Cheat Sheet

Laser Cutting

• RGB Document Color Mode

• Lines you want to CUT:

• Artboard 24” x 18” or less

Stroke Width .001” (.072pt)

File Document Color Mode RGB Color> >

Stroke Color RGB Red

Want to engrave instead? Make lines Blue

Make sure you have

the STROKE selected

(the hollow box)

Don’t see the

color panel? Go to

Window > Color

*

*

*

DO A TEST CUT!!!Seriously. Do it.

What does a laser cutter do?

A laser cutter uses a laser to cut computer-designed parts in flat sheet materials. Provided with 2D vector files, laser cutters can cut, engrave, or etch many materials.

The laser cutters in Room 36 are 60W CO2 lasers that blast through the workpiece and send the vaporized particles through a filtration system. It is critical that the filtration units are ON whenever the laser cutters are in use. The filters share an outlet with the laser cutters, so if your laser cutter is on, your filter is on, too. Check with the TA to make sure!

Adobe Illustrator is used to generate the vector paths for the laser to follow, but Illustrator can import/convert common vector formats (e.g. DXF, EPS, PDF, SVG) from other applications.

As operator of the laser cutter, you will provide the machine with a set of instructions:

• Cutting paths (created in Illustrator) • Laser focus height (determined by the material thickness you measure and enter) • Cutting Power, Speed, and Pulses Per Inch (PPI) (determined either by selecting a

material from the PRL Materials Database, or entering directly in Manual Mode)

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Etch (“Raster”)

Engrave

Cut

Don’t touch this! TA only!

Cutting paths are generated based on the geometry from your Illustrator file. Once in the Universal Control Panel (UCP), you will select which material you are using and enter the thickness you’ve measured. Based on these entries, UCP will determine the focus height and calculate cutting power, speed, and PPI.

Considerations for Cutting

Cutting with a laser is NOT like cutting with scissors because material is lost in the cutting process. The vaporized particles leave behind a kerf (a gap) in your material. This kerf is not always predictable or consistent. It is a good idea to do a test cut and measure the material loss if dimensions are critical in your design.

Further, the cuts a laser makes are NOT perfectly vertical. The beam isn’t perfectly straight up and down - it is focused at a point on the surface of the material. As the laser beam goes through the material (particularly thicker pieces) the beam deteriorates and leaves tapered edges.

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Laser Path

Kerf Width

(Side View)

Ideal

Reality

Steps for using the Room 36 laser cutters

1. Create your file 2. Pick your material 3. Show up for your reservation 4. Do a test cut 5. Do your real cut 6. Clean up (& get a shop job!)

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1. Create your file

Students most commonly create geometry for laser cutting in SolidWorks or Illustrator. SolidWorks is an excellent choice if you want to create any sort of parameterized design. Illustrator is terrible at this - you cannot tie one dimension to another unless you create a group, and this is only useful in certain circumstances. If you need to do any sort of hole placement, tab design, reference geometry, or tangent curves (among many other features) then SolidWorks is your best bet. Otherwise, Illustrator can technically create anything that SolidWorks can, but if you ever need to edit any complex geometry or fit it to specific dimensions, it’s a bit of a pain.

SolidWorks If you are coming from a SolidWorks part file, you may be tempted by the option to save as .AI directly from your part file. DON’T DO THIS! If you open this in Illustrator, you’ll find it’s just a screenshot of your part (This isn’t what you want…). Instead, you’ll need to create a SolidWorks drawing of your part.

Create a SolidWorks drawing • Go to File > Make Drawing From Part.

! • Uncheck “Display Sheet Format” • Better yet, select “Custom Sheet Size”, Enter “24in” x “18in”, and click “OK”. • If your SolidWorks model is a 3D part,

- Drag your model view from the View Palette onto the drawing

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• If your SolidWorks model is just a 2D sketch, the View Palette will not appear. - Instead, Go to Insert > Drawing View > Model…

- ! - Double click the name of your part file - Make sure that “Use Sheet Scale” is selected - Select the appropriate orientation - Click anywhere inside the document to place your sketch - If it all looks good, click the green arrow to finish

• Go to Edit > Properties and make sure your sheet scale is 1:1 • Hide/Delete any center marks or other unneeded reference markings • Go to File > Save As… and save your drawing as a .DXF or directly as .AI

To open your DXF in Illustrator

! • Choose “Original Size” and make sure each unit corresponds to 1 inch • Verify that your sizing looks OK

From here, continue on using the following instructions for creating a file in Illustrator.

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Illustrator If you are creating a file directly in Illustrator, there are a number of tools at your disposal that are outlined in the Illustrator binder. Have a look at this if you are just starting out in Illustrator, and it will go over the most often used functions.

Create your geometry, then follow the steps below to prepare your file for laser cutting: • Ensure your document is the correct color mode by going to File > Document

Color Mode > RGB Color

• Ensure that your Artboard is 24” wide by 18” tall or smaller - Click the Artboard tool or press Shift + O - Make sure your dimensions are within bounds - To exit Artboard mode, select another tool from the tool panel or hit “V”

• Select any lines you wish to cut and make sure they are RGB red (R255,G0,B0) - If you can’t find the Color palette, go to Window > Color - If it’s not showing RGB pickers, click the little menu icon at the top right

corner of the Color palette and select “RGB”

• Give these lines a Stroke width of .001” (.072pt) • Repeat with RGB blue (R0,G0,B255) for any lines you wish to engrave

Any other marks will be raster etched (this includes any images you’ve included in your design).

When your file is complete, you’re ready to select your material and make a machine reservation on Webshop. Skip to Step 3 if you’ve already selected your material and verified that it can be cut at the PRL.

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Stroke Color

2. Select your material

The PRL laser cutters can cut, engrave, and etch a variety of materials, but they are limited in their range for various reasons, mostly due to health and safety. Many materials are inconsistently labeled/manufactured in the wild and as such can contain unpredictable blends of chemicals that are toxic and/or caustic when vaporized. We do not cut materials known as or suspected to be toxic/caustic when laser cut, and we always err on the side of safety. See the lab manager if you have questions about this.

Additionally, some materials require an extra feature known as gas assist, and the PRL cutters do not have this feature. This means that certain plastics, while they are fine and perfectly safe to cut elsewhere, cannot be cut in the PRL. See below for a full list of allowable materials.

Sometimes a material that you have laser cut safely on other machines elsewhere cannot be cut on the PRL laser cutters. We are sorry for the inconvenience and can direct you to other resources for cutting these materials outside the PRL.

The materials we can cut safely include: • Acrylic (mirrored, textured/frosted, opaque, transparent) • Duron • Some Hardwoods (Black Cherry, Pine, Poplar, Walnut, Ash, Maple, Basswood) • High-quality Birch plywood • Corrugated cardboard • Matboard • Chipboard • Silicone • Cork • Various papers/card stock • Foam core • PHBV (special material used by bioscience researchers) • Leather • Skid Tape • Felt • Cotton fabric • Ripstop nylon • Mylar film • Kapton

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The materials we can engrave/etch (but not cut) include: • Anodized Aluminum • Glass • Stone

The materials that are not allowed include: • Any hardwoods NOT explicitly listed above • Low quality/Home Depot plywoods • Polycarbonate • PTFE • PVC • Delrin • Carbon fiber • Fiberglass/circuit boards • Transparency sheets • Camera gels • Polypropylene (HDPE, LDPE, etc...) • Polyethylene • Styrene • Neoprene • Laser-engravable rubber stamp material • ANY material not explicitly allowed AND cleared with the Room 36 manager

For more detailed information about these materials, check the Materials Compendium at the back of the binder.

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3. Show up for your reservation!

Laser cutter reservations on WebShop fill up quickly, and you need to be at the lab on time to claim your reservation!

When you check in with the TA… • If you have a reservation, the TA will add your name to the laser waitlist

whiteboard or, if you are high enough on the list, give you access to a machine. • If you do not have a reservation, the TA will add your name to the laser waitlist

whiteboard AFTER the students with reservations

If you’re lucky enough to show up when there is no queue (pro tip: mornings are usually pretty slow!) then you may be able to use a machine right away.

The laser waitlist whiteboard dictates the order of priority and is usually enforced not only by the TA but by other students eagerly awaiting their turn. When you are done with the machine, find the TA and he or she will call the next name on the list.

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4. Do a test cut

Test cuts are critical both to ensure good cut quality and keep the machines running smoothly. Bad cuts can generate lots of little burnt particles that clog up the lenses, which further degenerates the cut quality. Bad cuts also waste your material and time, so head that off at the pass!

For your test cut, use the exact material you plan to use for your real cut. If you can’t spare any material, hopefully there will be some scrap on the wire rack. It really does need to be your exact material for this to be useful.

****Important note****

These machines, while pretty darn good at what they do, don’t always cut the same everywhere on the 24”x18” cutting table. When doing your test cut, put your material wherever on the cutting table you’ll be doing your actual cut.

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Good Cut

Particles get sucked away and into the filtration system

Bad Cut

Particles cloud the beam and fuse to the focusing lens (This ruins the lens and makes cuts worse)

Test Cut Here

Real Cut in Same Position

To do a test cut: • Find the test cut Illustrator file on the desktop and open it in Illustrator. • Go to File > Print (or Ctrl+P), make sure “Printer” is VLS4.60, and click Print.

• Nothing will happen! This is normal! • Find the red diamond icon in the lower right Windows tray and click it to open up

the laser cutter control panel.

• Verify that the test cut file has loaded properly - all your cut lines should be red. • Measure your material with calipers - it’s important to get an exact

measurement. Calipers live in the tan drawer in the desk under Cookie and Oscar’s computers.

• Enter your material details: - Click “Settings” - Find your material in the expandable tree in the left panel and select it - Enter your material thickness to the nearest .001” - Click “Apply” (If “Apply” is grayed out, click on your material name again) - Click “OK”

• Click the “Relocate View” button and then drag the file wherever on the cutting table you would like to cut.

• Now, click the “Focus View” button and click where you dragged your file. The laser will move to this location.

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• Open the laser cutter lid and put your material down underneath the laser. The red light will help you place your material.

• Fire it up! Close the lid and hit the big green button. Keep your mouse over the Pause button in case something goes wrong. The pause button will stop the cut and allow you to resume it if necessary.

After it’s done, open the lid and inspect your test cut. Did it go all the way through? If so, you can now confidently cut your own file. If not, ask a TA to help you adjust your settings. You’ll use these same settings when you cut your actual file.

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5. Do your real cut

Finally! Time to do your real cut. Since you’ve just done a test cut, this should be straightforward. Load your file into Illustrator and follow all the same instructions for the test cut.

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Having problems?

First, check to see if these might fix them… Otherwise, grab the TA for help.

1. It’s not cutting through all the way! This is a problem with many potential causes. It could be a dirty lens, bad focus height, the wrong material selection, or mean that you need to adjust the settings manually.

Dirty lens… If you’re getting bad cuts, ask the TA to come inspect the lens with a flashlight and bendy mirror. They’ll know what you’re talking about. It could be that the lens is damaged and scattering the light improperly.

Bad focus height… Sometimes these laser cutters have trouble maintaining their z-axis zero calibration. A quick way to check the z-height calibration after poor cutting is to have the TA put the black and white plastic measuring stick on top of your material and see if the machine is really set to your material thickness. If not, the TA can reset the z-axis and hopefully that will fix your problem.

Wrong material selection… This isn’t to say that you’ve picked the wrong material (though please check that you haven’t!) but rather that the software, for whatever reason, didn’t process your selection properly. Have the TA check the power, speed, and thickness settings against the materials list in the back of this binder to make sure that everything was set correctly.

Barring these other things… If the above items didn’t fix your problem, you’ll need to decrease the cutting speed/boost cutting power manually. Ask the TA to show you how to do this.

****Note: Resist the temptation to boost the power by changing the thickness of your material in the software. DON’T DO IT. Here’s what happens when you do this:

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Power is increased, but the focus height is wrong - the beam diffuses and is less effective at cutting

Correct focus height gets you through the material with minimal kerf loss

You’re hitting the surface of the material with more power, yes, but it’s unfocused, so it will probably cut worse. What do you do instead? Well, you can manipulate two cutting variables: the power and the cutting speed. Usually, keeping the power constant and decreasing the cutting speed will yield the cleanest results. Certain materials (Duron especially) cut very badly at higher power settings, and other materials (like acrylic) are already set to cut at 100% power.

2. My cut lines are showing up gray in the software! Sneaky CMYK… Make sure your file is in the RGB color mode. Go to File > Document Color Mode to verify.

• If you need to change this, you will also need to reset the color of all of your cut/engrave lines, as there’s a color shift when changing color modes

• To speed that process, click on one of the paths whose color you need to change. Go to Select > Same > Stroke Color and this will select all identically colored paths in your document at once

Stroke width and color… Check that the stroke width is 0.072pt (.001”) and that the RGB color values are set correctly

Duplicate/hidden lines… It’s possible that you have duplicate lines in your document. Try clicking on one of your lines and deleting it - is there something underneath it?

Filled lines… When coming from SolidWorks, instead of creating a continuous contour, it exports your shapes in individual, disconnected line segments. This is fine, but it’s hard to tell if your lines have just a stroke color or if they’ve got a stroke AND a fill color. You want to make sure your lines do NOT have a fill color.

• To check this, select your cut lines and look at the Color panel or the color picker at the bottom of the toolbox. The hollow square should be red and the filled in square should be white with a single red line through it.

• If this isn’t the case, click on that square and hit the “/” key.

Compound Paths… If your lines are grouped (e.g. you click on one and it selects a whole bunch of them), check to see if they are a Compound Path.

• Go to Object > Compound Path > Release and do this as many times as you are able.

• You may need to do some cleanup after this to get everything looking right again.

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Image Weirdness… Do you have any images (jpg, gif, png, etc…) in your file? Sometimes you’ll need to etch the image first and then create a separate file with your cut lines. This is one of those weird things we don’t totally understand but causes fairly consistent problems.

Hail Mary… If all else fails, try copying and pasting your whole file into a new document. Weird things happen sometimes and this trick works on occasion.

3. The laser is double-cutting my lines! This is a tricky one, and we don’t know for sure what causes it.

• Make sure that you don’t have two lines stacked on top of one another. • Select the lines that are double cutting (or, to be safe, all of your lines) and open

up the Pathfinder by going to Window > Pathfinder.

• Click on the “Outline” tool ! and don’t panic when all of your lines disappear! They’re still there, you’ll just need to reapply your stroke color and weight.

4. The machine is unresponsive! Is the power on at the wall? Is the machine on? Is the red icon showing up in the dock? Is the usb cable plugged in? Usually when the machine isn’t responding to input, it’s because it’s turned off.

5. It’s telling me there’s no data!

Usually this means your artboard is too large. Click the Artboard tool ! or hit Shift+O to enter Artboard mode. Enter a width and height that are, respectively, less than or equal to 24” by 18”. Click any other tool or hit “V” to exit Artboard mode and try printing again.

6. The laser is not cutting at all, just shining a red light where it’s supposed to cut! This means that the laser cutter has detected that one of its doors is open. It won’t cut if it can’t verify that the machine is completely sealed and thus safe to run.

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6. Clean up after yourself and get a 5-minute shop job from the TA

This is not optional! Be a good PRL citizen!

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Appendix I: Allowed Materials

The following materials are OK to cut on the Room 36 laser cutters. For reference, cutting strategies and warnings are included for each.

Acrylic Max Thickness .25” Remove the protective paper/plastic on the material. Apply transfer tape to the BACK of the material to protect from smoke residue when cutting. Dampen the transfer tape with water when cutting THICK acrylic. Variations: For mirrored acrylic, cut with the mirror side facing UP. Put transfer tape on both sides of the material.

Duron Max Thickness .25” Only Duron purchased at the PRL is OK to cut. Duron can be tricky to cut, particularly the .25” thick sheets. Do not be tempted to cut at greater than 90% power, because it will char your workpiece. Slow down the speed to get a deeper cut instead. The cut edges are quite sooty. Be vigilant and make sure you are getting clean cuts and not gross charred cut lines. If you see excessive blackening around the cut, you need to adjust your settings and verify the focus is set correctly.

Hardwoods Max Thickness .125” Black Cherry, Pine, Poplar, Walnut, Ash, Maple, and Basswood all cut nicely. Other kinds of hardwoods may be toxic when cut, so do not assume that you can cut something that isn’t on this list. Put transfer tape on the front and back (unless you are raster etching - then only the bottom surface) to protect against smoke residue.

Birch Plywood Max Thickness .125” Use the kind sold at the PRL or at Woodcraft. The only birch plywood allowed is high-quality, aircraft-grade plywood. Put transfer tape on the front and back (unless you are raster etching - then only the bottom surface) to protect against smoke residue.

Corrugated Cardboard Max Thickness .25” This stuff is super flammable, so watch it carefully. Weights to hold it down are a good idea so it doesn’t flap around.

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Mat board Max Thickness .060” Cuts well with slight browning around the edges. Put transfer tape on the top and bottom surfaces to minimize smoke discoloration.

Chipboard Max Thickness .125” Strong, versatile, and cuts very well. Available in many thicknesses. Vector engraving looks a little better than raster etching.

Silicone Max Thickness .065” Very useful for creating gaskets or adding damping/padding to a component. Sticky-backed or unlined silicone sheets can be cut. It tends to leave a very chalky residue, so be careful to use the lowest power setting you can get away with. Also take care not to cut too much of this stuff, because it can gum up the filters quickly.

Cork Max Thickness .060” Another very flammable material, due to its voids, so watch it carefully. Different types of cork will cut differently, so be diligent while doing test cuts.

Card Stock/Art Paper Max Thickness .015” Use a weight to hold it down so it doesn’t flutter or move. Use the settings for Mat Board and enter the thickness. Cuts very quickly and cleanly with minimal smoke damage to the underside. Some art papers will turn interesting colors when raster etched or vector engraved. Use vector engraving to create fold lines.

Copy Paper Max Thickness .004” Like card stock/art paper, it cuts very well with minimal smoke residue on the back. Be sure to hold it down while cutting, as the fans will make your workpiece flutter. Hit Pause in the middle of your cut, if necessary, to shift the weights around.

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Foam Core Max Thickness .188”

WARNING: Foam core is responsible for almost all of the fires on the laser cutters.

BE VIGILANT!!! One thing you can do to minimize risk is make sure all of your features are greater than 1/2” apart from each other. Cutting foam core melts the foam interior at the cut line, and features that are too close together can quickly turn into kindling and then flames.

PHBV Max Thickness .25” Biopolymer material used in certain research labs. Cuts fine but smells weird.

Leather Max Thickness .125” Smells awful, but cuts nicely. Be sure to warn other users and make preparations not to cut when the lab is busy. There are many types of tanning agents and some are not safe to cut. Do tour research before bringing the material in.

Skid Tape Max Thickness .032” **Cut/Engrave Only** Useful for creating custom skateboard deck designs. Not seen often.

Felt Max Thickness .050” **Cut/Engrave Only** There are many kinds of felt - some denser than others, but most of them should be fine to cut. Some types of felt melt together along the seam where you’ve cut if you boost the power too high, so look out for that. Felt can be neat or frustrating to cut, depending on what you’re trying to do - the shapes you cut out won’t necessarily want to come out cleanly, so you can make a choice about leaving them in or cutting them out with a sharp x-acto knife.

Cotton Fabric Max Thickness .030” **Cut Only** Quick, clean cuts - smoke residue may be visible on lighter materials.

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Ripstop Nylon Max Thickness .020” **Cut Only** Cuts very well and seals the edges, as an added bonus! Be careful not to boost the power too high, or your kerf width will be huge.

Mylar Film Max Thickness .010” *Cut Only** Use the steel weights or some other low-profile weighted frame to hold the material down as it cuts. It has a tendency to curl up and flutter.

Kapton Max Thickness .040” **Cut Only** Kapton tape is a thin film with silicone adhesive backing. It is not frequently used but cuts well and is useful for electronics projects.

Anodized Aluminum **Engrave/Raster Only** The laser vaporizes the coated layer to expose the base metal. Yes, this means that if your aluminum is bare, the laser will do nothing to it.

Glass **Engrave/Raster Only** Doesn’t so much etch as it does create tiny fractures along the surface. Very thin glass can be cut so long as it’s sandwiched between two layers of transfer tape, but the edges are jagged due to the aforementioned fractures. The vinyl cutter is a great alternative - use it to cut a mask for bead blasting instead of trying to engrave/etch the glass on the laser cutter. There’s even a type of vinyl we carry called “Frosted Etched Glass” if you want to just apply a sticker instead.

Stone **Engrave/Raster Only** Surface turns white where etched. Can fill these areas with paint to create more contrast afterward.

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Appendix II: Forbidden Materials

These are the materials that are never allowed on the laser cutters in Room 36.

Hardwoods not listed as OK Other hardwoods fall into one of two categories. Either they’re too hard to cut with a 60W laser, or they are potentially toxic.

Low quality/Home Depot plywoods These plywoods are filled with voids (making them more flammable) and questionable fillers, which makes them cut badly and release noxious fumes.

Polycarbonate Releases dangerous fumes and cuts poorly.

PTFE Too many types of Teflon exist to know whether each one is safe.

PVC PolyVinyl Chloride releases poisonous chlorine gas fumes.

Delrin/Acetal This is one that absolutely requires gas assist (which the PRL does not have) to cut well. Also releases noxious fumes when cut.

Carbon fiber/Fiberglass/Circuit boards Releases noxious fumes and does not cut well.

Transparency sheets/Camera gels Turns to goo when cut and potentially releases noxious fumes.

Polypropylene (HDPE,LDPE, etc…)/Polyethylene Melts into a gooey mess when cut.

Styrene Releases noxious fumes and burns very easily.

Neoprene Contains chlorine and releases toxic fumes.

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Laser engravable rubber stamp material This is counterintuitive given its name, but we are not set up to handle that much gummy material removal. The etched material clogs up the filters rendering them useless and these are expensive to replace. Making a wooden stamp is a good alternative.

ANYTHING ELSE If you have something you want to cut but see no mention of it here, please ask the lab manager. Do not assume that your material is safe to cut without checking first. The lab manager has final say in what does and does not get cut in Room 36.

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