbone was added.In tooldata base, selections were made accordingly.

I wanted to create pockets in the base of table top. Pocket toolpath is selected. To cut, 2D profile tool path is selected.To minimize space wastage the parts are arranged in fusion before exporting.

After making necessary changes the file is fed to shopbot software.

We have to calibarate x,y and z axis, afterwhich the start button in the window is pressed to operate

Mistakes: Initially when the program is fed, a window opens. It says to start spindle and click OK. Before starting the spindle I clicked OK.Friend pushed emergency button.If we operate before starting spindle the spindle will break.

Assembly

After CNC cutting, post-processing involves enhancing or modifying the cut pieces for functional or aesthetic reasons. This can include surface finishing, cleaning, deburring, or applying coatings like paint.Then assemble the parts together.Here is the final result.

mistakes:Because of the variation in thickness, someparts didn't came as clean cut.

The table was plain and I wanted to continue with my Idea of adding patterns in it. Instructors told me that it is possible to engrave the patterns using laser cutter.

A test cut was made in a small piece of plywood

From analysing the test cut I chose power as 90%, speed 20 and number of passes as 2.I cut the outerpart of the table in cardboard for reference and placed the table top inside it.

And the result.

In molding and casting week, I plan to add resin and give a it a final finishing.

Conclusion

This week’s work on computer-controlled machining provided valuable hands-on experience with CNC operations, safety protocols, and design iteration. From initial sketching to final assembly, I explored parametric design, laser cutting for prototyping, and CNC milling for fabrication. The process highlighted the importance of precise measurements, toolpath optimization, and troubleshooting errors, such as unexpected double projections and material thickness variations. Despite some challenges, the final coffee table successfully came together, with additional engraving added for aesthetics. This project reinforced my understanding of digital fabrication workflows and practical problem-solving.

files

Design files