Presentation

# Laser Cutting

???
What does LASER mean ?
See answer next slide.

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# Laser

<br>

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Light Amplification by Stimulated Emission of Radiation
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<br>

???
Laser is a powerful, directional light.

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## Principles

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A concentration of energy that will burn the matter.
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- Perpendicular to the surface (2D)

- Enables the cutting or engraving of thin materials

- Laser beam = work is carried out at the focal point 
<br>
(focus point)
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???

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# Safety

???
Make them think of the 3 main security points they need to have in mind :

1. Fire
2. Smoke
3. Laser
+1. the FabManager

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## Fire risk

<br>

- I **keep an eye on the materials** whilst they are being cut

- I know where the **fire extinguishers** and **fire blankets** are

- I know where the **emergency stop button** is

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## Toxic fumes

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- I always **switch on the extractor** fan / filter

- I **keep an eye on the smoke** whilst cutting
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## Laser

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- I put on the special **safety goggles**

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## Materials

#### Permitted materials

- Acrylic (PMMA/Plexiglas)
- Untreated wood
- Plywood (multiplex)
- Textiles
- Paper, cardboard

⚠ **Warning!** Corrugated cardboard with 3 layers (or more) can **catch fire** easily! ⚠

<br><br>
Thickness: 4 mm maximum

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## Materials

#### In small quantities

- MDF 
- ABS, Polystyrene (PS)
- PE, PET
- Polypropylene (PP)
- Polycarbonate (PC), Nylon (PA), Polyurethane (PU)
- Fibre-reinforced composites

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#### Reasons

- clogs filters quickly
- not optimal to be laser cut

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Thickness: 4 mm maximum

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## Materials

#### Prohibited

- Other MDF
- PVC
- Copper
- Teflon (PTFE)
- Phenolic resin, epoxy
- Vinyl, imitation leather
- Animal leather

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#### Reasons

- High toxicity 
- Cannot be laser cut with normal lasers

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# Wavelength

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Different laser types uses different Wavelength
FabLab ULB only has CO2 Laser

UV good for glass work
Fiber good for metal
Pointer laser in visible spectrum

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# Working steps

#### 1. 2D Modelling

- Vector drawing
- Colors

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#### Programmes

- Inkscape
- Illustrator
- FreeCAD (2D export)
- AutoCAD
- ...

#### Method

- Export/Save as .SVG
- No white space
- Be careful with the scale!

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???
Step 1 - design
We can use different apps (3D -> export faces)

SVG is safest option as more universal.

If designing in 1:1 scale (usually architects) -> export so it can fit inside the laser cutter.

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# Working steps

#### 1. 2D Modelling

- Vector drawing
- Colors

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#### Color is used to define:

- speed and power settings
- a specific command
- the order we want to cut the design

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???

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## Working steps

#### 2. Materials

- Size of the material
- Thickness
- Safety

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#### Influence

- laser cutters have a given working area
- the design, particularly where objects fit together
- the robustness of the design
- strength

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## Working steps

#### 3. Choose your parameters

- Mode (engraving / cutting)
- Speed/Power

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## Operating modes

| Cutting | Vector engraving | Surface engraving |
| --- | --- | --- |
| Burns through the entire thickness of the material    | Burns only the surface | Burns only the surface |
| Line = vector | Line = vector | Solid surface |
|  |  |  |
|  |  |  |
| ![img](./img/laser-general/demo-cut.jpg) |![img](./img/laser-general/demo-eng-vect.jpg) |![img](./img/laser-general/demo-eng-fill.jpg) |

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## Speed / Power Parameters

The variables we can play with are the Speed and the Power

???
Given as examples.

They are **specific to the laser cutter**.

Power usually given in %.

50% of a 60W laser is not the same as 50% of a 150W laser.

Always test some of the parameters before cutting.

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##  Speed / Power Parameters

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#### How to choose

- Sharpest image
- Least burnt
- Fastest

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<br><br><br>
Note: 
<br>
In some laser cutters the pressure of the compressed air can be regulated.
This can influence the cutting process.

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???
Always test some of the parameters before cutting.

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## Working steps

#### 4. Cutting

- Manual focus
- Autofocus

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<img src="./img/laser-general/focus-chart.jpg" alt="Import" style="height:350px" />
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???
Out of focus gives us:
- dispersed laser 
- less power to cut
- bigger lines

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# 2D and 3D

We cut out 2D shapes, but this does not prevent us from making 3D objects

However, it usually requires assembly using interlocking joints

Useful site for generating [box](https://boxes.hackerspace-bamberg.de/) designs.

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# Kerf

##### Burning = loss of matter

- Depends on the thickness
- The material (fire resistance)
- Speed-power ratio

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- Number of cycles
- Depends on the focus

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Laser cuts in center of the line so it cuts away on both side.

This introduces an "error" not present in the design.

Kerf is laser cutter specific.

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## Kerf tests

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You can measure the error by doing a Kerf Test

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## Kerf tests

The laser beam has a certain thickness, which must be taken into account when joining parts together

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Brush test.
Make a brush with intended error and check the fitting.

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# Useful Site & Apps

- Boxes.py

- Deepnest.io

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## [Boxes.PY](https://www.festi.info/boxes.py/)

Create boxes (and other designs) quickly.

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???
Generate boxes (and other stuff) automatically.

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## [Deepnest.IO](https://deepnest.io/)

<br>
Optimizes cutting path resulting in quicker cutting.
<br>

???
Optimise tool path.
2 lines can become 1 to save time.

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# Maker Rule

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# FabLab's Specific Laser Cutters

<br><br><br><br>
For the Laser Cutters specific to our FabLab see the following [Slides](https://fablab.ulb.be/slides/laser-our.html)
<br><br><br><br>
For issues and improvements you can contact us at fablab@ulb.be