1A: Onshape Fundamentals

Exercise #1: Simple Box Tube

For this exercise, you will be modeling a simple 2x1 with some holes in it. For this exercise, do not use any Featurescripts.

Box Tubes

In FRC, robot structures are typically constructed out of aluminum box tubing, similar to wood beams for a house. Aluminum box tubing is commonly found in 2"x1", 1"x1", and 2"x2" sizes with 1/8" (thickwall) or 1/16" (thinwall) wall thicknesses. Box tubing is typically referred to by its size, eg: 2x1, 1x1, and 2x2 (Spoken as "two-by-one", "one-by-one", and "two-by-two"). For the rest of the learning course, we will use this notation when referring to box tube.

Box Tube Example

2x1 thinwall tube forming part of a robot structure. (Photo Credit: FRC 3647)

Instructions

Navigate to the "Exercise #1 Box Tube" tab in your copied document and follow the instructions in the slides to complete your first exercise.

1. Start by sketching a center rectangle on the top plane. Notice that we put the origin of the part at the center of the tube so that we can leverage the default geometry later on.

2. Extrude the rectangle symmetrically, 2" tall.

3. Shell the block to turn it into a 1/16" wall tube.

4. Add the top holes. Set the centerpoint of the hole to be vertical with the midpoint of the bottom line, then Mirror the hole across, using the front plane as the mirror line. We are able to use the front plane to mirror since we intelligently placed the origin at the center of the tube in step 1.

5. Extrude the top holes to cut all the way through the tube.

6. Add the side holes. Create the layout for the side holes by creating a center point rectangle and turning it into construction geometry. Again, having the origin at the center of the tube lets us place the center of the pattern at the center of the tube.

7. Extrude the side holes to cut all the way through the tube.

8. Name the key sketches and part. You can set part appearances and materials by right clicking on the part instance. Set the material to be 6061 Aluminum. To see the mass of parts, use the Display Mass Properties Menu

Note

Some sketches and features have been renamed (i.e. "Tube Profile"). You can rename sketches and features by hovering over the name in the dialogue box and clicking the pencil icon, or right clicking a sketch or feature in the feature list and clicking "rename".

Verification

Make sure to have you and/or a more experienced member/mentor of your team review your CAD following the instructions on the previous page! Your box tube should weigh about 0.35 lbs.

Construction Geometry

Notice how we utilized construction geometry to define the location of the holes on the 2" face of the tube. Using construction geometry to assist with sketching makes your parts more parametric and betters conveys design intent compared to manually specifying the location of each hole with dimensions.