Our group task was to determine the optimal laser cutter parameters and measure the cut width (kerf). For vector cutting,
we can adjust parameters such as focus, speed, power, and frequency. For my work on cardboard using the Epilog Mini 18 (40W),
I used the following settings:
Speed: 100%
Power: 60%
Frequency: 500 Hz
Kerf: 0.375 mm
Focus: On top of the cardboard
Speed, power, and frequency can be adjusted via the cutter's software. Speed determines how fast the cutter moves,
while power controls the laser's intensity, higher power allows cutting through thicker or denser materials.
Frequency defines the number of pulses the laser generates per inch of its trajectory.
Kerf refers to the width of material removed by the laser, influenced by the nature of the laser beam.
To achieve an optimal cut, the laser must be properly focused. Since most of the laser’s energy is concentrated at the focal point,
focusing on the top or middle of the material is ideal. To focus the laser cutter, a metal gauge of a specific length is used to
set the correct focal distance (fixed based on the lens type). The tip of the gauge should slightly touch the working material.
This distance can be adjusted by either moving the material (as in our case) or the optical lens.
Yoyo CAD modeling
First task of our second week was to try some CAD modeling to get familiar with the software. For this purpouse I have decided to
choose some object, that would allow me to work with as many Fusion 360 features as possible. For my work, I have chosen my yoyo.
Firsly, I have decided to make my measurements. I have measured each breakpoint diameter of the yoyo from the tom and from the bottom using
caliper. For the depth measurement, I have used a piece of cardboard and marked distance from each brakepoint to the edge of the yoyo. I was
able to measure those mark with ruler quite easily.
Parameters from largest to lowest
Top diameters (opposite side of the joint): 55 mm, 52 mm, 44 mm, 35 mm, 15 mm
Bottom diameters (on the side of the joint): 55 mm, 50 mm, 36 mm, 22 mm, 13 mm, 6 mm
Side profile (from the edge opposite from joint to each breakpoint): 20 mm, 16 mm, 7 mm
Depth (from the edge to each breakpoint): 15 mm, 9 mm, 3 mm, 1mm
After getting those parameters, I have defined them inside the Fusion using parameters feature. With that, I was able to sketch cross section of half
the yoyo using sketch tool. Every line was straight line during sketching, after all parameters set through constrains, those curve lines were created by using Fit Point Spline tool.
After that, the body was creating using Revolve tool and copied to create the second half using Pattern tool.
To create ball bearing I have used Bottom diameter parameters (6 mm and 13 mm), to specify parameters of this circular object with a hole inside with width of 5 mm. I have also measured diameter
in the middle of the bearing, that is different because of a small dent (12 mm). I have created space for balls of the bearing with diameter of 1,25 mm.
To create cast of the ball bearing, I have used, again, Revolve tool. To create balls of the bearing, I have 3D modeled them using Sphere tool and duplicated them alongside the bearing
using Circular pattern tool, that duplicated them 20 times.
Final work looks like this, with comparison to template yoyo.
Sticker
One of the homework assignments for Week 2 was to design a vector graphic, which would later be used as a template for a sticker.
The first step was to create our own vector image. Software like Inkscape can be used for this, but I chose Fusion 360 instead,
as I wanted to familiarize myself with the software that will be used extensively later in the course.
I decided to create a colorless version of the FC Barcelona crest. My first step was to look for inspiration online.
The design I used as my reference was this
FC Barcelona crest,
which features a black-and-white design that works well as a sticker.
Due to its complex shape, I decided to use the Canvas tool to import the image into my project.
Once imported, I created a sketch over the canvas, allowing me to trace the design accurately.
Creating the badge sketch
To create the curved sections, I used the Fit Point Spline tool, which allows for drawing smooth curves by
interpolating through selected points (which can be predefined using the Point tool).
While this tool is great for generating precise curves, using too many points can result in an unnatural shape.
Therefore, it’s best to use as few points as possible for a cleaner design.
I started by creating only half of the badge outline since the other half could be mirrored easily using **the Mirror** tool.
The internal elements of the crest were more challenging but were created using a similar approach.
The cross and stripes were straightforward, but the most difficult part was the ball, which I constructed manually using circular
geometry pattern, estimating the proportions by eye.
After creating the sketch, by clicking Finish sketch and using Extrude tool (1 mm high), I was able to create a 3D object of the badge.
After that, I created a new, clean sketch by adding an **Offset Plane** 10 mm above the badge body in the **Construct** section and then starting a new sketch.
Using the **Project** tool, I was able to obtain clear 3D object outlines by selecting all the bodies and projecting them onto the sketch.
Finally, the sketch could be exported as a **.DXF vector file** by right-clicking the projected sketch in the sketch list and selecting **Export DXF**.
Sticker cutting
The vector image was intended to be sent to the vinyl cutter, but unfortunately, the software Silhouette Studio couldn't load my .DXF file correctly.
Instead of the FC Barcelona badge, I ended up with an interesting, funky design but it didn't look as intended. I wasn't the only one that had issues like this,
it seems that it could be resolved by exporting it through some web tools for vector images, but I didn't have time to fix that.
Because of that, I ended up without the sticker. I am planning to fix the vector image and try again in following weeks.
3D Puzzle
The second homework of this week was to design and create our own puzzle. Our puzzle pieces would be later cut inside using a laser cutter in the lab.
The pieces would be cut from cardboard. The goal of the homework is to get familiar with CAD software such as Fusioon 360 and with a laser cutter, it's use,
parameters, workflow and necesary security measures.
Mclaren MP4/4 puzzle
I have decided to create my own desin of 3D puuzle, more specifically 1:40 model of F1 car Mclaren MP4/4 from 1988. I wanted to create
a model of F1 car and this legendary car with it's more of a box-like shape was ideal candidate.
I wanted to make it as precise as possible without paying any money for exact parameters of the car.
Most of my inspiration came from this 3D model on Sketchfab
and side profile on the-blueprints.com .
Basic info such as car length, width etc. was taken from f1.fandom.com
Designing the model
I have used the Fusion 360 for the modeling. The most important part of this project was to create parameters for the model and create puzzle pieces around them.
For my work, I have used these parameters:
Wheel diameter: 18 mm
Wheel base: 71,875 mm
Car width: 53,35 mm
Car length: 117 mm (a bit longer than 1:40 scale)
Car height: 23,5 mm
Non-fixed cardboard width: 2,4 mm (for 2,5 mm cardboard)
Because of this parameters, I was able to create scalable pieces. When creating a piece, constrains can be added, and one of them are dimensions of the object (numerical or parametric value).
By doing that I was able to change material width and puzzle scale with one click of a button.
Designing pieces
For my design I have decided to create 10 different pieces for my puzzle that will be helt together by slot joints.
Wheel
Every car, of course, need wheels. For my model I have decided to create wheels with diameter of 18 mm with slot of
cardboard width taht cuts to the middle of the wheel
Main body
This is the backbone of the model, as it shapes the body of the car. The driver's cockpit starts in the middle of the car.
The front fourth of the car's length forms the nose, and the front window occupies 1/8 of the car's width.
The bottom dents connect different parts of the car's body and the wheels. The slots on the sides serve as connections to the axles, linking the wheels to both the Main Body and the Side Body.
The two middle slots on the bottom connect the Main Body, Side Body, Side Profile Long, and Side Profile Short.
The front slot connects the three middle parts and the front wing.
The rear axle is positioned approximately one wheel radius away from the back of the car. The front axle is located 1/4 of the car's length from the front.
The two middle slots, which hold the car's body together, can be placed anywhere the user prefers, as long as their positions remain consistent across all body pieces.
Side body
The Side body mimics Silhouette of the Main body, with sligthly lower height (0.8 of the car height), to capture curvature of the car.
The slots in the bottom must be same dimensions as the Main part. Also the slot for spoiler in the back is added.
Side profile long and short
These parts represent the sidepods of the F1 car. The long part is slightly longer than the short part with the longer side heading to the back of the car.
Both of them contain two slots that connect, through the Body Holder part, to the Main and Side Body parts.
As you can see, they are more box-shaped compared to the sidepods in newer F1 cars.
Axle
The axle part holds together Main and Side body part with wheels. The width of the part is same as wheel base parameter and the height
corresponds to the radius of the wheel. To capture tire width, two slots on each side are designed for the joint to the wheels. Three middle slots on top
are there for the connection with said body parts.
Body holder
Unlike Axle, the body holder only connects to the car body and side profile parts. It is also narrower (corresponds to car width parameter).
Going from the middle to the side, the slots are designed for: 1. Main body part, 2. Side body part, 3. Side profile long, 4. Side profile short.
It is also wheel radius tall.
Spoiler and front wing
The narrow spoiler is connected to the back of the Side body parts, the front wing (same width as car widt) is connected to the fron of Main and Side body parts.
In the bottom of the Front wing part, you can see slots for the Front wing Side pieces.
Front wing side piece
Front wing side pieces proportions are pretty much estimated by an eye. The key part is to be slightly wider than front wing and that the curvature on the left
copies the wheel curvature.
Final model
All assembled by using align tool in Fusion 360, the model corresponds to the template quite well. By being able put together the model using software, I was able to
check if everything is alright before cutting. For example, I wasn't satisfied with the wheel parameters after assembling the model using the software,
so I adjusted parameters before sending the final design to the cutter with ease.
Laser cutting
After completing the design, the outline of the pieces must be saved as a vector image. It is possible to extrude and project the object outlines to the new sketch
and export it the same way as done with the sticker design.
We used laser cutter Epilog mini 18 in our lab. It is 40W CO2 laser used for cutting and
engraving. For us, it is desired to cut this week. Before starting the cut, it is needed to focus the laser accordingly, in our case when cutting to the cardboard, we focus the laser on top of the cardboard.
After rhar, we can export our vector design to the computer connected to the cutter and set desired parameters. For vector cutting, there is speed, power and frequency. Firstly I used 100% speed, 50% power and 500 hz frequency
for my cardboard pieces. It struggled to cut through some of them, so I have increased the power to 60% in the end. After everything set up, you can place material inside the cutter.
If you don't close the lid, the laser is replaced by weak laser pointer, thus checking correct cutting path. To enable vector cutting, you have to set line width to at least 0,02 mm.
If you don't you are engraving the vector image. That can be checked with open lid. After everything set up, it is mandatory to turn on ventilation and exhaust, to get rid of the burnt material.
This is the image of cutter at work and cut pieces.
