Computer-Controlled Cutting

Group Assignment

Characterize your laser cutter's focus, power, speed, rate, kerf, and joint clearance
Document your work (individually or in group)

Individual Assignment

Design, laser cut, and document a parametric press-fit construction kit, which can be assembled in multiple ways. Account for the laser cutter kerf.

Learning Outcomes:

Demonstrate and describe parametric 2D modeling processes
Identify and explain processes involved in using the laser cutter
Develop, evaluate, and construct the parametric construction kit

Have You:

Linked to the group assignment page
Explained how you parametrically designed your files
Documented how you made your press-fit kit
Included your hero shots

Vinyl Cutting

Individual Assignment

Cut something on the vinyl cutter

Learning Outcomes:

Identify and explain processes involved in using the vinyl cutter

Have You:

Documented how you made your vinyl cutting
Included your original design files
Included your hero shots

Tools Used

Laser cutter made during machine design week
Silhouette Cameo

Software Used

Files

Press-fit construction kit: Zip file with the SolidWorks file, DXF file, and laser cutter G-code
Test Files

Hero Shot

Warning

Wear safety glasses, make sure you know where and how to operate the fire extinguisher, and never leave the laser unattended!

Risk of Fire

The laser cutter is a machine that can catch fire if not properly monitored. If everything is working correctly, it won't, but if there is a failure and the laser stays in the same place or if the air assist stops working, there is a high risk of fire. For this reason, never leave the laser unattended.

Fire Safety

Fire Extinguisher

Laser Radiation

The laser beam can blind you or burn your skin in nanoseconds. For this reason, never operate it with the lid open, and always wear the safety glasses for the type of laser you are using.

Laser Safety

CO2 laser cutters typically have a wavelength of 10,600 nm. In our lab, these are the correct glasses.

CO2 Laser Glasses

Diode laser cutters are typically in the 445-455 nm wavelength range. In our lab, these are the correct glasses (they cover 200-550 nm).

Diode Laser Glasses

Introduction

In this assignment, I was going to use a 3D printer I designed and made, which I then upgraded with a 2-watt diode laser. However, I ended up designing and making a CO2 laser cutter as I did not want to finish this course without such a machine in my lab. I am really happy with my machine. It is showing amazing results even as a DIY machine.

I will be testing its capabilities and pushing it to its limits to better understand its capabilities and limitations.

On the vinyl side of the assignment, I will be using a Silhouette Cameo and documenting its results.

3D Printer with Carbon Fiber Body 3D printer I designed and made with a milled carbon fiber body

3D Printer with Laser Head The printer now with a 2-watt diode laser head attached to it

DIY Laser Cutter Laser cutter I designed and made in Mechanical Design, Machine Design

Group Assignment

Visit the group assignment page for other assignments. This week's group assignment I am doing by myself, as I am alone in the lab.

Characterization of My Laser Cutter

Work area: 400 x 290 mm
Height: 150 mm
Laser power: 50 W

Focus and Kerf
Image extracted from the Laser Cutter Focus video by makestuffnow!

The lens I use in my laser is a 20 mm diameter lens with a 50.8 mm focal length. This means I should keep the height from the lens around that measurement.

It would be a challenge to measure the focal distance every time. For this reason, I designed the ramp below. This will allow the laser to trace a line from the highest point of the ramp (0 mm from the tip of the laser) to the lowest point of the ramp.

Design files for the focus ramp here

The result from the test is that I should use a distance of 5 to 7 mm from the top of the material to the tip of the laser head.

Laser cut result from the focus test

With the trace done, I started measuring the most focused area of the trace with a caliper and a square.

The result is a range from 5 to 7 mm.

To easily measure the optimal distance I found, I designed small steps of 1 mm, starting at 3 mm and ending at 8 mm.

I then laser cut it.

Placing the nozzle on top of the desired height gives a consistent measurement across the surface of the material.

Measuring the kerf was simple. I used the previous template and the hole left by the cut. The difference is twice the kerf, the thickness of the material removed by the laser beam.

The inside measurement was 8.1 mm.

The outside measurement was 7.9 mm, which means the kerf is 0.2 mm / 2 = 0.1 mm.

I really like the fact that it fits perfectly!
Power and Speed
Original SVG used here

The power test above was done with a speed of 5000 mm/min on 2.7 mm plywood. The power I chose as the most suitable for this speed is 50%.

The speed test above was done on 2.7 mm plywood, with the power set at 60%. Even with the low power, the laser was able to cut at almost all the speeds tested. To be on the safe side, I would choose to cut at 5000 mm/min with the power at 60% for this thickness of plywood.

Press-Fit Construction Kit

For this assignment, I will use 2D design from SolidWorks. This is done within the sketches. SolidWorks is a parametric design tool, able to dynamically change its features with the change of a variable.

I started by creating a sketch. I then drew a triangle.

Triangle Sketch

Next, I started creating global variables. While adding dimensions, I simply typed the equals sign "=" and then named the variables. Next, I confirmed the creation of the global variable.

Global Variables

I kept adding more features to the sketch, adding parameters to each measurement.

Sketch Features

Next, I created a pattern with the desired feature that will be the connection of the piece.

Pattern Creation

In this panel, I am able to edit each variable, changing it and dynamically changing the model.

Variable Editing

I added a little fillet here to allow a smooth coupling of the parts.

Fillet Addition

I proceeded to create formulas. This will allow me to change the opening by changing one variable, and it will take into account the kerf size.

Formula Creation

Next, I prepared the kit for exporting as a DXF file.

DXF Export Preparation

In SolidWorks, in order to export a sketch, keep it open, then click on Save As and do not rebuild, then choose the format, in my case DXF, and finish the export process.

DXF Export

In LaserWeb, add the document. Next, drag the added document to the gray area below.

LaserWeb Document Addition

After dragging the file, a dialog with configurations will open. The software sometimes won't prevent you from creating invalid G-code. This means if some parameters are filled up, it will not warn you about them.

For this job, since it's a cut, I used one of my presets with the speed at 4000 mm/min, power at 80%, and segment at 0.1.

LaserWeb Configuration

Next, I positioned the object using either the arrows or the coordinates.

Object Positioning

Here I show that I ended up multiplying the triangles in SolidWorks and then reopened the file.

In this picture, it is also possible to see, at the top middle, the image from the web camera that is positioned on top of the laser, so I don't need to keep my eyes on it. Even though I wear protective glasses, I still prefer not to look at the laser while it is still without a cover.

Web Camera Setup

The laser cuts it very well.

I then removed it from the machine and piled it up to start inspecting and assembling.

Just a pile.

Kit Pile

I then started the assembly, and it fits perfectly.

Vinyl Cutting

The vinyl cutter we have in the lab is the Silhouette Cameo 3. It's a nice, affordable, easy-to-use vinyl cutter.

Lab's Silhouette Cameo 3

It comes with the software Silhouette Studio.

Screenshot of the first screen when you open Silhouette Studio

Learning Outcomes:

Identify and explain processes involved in using this machine.

Creating the File
1. Selecting a File from the Library
  As a warm-up, and because we were near Halloween, I decided to cut something my kids could use.
  
  Image of the Studio library
  
  I chose the bat from the library.
  
  Outline of the bat chosen from the Studio's library
  
  After double-clicking, the bat gets inserted in the middle of the work area.
  
  Then, using Ctrl+C and Ctrl+V, I copied and pasted the bat several times.
  
  I then selected all the pasted bats.
  
  With the drawings selected, it is possible to align them uniformly.
  
  I then selected the vinyl size.
  
  I then pasted some more bats again and started setting up the job. This machine is capable of automatically setting the thickness of the material, but the AutoBlade option must be selected.
  
  I then aligned the vinyl and lifted the roller that drags the material.
  
  Using the screen, I fed the material in a little bit.
  
  At this point, I could either connect a USB cable directly to the machine or use a USB flash drive.
  
  I pressed start, and in minutes the bats were cut.
  
  For a project as simple as that, it is sufficient to just peel the adhesive off the protective paper and stick it everywhere!

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