This Instructable is designed to be a friendly project-oriented walkthrough for users new to Inventor or CAD in general. If you want to start using Inventor like all the cool kids, but feel overwhelmed by the panoply of features, options, and tools, start here!

We'll learn about:
Sketches and parts
Setting the Heads-Up Display and using it to define dimensions
Drawing lines
Using the Mirror tool

Plus, you'll have a design for a pair of handy test pieces to help you figure out how to size your laser-cut boxes so they snap together just the way you want! (To make the combs, continue through Exporting Inventor Files to CorelDraw [forthcoming], then cut them on your handy local laser.)

Step 1: Make a New Part

First, fire up Autodesk Inventor and create a new standard part. A "part" consists of one or more sketches. These sketches define one aspect of a part, such as the shape of one face of a part or the contour of a machined edge.

Select Standard.ipt and click OK to start a new sketch.

Step 2: Check Settings

Check to see that the Heads-Up Display is on and set correctly (for the purposes of this Instructable):

1. Click on "Options" at the bottom of the Inventor menu.

2. Click the Sketch tab and make sure that "Enable Heads-Up Display (HUD)" is checked.

3. Click "Settings" and set Dimension Input to Polar Coordinates. Click OK.

4. Remember to click "Apply" in the Application Options window, then "Close".

There are lots of other settings in here too, as you can see. Take a look and remember them for later when there are other things you want to change!

Step 3: Draw a Tooth

1. Select the Line tool from the upper left of the window.

2. Starting at the origin (where the two darker grid lines meet), click to start drawing a line segment. The Heads-Up display will appear. Enter the thickness of your material as a decimal (mine was .122"). If you don't know how thick your material is, get some calipers and measure it!

3. Click to anchor the segment. Then we'll make another segment perpendicular to the first. Type .505 to make the first tooth .505 inches wide.

4. Click to anchor this segment. Draw another segment back down to the X axis. First tooth complete!

Step 4: Draw More Teeth and Gaps

Continue drawing teeth and notches of slightly increasing sizes. Whee!

I made all my teeth larger than any of the notches. Even a laser removes a little bit of material, so the teeth will need to be larger than the gaps in order to fit snugly.

Step 5: Create Comb Body

1. Anchor a line segment at the end of the last tooth.

2. Draw a segment to form the body of the comb. (Mine is .5".)

3. Draw a segment over to the Y axis and anchor it.

4. Draw a segment that ends at the edge of the first tooth.

Step 6: Make an Inverse Comb

Now say we want to make some notches and teeth of different sizes. We can't mirror the whole comb or we'll have the same thing. Instead of redrawing the comb, we can invert just the "teeth" edge and draw a new comb body.

1. Select "Mirror", then click Select.

2. Select the teeth-and-notches part of the comb.

3. Then click Mirror Line, and click on the bottom line segment of the comb.

4. Click Apply, then Done.

5-8. Draw in the rest of the comb body by anchoring line segments to the edges of the notches and drawing the flat edge of the comb.

Step 7: Finish Sketch!

Woohoo!

1. Click Finish Sketch on the far right of the toolbar.

2. Don't forget to save your work!

Ready to cut? Go on to Exporting Inventor Files to CorelDraw (forthcoming) to get ready for the laser!