Edinburgh Hacklab

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Page for useful/cool things to do with the laser cutter for new and experienced users

===== Resources / Project Ideas =====
  * [[https://www.thingiverse.com/tag:lasercut|Designs for laser cutting on Thingiverse]]
  * [[https://www.reddit.com/r/lasercutting/top/?t=all|/r/LaserCutting on Reddit]]
  * [[https://www.makercase.com/#/ | Makercase]], for creating boxes, including with organiser dividers

===== Material tips =====


**Acrylic**
  * Engraving works best with the protective film off, but for cutting its good to keep it on as it keeps the surface clean
  * IPA can be used to clean up engraved and cut acrylic
**Wood**
  * All woods can be engraved, but not all cut cleanly, and some glues release nasty fumes. Lasersafe ply is guaranteed to cut well.
  * Masking tape put on the surface of the wood will stop burn marks
  * The density of plywood, unlike MDF and acrylic, is not uniform (it’s a natural material), so for a reliable cut, the speed should be set lower than is required for cutting through normally, as it needs to cut through the denser areas as well

**Metal**
  * Bare metal does not do anything under the laser, except reflect it back
  * The laser will however etch off paint and dye from metal. Anodised aluminium works great: [[engravingaluminium|]]
  * To etch bare metal, it can be coated with a heat activated chemical (Molybdenum Disulphide). Sold as “Dry Moly Lube” : https://www.youtube.com/watch?v=5ziyB9EEnL8
  * Settings: 25 speed, 100 power, 0.5mm scan gap works fine (Costa)
  * Thin metal can buckle from the heat - turning off Bi-dir and lowering power helps with this
  * Costa has experience with this

**Rubber**
  * Normal silicone rubber is safe to cut and engrave on the laser, can be used to make custom stamps
  * Silicone rubber leaves behind a lot of white powder, which can be cleaned up with IPA and lots of scrubbing
  * Other types of rubber may be safe to cut, but research and make sure they absolutely do not contain chlorine
  * Laser safe rubber is also available online: https://hobarts.com/rubber
**Vinyl**
  * Normal vinyl is not laser safe (Polyvinyl chloride, as the name suggests releases chlorine)
  * Laser safe vinyl is available online

**Paper/Card**
  * The air pump can be turned off when cutting paper to stop pieces getting blown everywhere. Remember to turn it back on when you're done
  * Layout paper (very wide masking tape) can be used to pick up all the pieces of your finished cut while keeping them together
  * The smaller laser cutter may be better at cutting paper as it can cut slower than the large one

**2 colour Laminate**
  * The edges of the thin [[https://hobarts.com/1.5mm-black-on-white-laminate-610x305mm-ref-2901-|1.5mm laminate]] can get burnt when cutting is done in one pass
  * It might give a better result if cutting with multiple passes at lower power

**Glass**
  *Glass can't be cut on the laser, but it can be "engraved", in that the surface of the glass chips when under the heat of the laser, leaving a frosted surface (careful, as tiny bits of glass can break loose).
  *Engraving: https://www.epiloglaser.com/how-it-works/applications/glass-etching.htm
  *Engraving lines can be used to score glass for cutting https://www.epiloglaser.com/customer-spotlights/laser-laceworks/

**Food**

Food that lasers (not an exhaustive list):
  * Pancakes
  * Biscuits
  * Bread
  * ham
  * nori
  * tortillas
  * Fruit/Veg - https://www.youtube.com/watch?v=a0PWI3sfQ0U
  * egg shells - https://www.youtube.com/watch?v=-W0vg6wzy7k
  * ginger bread - https://www.instructables.com/id/Laser-Cut-Gingerbread-House/
  * Most of these taste terrible as the laser burns them
  * The laser cutter is very dirty, use a sheet of paper, cos the laser can chip enamel off normal plates (I think)

**Misc**
  * Human Skin (not a good idea) https://www.youtube.com/watch?v=4-BfsnTw1X4

**PLA**
  * It can be cut but smells really bad so we don't recommend long cuts
  * Material has a tendency to warp when heated up
  * Longer and slower cuts can easily melt the material
  * If cutting 3D printed material the laser may seal the infill inside (as if it was cauterizing) 

===== Techniques =====

**Making 3D shapes by stacking 2D layers**
  * https://apps.autodesk.com/FUSION/en/Detail/Index?id=8699194120463301363
  * https://www.youtube.com/watch?v=pr1YRP6rWdc

**Box generators**
  *[[https://www.festi.info/boxes.py/|boxes.py]] is a nice site for generating different types of finger joint boxes
  *[[https://www.templatemaker.nl/en/]] is a generator interesting shaped boxes and 3D shapes, targeting paper/card but useful to play with

**Engraving Gray scale images**
  * Method 1 - dithering
  * LaserCut 5.3 accepts monochrome bitmaps in "File" -> "Open"
  * Simmilar process to [[https://blog.aaronbot3000.com/2013/05/a-guide-to-better-dithering-on-laser.html|this]], but our laser software cant import multiple colours: 
  * Steps:
  * Dither an image in Gimp or this online tool https://29a.ch/ditherlicious/
  * use Gimp or ms paint to convert the image to a monochrome bitmap, alternatively imagemagick using: **magick.exe in.png -monochrome -alpha off out.png** (Windows) or **convert in.png -monochrome -alpha off out.png** (Linux)
  * open the image in LaserCut and scale it so one pixel corresponds to one line of the laser engrave (the height of the image in mm should equal the height of the image in pixels multiplied by the scan gap)
  * You can preview the output by clicking on "Laser" -> "Simulate"


  * Method 2 - vectorising
  * http://goinkscape.com/how-to-vectorize-in-inkscape/
  * An image is divided up into multiple layers, one for each brightness level, in inkscape
  * Each layer is set to a different power setting in LaserCut

**Painting**
  * Paint can be rubbed into etched areas in acrylic (with sponge or cloth), then cleaned up with a wet cloth
  * Same can be done for wood: https://youtu.be/9WNd82-K09E
  * Multiple colours can be done with repeated spray painting and engraving the reverse side of clear acrylic https://youtu.be/SxNQgyL0dXY

**Double sided engraving**
  * Cut and engrave your object and a mirror image of it next to it at the same time
  * Switch the 2 copies around
  * run the engrave again

**Rotary Axis**
  *The Big laser has a rotary attachment for engraving and cutting cylindrical objects
  *To use it:
  *lower the bed of the laser down until you can see 2 switches and a socket on the right wall of the cutting area
  *bring the laser head to roughly the centre of the bed
  *plug in the rotary axis and flick both switches, this changes the laser from controlling the up/down motor to controlling the rotary axis motor
  *cutting and engraving is done exactly the same as before, you may need to adjust the vertical scaling to get a nice result
  *when you're done, don't forget to return the laser to the state you found it in

**Making rigid material flexible with living hinges**
  * virtually any rigid material can be made flexible (plywood and acrylic work fine)
  * https://www.instructables.com/id/Curved-laser-bent-wood/

**Cutting thick material**
  * The laser cutter has a limit to how thick it can cut, but this can be cheated with this technique:
  * Do one pass with the laser focused to the surface of the material
  * Then, focus the laser lower down and run the cut again
  * This will require some trial and error
  * Costa has experience with this

  * Another method is to engrave from [[https://www.youtube.com/watch?v=DQXuzTTf2QE|both sides of the material]], using a jig to make sure the two cuts are aligned

**Hatching**
  * In engrave settings, the scan gap can be set really high (eg 1mm or more) to create a hatching effect
  * This combined with an outline looks quite cool
  * TODO: insert image

**Acrylic bending**
  * Can be done with hair straightener or hot air gun
  * Costa has made a nice jig for bending acrylic at precise angles, consisting of nichrome wire, 2 board boards and a hinge https://www.instructables.com/id/Acrylic-Bending-Tool/
  * This can also be done on the laser, using an out of focus beam or with the lens removed https://a-e-mag.com/features/try-bending-acrylic-laser
  * Another cool example of this: https://www.youtube.com/watch?v=arjRtCjI9AQ
===== Design =====
**Removing duplicate lines**
  * Lines cut double in your designs will burn your material
  * luckily Adobe Illustrator can solve this https://www.youtube.com/watch?v=hcIKxlJTPxM
  * haven't found any alternatives so far

**Kerf correction**

Example of this in action (slope may be different for different materials and settings) in figure below:
{{https://www.researchgate.net/profile/Jetro_Pocorni/publication/287815638/figure/fig4/AS:309555671126016@1450815231017/Kerf-width-data-for-aluminum-plate-cut-with-a-6-kW-CO-2-Laser-over-a-range.png}}
  * Pattern for testing out different tolerances for tight fitting finger joints: [[https://www.festi.info/boxes.py/BurnTest?language=en]]
  * Good explanation: http://archive.fabacademy.org/2018/labs/fablabsiena/students/giuseppe-allocca/laser%20cutting.html
  * The laser cutter has something called “kerf”, if you send a 1cm square to the laser, the part will come out slightly smaller (~9.8mm)
  * This difference is about 0.1mm, so paths need to be offset by 0.1mm to compensate for this using the offset tool in Lasercut 5.3
  * Fusion 360 has a plugin which does kerf correction automatically: [[https://apps.autodesk.com/FUSION/en/Detail/Index?id=7634902334100976871&os=Win64&appLang=en|link]]
  * This should also be possible with the “offset path” tool in any vector editing software like Inkscape or AI

**Trapezoid Cross section**
  * The top of the material spends more time in the laser beam than the bottom, this causes a draft angle on the edges
  * How pronounced the angle is depends on the thickness and type of material being cut
  * This is usually not an issue, but if it is, like if you want it stand up straight on its edge, you can sand it flat
  * Another option for designs with multiple laser cut parts, the direction of the draft angle can be flipped for mating edges
  * Examples of this in action:
  * [[https://github.com/DiatomStudio/Piccolo/wiki/Piccolo-Assembly-Instructions|Piccolo assembly]]  – “Draft angle on the laser-cut edges”
  * [[https://www.researchgate.net/publication/286652510_Laser-cutting_Pneumatics/figures|Lasercut pneumatics]] – Fig. 4

**General Laser cutter inaccuracies**
  * https://youtu.be/sEUol9R1OhQ

===== Material sourcing =====
  * https://hobarts.com/ - The hacklab gets all its materials there
  * https://www.sheetplastics.co.uk/
  * Ebay