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Computer Controlled Machining

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) something big (~meter-scale)
Extra credit: don't use fasteners or glue
extra credit: include curved surfaces

Design Process

Fusion 360

Chair Design
Slicer for Fusion 360
Cat Home Design

Testing

CNC Machining

ShopBot PRSalpha

Safety Measures
Machine Specifications

Cutting

Group Assignment

Click here: Do your lab's safety training

Test runout, alignment, fixturing, speeds, feeds, materials, and toolpaths for your machine

Design Process

During week three I had come across a parametric chair which I really liked. So I thought of designing that first and see how it goes.

Fusion 360

Fusion 360 is the go-to 3D designing software for me. The workspace and the workflow is very conveinent and easy for any beginner. I started 3D designing during Fab academy and Fusion 360 has been the best for me. Although, I'm still learning its full potential.

Chair Design

I wanted an egg shape to start off with my design, So I tried to get the shape. Then I trimmed off the remaining lines.

Then I trimmed off the remaining lines. Here's the egg shape.

I revolved the shape and revolved another egg shape for the seating and used boolean operation.

I cut off the bottom to get the shape like a bean bag.

Slicer for Fusion 360

I came across Slicer via various YouTube tutorials I had watched for furniture design. It seemed like an easy tool since it would slice any solid object and give the DXF file with all slots. Unfortunately, it is not supported by Fusion 360 anymore so I had difficulties to run it. But after a few tries, it opened.

I imported STL file of the chair design and gave construction technique as interlocked slices. I changed the height to 10 cm, since I wanted to make a prototype in cardboard first.

This software is very conveinent since it gives the assembly steps and as well as the plans.

I exported the DXF file of the plans to cut in cardboard.

Cat Home Design

My FAB mate, Kalyani shared this design of cat home and I really liked it. I thought of designing it incase the chair wouldn't work out.

I sketched it, I tried to arrange it in the plywood sheet to see if the material was enough. Few parts were missing and the material wasn't enough for this design.

I tried to make a few changes by removing few circles and the joints. Alas! The material still wasn't enough.

After a few iterations with my instructor, we reached this design. It looks similar but the radius of each circle is optimised for minimum material.

The design

Testing

Before Machining, it is important to test a prototype of the design to check if everything works out the way I planned it. I'll be doing a scale down version of the original design in Zund of the chair and the cat home.

The chair parts has been all cut.

Success! The chair has been assembled successfully.

But...

Even though chair was a success, the slicer couldn't give me a proper plan to cut in plywood. I tried different options but either the plans it gave me required a lot of material or for the optimised material, the shape wasn't received as expected.

So I had to test the cat home. Here's the cutting.

Here's the assembled version. Due to flexibility of the cardboard, the joints weren't fitting properly. Even after using a masking tape, the parts weren't fitting so my instructor helped to use thread so that one part stays strong. Likewise, 2 joints were threaded and assembled.

Here's the cat home (currently a wolf home)

Both of the designs together

CNC Machining

Now that I have completed the designing and testing, next step is the machining procedure.

ShopBot PRSalpha

The ShopBot PRSalpha is a top-tier 3-axis CNC machine renowned for its precision and reliability in woodworking. Its robust construction ensures stability and accuracy, even when handling intricate designs. Equipped with a range of high-performance spindle options, it effortlessly tackles various materials, from wood to non-ferrous metals. Intuitive software facilitates easy project design and programming, making it accessible to users of all skill levels. With its versatility and unmatched performance, the PRSalpha is the go-to choice for hobbyists, small businesses, and large-scale manufacturers alike, elevating woodworking projects to new heights with its exceptional precision and efficiency.

Safety Measures

Safety is paramount when operating your ShopBot CNC machine. In case of an emergency, the SPACEBAR on your computer keyboard functions as an immediate Panic/Stop/Halt button, halting the tool's movement instantly. Additionally, your ShopBot is equipped with a physical STOP Button, conveniently placed on the tool, which stops movement and, on a PRSalpha ShopBot or Buddy, cuts power to the spindle/router.

Read the manual thoroughly to familiarize yourself with the tool and its operation. Also, review manuals for the router/spindle mounted on your ShopBot.
Practice operating the ShopBot using the computer and ShopBot Control Software before engaging the router/spindle.
Prior to loading, positioning a workpiece, or adjusting the tool's position, always turn off the router or power tool. Avoid changing router bits or cutters without unplugging the power tool or ensuring it won't accidentally activate.
Secure the workpiece firmly to the work surface before cutting and maintain a safe distance from the tool during operation to avoid injuries from flying debris or broken cutters.
Never operate the tool when fatigued to maintain alertness and prevent accidents.
Wear eye and ear protection at all times when operating the ShopBot to safeguard against potential hazards.
Never leave the tool unattended while it's running to prevent unexpected cutting errors or workpiece slippage. Always maintain supervision during operation for maximum safety.

Machine Specifications

XY Move Speed (with full cutting force): Variable, max. 18.2m/min.
Z Move Speed (with full cutting force): Variable, max. 9.14m/min.
XY Positioning Speed: Variable, max. 45.7m/min.
Z Positioning Speed: Variable, max. 22.86m/min.
Step Resolution: 0.010mm
Linear Cutting Force: Approximately 68 Kg
X and Y Axis Drive System: Rack and Pinion
Z Axis Drive System: Rack and Pinion
Input Voltage: 220v single-phase, 230v 3-phase and 380/460V 3-phase power options are available, depending on tool and configuration.
The PRSalpha requires a fused disconnect installed by a licensed electrician. Spindle may require 3-phase.

Cutting

Design Files

Files

Chair STL
Chair DXF
Cat Home DXF