Laser Cutting Guide

1. You MUST have either a Normandale professor or Lab Assistant at least in the same room with you when cutting *(more into this below)
   
2. When using the cutter please fill out the laser cutter log with the right info (name, date, reason: STEM Club, etc.)
   
3. For your first cut you need to have someone with you to show you how to use the equipment: focusing the laser, running the ventilation that MUST be on, and how to use the cutter software
   

The laser cutter itself is rather simple, it's what you can do with it that gets complicated. The laser cutter functions like a normal printer in that you "print" specialized .pdf files to it and it it cuts the material instead of printing what it sees. To prepare these .pdf files I recommend the free, open source program Inkscape (download here). I also recommend you grab the portable version here and install it on a flash drive or similar so you always have it with you. If for some reason you don't want to use Inkscape any vector graphics editor (such as Adobe Illustrator) should theoretically work but I have no experience with them. Whatever the project you're working on you'll always end up preparing the final images with Inkscape before sending them to the cutter. You have to use vector graphics software to design the .pdf's for the cutter. I don't really want to explain the differences with vector graphics vs normal images (raster) so I recommend you read the explanation here. Long story short the laser cutter needs a solid path (available only to vector graphics) to follow in order to actually cut a line vs cutting a small hole for every pixel in the line in your image (what you get with traditional raster images).

Additionally, the only difference in cutting vs engraving is speed and power. To cut you maximize the power and slow the speed, to engrave you crank the speed up and lower the power. The cutter uses eight color 'profiles' of speed and power in order to know what to do for each line in your image (known as paths in vector graphics). Because of this the color of your shapes/paths are critical, when setting up to cut/engrave the software will read the colors you have and assign the 'profiles' it has set to those colors. You have eight colors to work with but two should generally be enough: blue means "cut this" and red means "engrave this."

As for material you should only be cutting wood. While the cutter can pretty much cut anything I'm told Normandale only likes to use wood in it since other materials tend to stink up the whole science building. The maximum thickness you should ever be cutting is 1/2" hardwood (oak boards, etc) but you should always try and stay under 3/8" unless you really need something thicker. I myself like to use this really nice 1/4" hardwood plywood I found at Home Depot. If you end up working with me this will probably be what you'll use since I had a 4' x 8' sheet cut up for the club. Also the maximum sheet size for both the cutters is 1' X 2'


2D Object from Inkscape:
I'll use a past project of mine to explain how to cut and engrave a simple 2D object. Everyone should do at least one of these to get the basics down.

Doing everything in Inkscape is by far the simplest method so you should try to use it first to draw out whatever you're making. I'm by no means an expert in Inkscape and I prefer using Autodesk Inventor to make my sketches so I cover that method below. I made the following to measure the kerf of the laser cutter with my plywood. The kerf is the width of material the laser beam burns away while cutting. Inkscape image with final product:



When designing a project in Inkscape you have to keep in mind what you want to cut vs what you want to engrave. After you have a polished product in Inkscape you now have to assign colors to each shape/path for the laser cutter. This is what the cutter uses to know what to do with each line. I only used two colors: one (blue) to indicate where the cuts are and the other (red) to indicate where the engraving is but you have up to eight different colors you can use to specify different settings for.

Some useful tips for when drawing in Inkscape:

• Save your work as you go! You should be saving your work in Inkscape as a .svg normally, you only save as a .pdf when going to the cutter!
  
• To change the size of your document click File then Document Properties and use the Custom size box, the max size you should use for the laser cutter is 23.5" wide by 11.5" high
  
• Group paths/shapes as you go by hitting Ctrl+G, you can always ungroup any groupings you make by hitting Ctrl+Shift+G
  
• You can make guidelines by clicking on and dragging from the rulers at the top and left of the screen, use these to line everything up - you can 'snap' to these when drawing by using the snap buttons on the right side of the screen
  
• When drawing or creating shapes Inkscape will show you useful options at the bottom of the screen. Example: when drawing with the main pen tool (Shift+F6), you can hold Ctrl to snap the lines to 15 degree increments
  

1. After it's all said and done in Inkscape hit Ctrl+A to select everything.
2. Click Object at the top, then Fill and Stroke
   
3. Under the Fill tab set it to No fill (the X button), if this causes some objects to disappear hit Ctrl+Z to undo it then do steps 4-11 first
   
4. Now go through your image and select everything you'd like the laser to cut (shift + click or shift+click & drag)
5. I recommend you create a group of these objects, so while you have them all selected hit Ctrl+G
   
6. Under the Stroke paint tab (in Object -> Fill and Stroke) set it to Flat color (first square)
7. Set both the A (Alpha) and B (Blue) bars all the way to the right (255) and the other two to the left (0)
8. Now go through and select what you want to engrave
9. Group it by hitting Ctrl+G
   
10. Under the Stroke paint tab set it to Flat color (first square)
11. Set both the A (Alpha) and R (Red) bars all the way to the right (255) and the other two to the left (0)
12. Go back to the image and hit Ctrl+A to select everything
    
13. Under the Stroke style tab (in Object -> Fill and Stroke) set the units to inches and the width value to 0.001". The rounded join and cap options here can help clean up your paths if necessary too.
14. Now click File, then Save As
15. Name it whatever you want but be sure to switch the type under File name to .pdf (you should be saving your image as a .svg normally)
    
16. Click Save then OK in the window that pops up.

You now have a .pdf ready to be sent to the cutter! Bring the .pdf in on a flash drive or similar and I can show you how to run the cutter with it.

2D Object from Autodesk Inventor:

1. With Inventor still open click the Inventor Pro icon in the top left of the program
2. Click the little arrow next to New and then click Drawing
3. In the left pane select and delete both 'Default Border' and 'ANSI - Large'
4. Click the Base button at the top left
5. It should have automatically loaded your part but if not find it real quick under 'File'
6. Choose the correct orientation in the right-hand box (this depends on your specific project, for example mine was Top) then click OK
7. You should now have an outline of your project in the drawing and a 3D model following your mouse cursor
8. Right click and click cancel or hit escape to get rid of it
9. Click the Inventor Pro icon at the top left again and click the little arrow next to Save As, then click Save Copy As
   
10. Find where you want to save it and name it whatever you want, then set the Save as type to DXF Files (*.dxf) and save it
    
11. Open Inkscape and open the .dxf file you just saved
12. Assuming you used inches in Inventor, set the manual scale factor in the popup window to 25.40 (although you can change the sizing in Inkscape later)
13. Use the outline in the previous example to make an .svg and prepare the .pdf needed for the cutter.
    
14. NOTE: When importing the .dxf Inkscape likes to split your lines up into a million different paths so you should follow these two steps: 1. Hit Ctrl+A to select them all and under Object -> Fill and Stroke -> Stroke style tab switch the Join and Cap to their rounded options and 2. Group together broken paths and shapes by selecting them and hitting Ctrl+G, or just select everything by hitting Ctrl+A and then Ctrl+G
    

3D Object with Autodesk 123D Make

This method is probably the most complicated but gives you the coolest product. When explaining this process and the boxes below I'm going to assume you're pretty comfortable in Inkscape (especially grouping) and with preparing the .pdf for the cutter. The program you're going to need is made by Autodesk and called 123D Make, you can download it for free over here. Again, if you haven't already you should check out my post here about getting Autodesk software for free, if you've already done that and have your account info then you can keep going. If you don't have an Autodesk account you're going to have to register one to use the program (it's free).

The basic purpose of this program is to take 3D models and slice them up in order to build them up from 2D pieces. You can use their example shapes or import your own .stl or .obj files (from say, Autodesk's AutoCAD or Inventor) to work with. There are several techniques you can use but I'll only be covering the simple Interlocked Slices method, I've been playing around with Radial and Curve slices so I might update this later. Below is a simple torus design I made to get a feel for this process along with the Inkscape plans, unassembled pieces in the cutter, and finally the finished, assembled product (it got a little beat up when I was pounding it together, made it about 0.005" too tight):

Some tips for 123D Make

• When you goto save, save 'To Your Computer' instead of 'To My Projects' to save it locally on your own computer
  
• You can easily navigate with your mouse: click and hold your model with your mouse wheel to move it without rotating it, and right click it to hold it in position and only rotate it
  
• Keep an eye out for potential errors with your slices, potential problem slices are highlighted as either blue (not connected) or red (cutting errors), you can see details about the errors by going into the Model Issues tab on the right (if you don't see it click the little gear button under Manufacturing Settings)
  

To make this simple torus just follow these steps (they have a torus in their example shapes selection so don't worry about importing your own):

1. Start up 123D Make and sign in (top right)
   
2. Hover your mouse above the arrow next to 123D Make logo in the top left of the screen then above Open Example Shapes, click on Torus
3. Under Object Size on the left make sure it reads 8" wide by 8" long and that the Uniform Scale option is selected
4. Under Manufacturing Settings on the left click the little gear icon (layout panel should pop out on the right) and then click the pencil button (Manufacturing Settings window should have popped up)
   
5. Click the single + (plus sign) button at the bottom (a new preset should have been made, probably named: unnamed_0)
6. Click on this preset you just made and set the following values: Units - in, Material Size: Length - 40.000, Width - 40.000, Thickness 0.1850, Cutting Tool Parameters: Slot Offset - 0.010, Tool Diameter - 0.000, then click Done
7. Under Construction Technique on the left choose Interlocking Slices
8. You can play with the settings under Slice Distribution to get a feel for what each one does, generally you have two axis to work with for slices. I'd suggest leaving the Notch Factor, Notch Angle, and Relief Type at the default values (although a Notch Factor of 0.500 will help with assembly if you have a complex structure)
   
9. Next you can go into the Slice Direction, you can click and drag the blue cone and yellow disk to change the slice geometry. It's hard to describe this process as there's no right or wrong, I recommend you just spend some time working with this. There are a couple things to lookout for though since this is where most of the slice errors will come from, you can go into the Model Issues tab in the top right to see any potential problems as well
   1. First are blue slices - these are slices that aren't connected to the main body/shape by any other interlocking slices
   2. Next are red slices - these usually have problems with the interlocking notches that will make construction either more difficult or straight up impossible
   3. Also, since we're using a laser cutter you can generally ignore the error: "Notch intersects hole" if you have only ONE slice with this error. Otherwise assembly will most likely be impossible.
      
   4. The last thing to lookout for is some of your notches can get very long and end up almost cutting your slice in half. This can leave a dangerously thin amount of material holding a slice together, to check this go back to the Cut Layout tab in the top right and click on the sheet with your parts in it (see pic below)

   
   

   (notches 8 in slice Y-5 and 5 in slice Z-8 leave these slices very weak)
   

   
   
10. When you're happy with the slice distribution and direction, save it to your computer, then click Get Plans at the bottom
    
11. Change File Type to PDF and hit Export to save it wherever you want
12. Open this .pdf with Inkscape and hit OK in the window that pops up, NOTE: it won't look like anything will be there, the Stroke paint is unselected (hit Ctrl+A and change the Stroke paint to Flat color)
13. Now comes the fun part, you're going to have to go in and ungroup everything and set the letters to red (engrave) and the outlines to blue (cut), then group together the letters of each piece with its outline. You may have to move some of the labels around if they overlap.
14. You should resize your Inkscape document to 23.5" wide by 11.5" high (File -> Document Properties), this is the size of a sheet that will fit in the cutter. If you end up using more than one sheet you should make a new Inkscape .svg for each additional sheet
    
15. Now it's time to play tetris, try to rearrange your pieces to be most space efficient as possible. To rotate your pieces click them once to select them then click them again, the corner arrows should have changed. Click and drag these arrows to rotate your pieces to help with maximizing space efficiency.
16. If you haven't already, 123D Make includes a large box around all your pieces by default when it exports the .pdf, you can delete this
17. After you set the part outlines to blue and the lettering to red select everything and set the Stroke style width to 0.001"
18. Prepare the .pdf(s) for the cutter

NOTE: ALWAYS CUT TWO SMALL TEST SLICES FIRST TO MAKE SURE THE NOTCH SIZING IS CORRECT

Now you're good to go! After you cut out your slices you can go open up your model in 123D Make again and click Assembly Steps to get step by step instructions on how to build it or you can follow the lettering on the slices themselves - all the lettering for each axis faces the same way and the number on each notch corresponds to the slice number from the other axis that slides in it (for example: notch #4 on slice Z-2 connects to notch #2 on slice Y-4). Be careful when you have multiple slices per slice number (example: Y-2-1 and Y-2-2)!

Importing 3D models:

Alternatively you can import your own 3D models in .stl or .obj format to work with by simply clicking the Import... button instead of using their example shapes. Configuring the slices can get tricky with more complex 3D models so it'll take some experimentation to find out what works. TIP: Inkscape includes an extension by default that has a plethora of 3D models ready to use. To use these simply navigate to the following folder when importing (this might be different depending on your installation): C:\Program Files (x86)\Inkscape\share\extensions\Poly3DObjects

3D Boxes with BoxMaker/Inkscape Tabbed Box Maker Extension:
There are two methods to make all manner of boxes/cubes/etc. and both are rather similar, I'll cover both just to give people options. I'll probably come back and make step by step instructions too.

The first is on online tool known as BoxMaker, you can find it over here. After entering your settings it'll spit out a .pdf of your box you can then import into Inkscape. To use it simply goto the site, enter the outer dimensions you'd like for your box, the material thickness (in the case of the club's plywood it's .192"), and the cut width under advanced options (.007" for the cutter on campus). It should automatically set the notch length so you shouldn't have to mess with it unless you're doing something specialized. Hit Design It! and it should spit out your .pdf, you can save this to your computer or just open it in Inkscape. Once you have it in Inkscape you can either prepare it for the cutter or you can edit it further before preparing the .pdf. I'll post some examples of stuff I've made by simply getting the box outline from this and editing it further in Inkscape.

The second is an extension for Inkscape aptly named the Tabbed Box Maker, you can find the necessary files to add it to Inkscape over here. After you download it you should read the README file included just to get a feel for the different options. To 'install' it simply copy the two files boxmaker.inx and boxmaker.py to the Inkscape extensions folder (probably C:\Program Files (x86)\Inkscape\share\extensions). To access it in Inkscape just click Extensions at the top and navigate to Laser Tools -> Tabbed Box Maker... You can try out different settings to get a feel for the program but there are three settings you should keep consistent: Material Thickness should be set to 0.192", Kerf should be 0.007", and Clearance should be 0.000". Like the method above you can edit these further as you see fit and add text/designs/etc.

(To get corners like these candle boxes set the material thickness lower - I just think it looks cooler this way)