Layout Sketch

Open the analogy: a layout sketch is like the blueprint walls of a house before you place furniture. In FRC we lay out wheelbase, frame perimeter, motor positions, and pivot points FIRST, then build bodies to match. The big win is single source of truth. Beginners tend to model each part in isolation and then nothing lines up. Show a finished swerve drivetrain and point out that every module sits on layout-driven points.

Right-click top of browser > New Component, rename it 'Layout'. Activating the component (double-click) means the sketch lives inside it and stays organized. Demo: Create Sketch > click the XY plane. Stress sketching on origin planes, not on a body face, so the layout never breaks if geometry changes. Common mistake: sketching on a random face and getting a broken reference later.

Use Center Rectangle so it stays symmetric about the origin — this matters because the robot's center of rotation lands on the origin. Type exact dimensions: many FRC frames are 26x26 or 27x27 inside bumpers. Remind them frame perimeter is the TUBE outline, bumpers stick out further and the field perimeter limit is 120 in including bumpers. Keep everything fully constrained — black lines, not blue.

This is the heart of the layout: the points and lines other components will snap to. For swerve, place four module centers inset from the corners — MAXSwerve and SDS modules have a known mounting inset. Use horizontal/vertical and symmetry constraints plus dimensions. Goal: the sketch turns fully black meaning fully defined. Blue means under-defined and geometry can drift. Have students drag a point — if it moves, it needs a constraint.

This is Fusion's version of Onshape Variables. Modify > Change Parameters > the green + under User Parameters. Name them clearly, give units (in). Then in a dimension, instead of typing 26, type frameWidth. Demo changing frameWidth to 28 and watch the frame and module points all move together. Huge for FRC iteration when the drive team wants a different footprint. Mistake: spaces or starting names with numbers — parameter names must be valid identifiers.

In a NEW component, start a sketch, then Sketch > Project/Include > Project (shortcut P). Click the layout lines/points you want; they come in as purple linked curves. Now extrude tube from them. The link is live: edit the layout, the projected part follows. Mention Intersect for getting a cross-section where a plane cuts the layout. Common mistake: redrawing geometry instead of projecting, which breaks the single-source-of-truth chain.

FRC standard drivetrain stock is 2x1 0.0625 wall aluminum tube. Extrude the projected rail line into a 1 in tall, 2 in deep tube — orient it correctly so the 2 in dimension is vertical for stiffness, depending on your design. Keep each rail or component named. Reinforce that the rail position came from the layout, so you never typed a frame coordinate twice. Mistake: extruding as Join into the layout component — keep parts in their own components.

Hygiene slide. A messy layout poisons everything downstream. Teach them to glance at color: any blue means under-defined. Watch the 'Sketch is fully constrained' message at the bottom. Name important points so projecting later is easy. Warn against the chain trap: projecting a body face into a sketch, then editing the body, breaks the sketch — always project from the stable layout, not from downstream geometry.