Introduction: Trying My Hand At: Laser Cutting and Etching [Pittsburgh Tech Shop]

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Today at the Pittsburgh Tech Shop, I took a class in laser cutting and etching. A laser cutter is a machine that uses a focused laser to burn or melt away an image onto a sheet of raw material. Laser cutters can be used to etch or cut a variety of different materials from certain kinds of plastics to leather. It takes a vector file as input and in a few minutes will reproduce it on your chosen material. 

In this tutorial, I will be using a Trotec laser cutter and Corel Draw to etch a vector image I made onto a small sheet of acrylic.

I will briefly discuss the material and vector that I chose before I go into more depth about the printer and printing software itself. Note that this is an overview for this particular kind of laser cutter; there are many kinds of laser cutters and software available. This should give you a general idea of what the process is like. Chances are if there's a laser cutter available to you you'll have to do a bit of research before you can use it.

WARNING: this is a basic intro to laser cutting as a concept. Laser cutters can be damaged and can be dangerous if not used correctly. It is highly recommended that you receive formalized training before using one.

More information about the Pittsburgh TechShop can be found at http://techshop.ws/

I made it at TechShop!

Step 1: Choose Your Image

As there are plenty of variations to laser cutting, I will focus on one particular kind in this Instructable. As previously mentioned, I will be using a Trotec laser cutter, Corel Draw, Job Control, and a sheet of acrylic as my material.

Time: from 15 minutes to 3 hours
[Note: time varies greatly based on factors such as familiarity with the machine, raw material, complexity of input file, and experimentation with laser settings]
Tools:
-Laser cutter (Trotec for this tutorial)
-Vector software (e.g. Corel Draw, Adobe Illustrator)
-Laser cutter driver software (Job Control)
Materials:
-Vector file of your design
-Sheet of raw material (acrylic)
[As a rule of thumb, you should bring more material than you plan to use in your final product. It is common to get the settings or placement wrong when working with an unfamiliar material]

After assembling your materials, the first thing you should do is decide what you'd like to etch. Trotec laser cutters can take both raster and vector data.

Raster images are composed of a series of pixels. If you choose a raster formatted image, like a .png, .jpg, or .gif, the laser will make deeper marks on darker pixels and lighter marks on lighter pixels.

Vector images are composed of equations of lines, curves, and other relavent data. You can make them with programs such as Adobe Illustrator or Corel Draw. If you choose a vector image, the laser will follow the lines described by your inputed file. The strength of the laser will depend on how dark your lines are on a white to black scale.

For this Instructable, I took inspiration from a character my friend made for a game and I made a quick vector design in Illustrator for the character's Business Crab Enterprises.

Step 2: Materials to Choose From

At the Tech Shop, they have a list of materials that have been approved for the laser cutter. They also have a ring of example materials that the laser cutter will accept. 

Always check to make sure that that you want to cut can be processed by the laser cutter; there are some materials that just won't cut, but others will melt, produce gas that can ruin the laser's lens, or produce toxic gas if cut. Below are the materials approved for the Trotec. Again, not all laser cutters are the same. Please check that your material is okay for your particular cutter before cutting anything.

Here are some materials that CANNOT be cut by a laser cutter and why:
  • Vinyl, PVC, Foam Core, Polymer Clay: produces Hydrogen Chloride gas
  • ABS: produces Hydrogen Cyanide gas
  • Styrofoam: can start a fire
  • Metal, mirror: can reflect laser back into internals of machine
  • Polycarbonate, PETG: Does not cut
  • Fiberglass: this one varies; check with the machine manufacturers or owners

Step 3: Choose Your Material

I chose a sheet of scrap acrylic for this piece. It can be both cut and etched by a laser cutter. 

Please note that if you are unfamiliar with laser cutting, have not worked with your chosen material before, or are using a particularly expensive or difficult to acquire material you should test your laser settings on a scrap piece of that material before you start your final project. It is very easy to choose the wrong settings and ruin a piece of raw material.

Step 4: Laser Cutter: Basic Information

The laser cutter is a large machine with a few important parts to be aware of. This is just a brief overview of the machine; we will go through all of the steps to operate the laser cutter that has already been set up.

Top lid: You open the door on top of the laser cutter to place your piece. You can look through the lid to watch the progress of the cut. 

Power switch: On the Trotec, the power switch is on the back of the machine. Make sure it is turned on before attempting to use the machine.

Control panel: This is where you set the laser position, receive error warnings, and pause the cut. We will go into this in more detail soon.

Ventilation: The cutting process produces gas, particulate, and usually a small amount of fire from the heat of the laser. The ventilation system is there to sweep away any gas produced and to keep the fire low. (Note: the fire produced by the laser should always be less than a centimeter in size. If your piece catches fire, stop the job IMMEDIATELY by lifting the lid)

Head: This contains the lens that focuses and reflects the laser onto your surface. It moves in a two dimensional plane according to the file you give the printer to cut the image into your material.

Support grid: This is the platform onto which you place your material. This honeycomb aluminum grid will hold up your material while allowing for proper ventilation.

Side Rulers: The bed of the laser cutter has rulers along the edges. You will be using these to compare the dimensions of your piece with your input file.

Front door: This door allows you to access the area under the support grid. It should be kept clean and should never be used as a storage space.

Step 5: The Laser Cutter Control Panel

The control panel has a few buttons; in this tutorial, we will be using the arrows. The red arrows control the position of the laser head--when the laser cutter is not running, you can use them to manually position the head. You can press on them for as long as you like and they will not damage the laser head; they'll stop before they reach the edges. You should still be careful that when you begin cutting that the head is not positioned over the rulers on the edges of the machine.

The black arrows are for moving the support bed up and down. Be careful when using these buttons--moving the bed too far up can make it collide with the laser head and can damage the machine.


Step 6: Placing Your Piece

Place your material on the grid in the upper left corner. Make sure the edges of the material are flush against the rulers. If your piece is irregularly shaped like the one in the picture below, make sure that it is as close as possible.

If the laser head is too close to the bed for you to slide your piece underneath, use the up/down arrows to move the tray down first.

Step 7: Adjusting the Laser's Focus (Part 1)

The laser cutter has an autofocus mechanism. The focusing mechanism shines out of a small port near the upper left hand corner and measures how tall your material is when laid flat. If your material is thinner that the rulers on the edges of the support bed, however, it will focus on the height of the rulers rather than on your material. If this is the case, you will have to manually focus the laser.

The laser cutter should come with a small metal tool (pictured below). It two feet on the bottom and a small square on the back. Identify this piece or ask for the equivalent for the laser cutter that you are using.

Step 8: Adjusting the Laser's Focus (Part 2)

There is a ridge on the side of the laser head. With the feet of the focusing tool pointed down, carefully balance the metal square on that ledge. Make sure the laser is far enough from the support bed that the feet of the focusing tool are not touching the material. Also be sure that the laser is positioned above your material, not the rulers. Use the control pad to move the laser head if necessary.

Step 9: Adjusting the Laser's Focus (Part 3)

Now that your focusing tool is in position, carefully raise the support bed in small increments. Hold the button down for larger increments and tap for smaller increments. When the feet of the focusing tool start to get very close to the material, make your increments as small as possible. Stop when the measuring tool is nudged gently by the material or falls off of the laser. The laser head is now in the focused position.

Step 10: Close the Lid

Now that your material and laser head are in position, close the top lid. The laser cutter will not operate unless the lid is closed.

Step 11: Connecting to the Laser Cutter

Now that you've prepared the laser cutter itself, it is time to switch our focus to the software. 

At the Tech Shop, there is a dedicated computer wired to each laser cutter. It has all of the proper software to operate the laser cutter installed: Corel Draw, Adobe Illustrator, and Job Control. I will not be going into detail as to how to set up a station like this; if you are in a position where you need to install software or connect to the cutter for the first time, I would advise you to do some research or ask someone who is qualified on the subject.

Step 12: Software Setup: Using Corel Draw (Or Adobe Illustrator)

A few important notes about your file: your color mode should be RGB, not CYMK. The Trotec laser cutter uses RGB colors to determine which lines to cut and which to etch; CYMK colors will not work. If you are creating a new file in Corel Draw, be sure that the color mode drop down menu points to "RGB".

Open Corel Draw. If your file was made in Corel Draw, open it. If it was made in Illustrator, first create a new RGB file and import it. Both options can be found under the "File" menu.

Step 13: Software Setup: Lining Up Your Piece

Use the rulers on the edges of the window to line up your piece. It should be completely within the canvas area; anything outside of the canvas area might not print.

You should also use the rulers to determine the size of your piece; the selection arrow in the upper left hand corner can be used to both move and resize your design. [If you are unfamiliar with CorelDraw software, I would recommend viewing a basic tutorial]

Step 14: Software Setup: Line Weight and Colors

The Trotec printer is configured to etch anything in black or grey and to cut anything in RGB red. It will only cut lines that are set to "hairline" weight. 

To change the color and weight of your lines, begin by selecting a line that you would like to change. In my example, I want the outer rectangle to be cut out of the material but I want the rest of the design to be etched. I therefore select the outer rectangle.

In the lower right hand corner of the window there should be a set of buttons (highlighted in the picture below). If you click on the lower of the two boxes, a menu like the one shown below should pop up. Click on the color box and select "RGB Red". Click on the width dropdown and select "hairline". Click the "Ok" button when you are done. Repeat this for any item you wish to cut out or change the width of.

Step 15: Software Setup: Sending Your File to Job Control (Part 1)

When you are ready to cut out your piece, go to the File->Print menu option. In the printer dropdown, select "Trotec Engraver". Next click the "Preferences" button next to the Printer selection dropdown.

Step 16: Software Setup: Sending Your File to Job Control (Part 2)

The Preferences menu will let us view the settings that are specific to the laser cutter. 

In the "Size Settings" section of the menu, specify the width and height of your material. 

In the "Material Settings" section, select the material type and subtype from the dropdown. I chose "Plastic" and "Acrylic".

When you are finished, click on the button marked "JC". This will send the file, placement, and materials preferences to the laser cutter program called Job Control. Close out of this menu, press "Apply" and "Print" in the Print Menu, and switch over to the Job Control program. (If Job Control isn't open, open it manually.)

Step 17: Job Control: Placing Your Image

In Job Control, your image should show up as a grey rectangle on the screen. (If you would like to see your entire image, click on the eye icon highlighted below). If you do not see your job in the middle of the screen, select it from the Job menu to the right of the main window. If you still do not see it, try going back to Corel Draw and reapplying your preferences in the print menu.


Step 18: Job Control: Printing Your Image

Using the four arrow keys on the control panel indicated earlier, move the laser head into position. You should see its position indicated by the crosshairs in Job Control. They should update their position as you move the laser head with the arrow keys. When you have the head in place, click and drag the rectangle to position it near the center of the crosshairs. It should snap to the center when you release the click.

The rulers in this window correspond with the rulers on the edges of the laser cutting bed. In order to save space and to not waste material, use these rulers as guides to get your material and file lined up. My material is an irregular shape; I therefore positioned my file so that it wouldn't run off the edge of the material.

When you are ready to print, click the "Play" button in the lower right hand corner.

Step 19: The Cutting Process: Waiting, Watching, and Material Removal

The laser cutter will now begin to trace your pattern on the raw material. While the laser is on, DO NOT LEAVE THE MACHINE UNATTENDED. It is not uncommon for the material to catch fire or for the material to behave in a way that you don't want it to. Remember, if something goes wrong, lift the top lid immediately to stop the cutting process. Be aware that after you do this, you cannot resume your cut and must start from scratch.

Keep an eye on the cutting process. That being said, do not look straight at the laser beam. It can damage your vision.

The cutting process can take anywhere from less than a minute to an hour or more. Often, you will need to do more than one pass on the laser cutter for the cut to go all the way through the material. If the design is intricate or the material demands a slower cut, be sure to allocate enough time for the cut to finish. Again, it is highly recommended that you test the laser settings on a piece of scrap material before you start a bigger project.

The laser cutter should beep when it is done cutting. Lift the lid and pull out your material. Pop out any extra pieces cut out by the laser. You should also remove any remaining scrap material from the laser bed.

Step 20: Tada!

Here's the finished piece! It looks a bit like a futuristic business card. 

You may not have gotten the effect you wanted--it is common in laser cutting to not turn out the way you expected the first time. If lines are skipped in the cutting sequence or parts of your piece do not turn out quite right, adjust your settings in Corel Draw, Print Settings, or Job Control. It may take a few tries to get it right.