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LaserLab 101

How It Works

  • Laser tube in the back

  • 120W Carbon Dioxide Laser

  • Fires out the left side, 1 cm thick beam

  • Bounces off mirrors

  • Hits lens, focuses to 0.01 mm beam

  • Focus height - explain principal teach during setup

  • Laser turns off if lid is lifted, but laser head will keep moving


Materials

  • Wood

    • Up to 3/8“

    • Can cut 3/4“, but very slowly

    • Baltic birch plywood is highly recommended over other plywoods

  • Acrylic

    • Up to 3/8“

  • Fabrics

  • Metal

    • Etch, using special spray

  • Ceramics, Glass

    • Etching

  • NO VINYL or PVC, ever. A credit card is PVC. A vinyl record is vinyl. Super bad for you and the machine

Different Laser Cuts

  • Cut

    • Laser cuts through the material following a vector line

  • Trace

    • Laser traces, leaving a mark on the material along a vector line

  • Raster

    • Laser engraves an image into the material in a black/ white (engrave/raw) method

  • Raster with Dither

    • Laser engraves an image into the material in a grey scale (engrave/partially engrave/raw) method

  • Raster with higher dpi

    • Laser engraves an image into the material with a higher precision.

Different Laser Techniques

  • Jigging

    • To engrave or cut into something perfectly, the way you set your zeros

  • Different Bases

    • The honeycomb is great for small pieces. It can heat up from the laser and scorch the bottom of your piece.

    • The metal grate (underneath the honeycomb) has fewer bars, and scorchs your piece less.

    • A wooden base, underneath your piece, will reduce scorching

  • Taping your piece (masking tape)

    • Taping your piece will remove scorching wherever you cut

    • Downside: you will have to remove it afterwards and depending on your cut, could be very tedious

  • Vector Current

    • Vector current is always set at 100%, and is a multiplier added to vector cuts. If you need to reduce the laser power lower than 1, adjust this multiplier.

  • Cutting out of focus

    • With the laser in focus, the line beam is 0.01 mm wide and will leave a trace the thinnest possible, depending on how the material reacts

    • Taking the laser out of focus, the width of the beam will be larger if you want a thicker trace

Safety Considerations

  • Power button

  • Before cutting make sure the fan is on

  • NEVER LEAVE THE LASER CUTTER when it is on.

  • Clean up! Users are responsible for clean up after themselves

  • Water spray

  • Fire extinguisher

  • If you're ever unsure of anything, ask staff


NEVER CUT THESE MATERIALS

WARNING: Because many plastics are dangerous to cut, it is important to know what kind you are planning to use. Make has a How-To for identifying unknown plastics with a simple process..


Material

DANGER!

Cause/Consequence

PVC (Poly Vinyl Chloride)/vinyl/pleather/artificial leather

Emits pure chlorine gas when cut!

Don't ever cut this material as it will ruin the optics, cause the metal of the machine to corrode, and ruin the motion control system.

Thick ( >1mm ) Polycarbonate/Lexan

Cut very poorly, discolor, catch fire

Polycarbonate is often found as flat, sheet material. The window of the laser cutter is made of Polycarbonate because polycarbonate strongly absorbs infrared radiation! This is the frequency of light the laser cutter uses to cut materials, so it is very ineffective at cutting polycarbonate. Polycarbonate is a poor choice for laser cutting.

ABS

Emits cyanide gas and tends to melt

ABS does not cut well in a laser cutter. It tends to melt rather than vaporize, and has a higher chance of catching on fire and leaving behind melted gooey deposits on the vector cutting grid. It also does not engrave well (again, tends to melt).

HDPE/milk bottle plastic

Catches fire and melts

It melts. It gets gooey. Don't use it.

Polystyrene Foam

Catches fire

It catches fire, it melts, and only thin pieces cut. This is the #1 material that causes laser fires!!!

Polypropylene Foam

Catches fire

Like PolyStyrene, it melts, catches fire, and the melted drops continue to burn and turn into rock-hard drips and pebbles.

Fiberglass

Emits fumes

It's a mix of two materials that can’t be cut. Glass (etch, no cut) and epoxy resin (fumes)

Coated Carbon Fiber

Emits noxious fumes

A mix of two materials. Thin carbon fiber mat can be cut, with some fraying - but not when coated.


How It Breaks

  • Running the floor up into the laser head (super bad)

  • Running the laser head into the edges (less bad), need to re-home after that occurs

  • If you ever hear a loud noise, unwanted laser/bed movement - HIT THE POWER BUTTON

Support Systems

  • Exhaust switch by large laser cutter must be ON, every other support system turns on automatically with fob - must be on before a job starts - exhaust -- pulls out smoke and fumes - cooling -- laser tube gets hot, doesn't like to be hot - air compressor -- keeps lens clear -- blows out small fires -- stokes embers


Machine Set Up

  • Lay and secure material on the bed, move laser head away, and how to align (z -direction, and horizontal zero)


Software

1) Design from InkScape

  • If using any other softwares at home, save them as vector PDF’s

  • All objects must be ungrouped

  • Cannot use clipping paths or masks

  • Image gets rastered into the the raster tab - explain about B/W Threshold

  • Vectors get vectored from the vector tab


2) RetinaEngrave 3D

  • Must be running

  • Check for connection in the bottom left

  • Home it if not homed

  • Home is in the upper right because that's where the proximity switches are

  • Arrow keys control laser head, page up/down controls floor

  • Focus depth tool explained

  • Jog perimeter

  • Estimate time

  • Explain pause and stop

  • Raster then trace then cut. Explain tabs, vector order and passes.


3) Rastering Tab

  • Like a printer, moves back and forth and fills in area

  • Raster is by default ignored in RetinaEngrave 3D

  • You can control: speed, power, b/w threshold, DPI

  • Black/White threshold is the level that divides black, what gets engraved, and white, what does not

  • It takes approximately 1 minute per square inch


4) Vectoring Tab

  • Traces lines

  • Different line colors can have different settings

  • Order, speed, power, num passes! Never use more than 60% power and less than 20% speed without permission from Maker Labs staff


Settings on unfamiliar material

  • Run test cuts, start your guesses settings based on the closest material

  • Use “LaserLab 101 - Laser Test Cut.svg” and assign each colour a different setting


Create Keychains

  • Have each participant create a keychain using “LaserLab 101 - Keychain.svg” as a starting point

  • Demonstrate the technique of jigging, by flipping the key chain and rastering the back side


Cost

  • $1 / minute: Members ( the first 60 minutes of CNC time each month is free )

  • $1.50/ minute: Drop-in Makers

  • 2 / minute: full service fabrication



Resources

Laser Cutter Settings - these are subject to change and should only be a guideline
Make test cuts before-hand!

Don’t run over 60% power or under 20% speed!


Cut Settings

Material

Vector Cut Settings

Baltic birch plywood (⅛”)

Speed: 60           Power: 40 Passes: 1

Baltic birch plywood (¼”)

Speed: 60           Power: 40 Passes: 2

Bamboo plywood

Power: 60

Speed: 40

MDF (¼”)

Power: 40

Speed: 60

MDF (⅛”)

Power: 80

Speed: 40

Acrylic (⅛”)

Speed: 60           Power: 60 Passes: 1

Acrylic (¼”)

Speed: 40           Power: 60 Passes: 2

2.5 mm corrugated cardboard

Power: 30

Speed: 100

1 mm polystyrene

Power: 30

Speed: 100


Trace/ Raster Settings

Trace Test cut:     Speed: 100        Power: 1

Raster Test cut:     Speed: 100        Power: 10

  • To increase depth of cut, increase power

  • To decrease depth of cut, decrease power


FAQ

My image from Inkscape isn’t showing up in RetinaEngrave 3D

  1. Ensure in Inkscape:
       - Everything is ungrouped
       - There are no clipping paths or masks

  2. Check, in RetinaEngrave 3D, you haven’t selected “ignore raster” or “ignore vector”

  3. Copy your object from Inkscape into a brand new Inkscape file

The laser isn’t connecting to RetinaEngrave 3D

  • Try in this order:

  1. Unplug the laser, by usb, from the computer, then plug it back in

  2. Shut off the laser, using the red button, and turn it on again (wait 1 min)

  3. Restart RetinaEngrave 3D

  4. Restart the computer and the laser cutter simultaneously

Fill versus Stroke in Inkscape

The fill of an object is the space on the inside.
To change the fill, click a colour.


The stroke is the outside line.
To change the stroke, hold “shift” and click a colour.
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