Edinburgh Hacklab

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 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

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)

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

• boxes.py is a nice site for generating different types of finger joint boxes

Engraving Gray scale images

• Method 1 - dithering
• LaserCut 5.3 accepts monochrome bitmaps in “File” → “Open”
• Simmilar process to 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
• 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, then cleaned up with a wet cloth: https://youtu.be/Vl41zsCRWI4
• 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

• https://www.youtube.com/watch?v=rWMgsjQtyd4
• Cut and engrave your object and a mirror image of it at the same time
• Switch the 2 copies around
• run the engrave again

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

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

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

• 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.
• Fusion 360 has a plugin which does kerf correction automatically: 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:
• Piccolo assembly – “Draft angle on the laser-cut edges”
• Lasercut pneumatics – Fig. 4

• https://hobarts.com/ - The hacklab gets all its materials there
• https://www.sheetplastics.co.uk/
• Ebay