CAD & Engineering Drawing Cheatsheet

Cheatsheet Content

Global Pro-User Shortcuts S Key: Context-sensitive shortcut bar (Sketch, Part, Assembly). F Key: Zoom to Fit. Ctrl + 8: Normal To (rotates view flat to selected face). Ctrl + 7: Isometric View. Mouse Gestures: Hold Right-Click and drag (customize for Line, Trim, Circle). Module 1: Engineering Drawing (Manual & Theory) Conceptual Basics Angle of Projection: First Angle (India/Europe): Object between Observer and Plane. Third Angle (US): Plane between Observer and Object. Scaling: Understand strict scales (1:1, 1:2, 2:1). Module 2: 2D Drafting & Constraints Essential Keyboard Shortcuts L: Line C: Circle R: Rectangle D: Smart Dimension (for "Fully-Constraint"). Trim: Power Trim (hold click and drag). Conceptual Basics Constraint Color: Blue: Under-defined (Bad, can drag). Black: Fully-defined (Good, coordinates locked). Yellow/Red: Over-defined (Error, delete conflicting dimension/relation). Geometric vs. Dimensional Constraints: Use Geometric first (e.g., Parallel, Equal) for robustness. Module 3: 3D Modeling Shortcuts & Tricks Instant3D: Drag faces to resize extrusions dynamically. Enter Key: Repeats last command. Ctrl + Drag Plane: Creates new offset plane instantly. Conceptual Basics Selection Procedure: Learn "Tangency" (chain of edges) vs "Loop". Hole Wizard: Always use for standard holes (transfers manufacturing data). Never use Extrude Cut. Module 4: Drafting and GD&T Shortcuts Shift + Drag Dimension: Moves a dimension. Ctrl + Drag Dimension: Copies a dimension. Conceptual Basics GD&T Datum Feature: Anchors (A, B, C). A=flat base (3 pts), B=edge (2 pts), C=stop (1 pt). Fits: Clearance: Bolt goes through hole easily. Interference: Pin pressed/hammered in. Transition: Snug fit. GD&T Decision Table: Form (No Datum Required) You want to ensure... Symbol to Choose Student Project Example A surface is perfectly flat (not warped). Flatness Robot chassis battery sits level. A cylindrical pin or shaft is perfectly round (no ovality). Circularity (Roundness) Rotating shaft in gearbox; prevents vibration. A cylinder is straight along its axis (not bent). Cylindricity Long piston rod or lead screw. A line on a surface is straight. Straightness Edge of a ruler or a sliding rail guide. GD&T Decision Table: Orientation (Datum Required) You want to ensure... Symbol to Choose Student Project Example Two faces are perfectly parallel (constant distance). Parallelism Top/bottom faces of a mounting plate; sensor sits level. A pin or hole is at exactly $90^\circ$ to a surface. Perpendicularity Hole for a bolt; bolt head seats flat. A surface is at a specific angle (e.g., $45^\circ$) to another. Angularity Chamfered face or a V-block fixture. GD&T Decision Table: Location (Datum Required) You want to ensure... Symbol to Choose Student Project Example A hole is exactly where the drawing says it is. Position Bolt holes on two mating flanges (most common). Two cylinders share the exact same center axis. Concentricity Stepped shaft where a bearing slides smoothly. A surface rotates without wobbling relative to an axis. Runout (Circular) Brake disc or flywheel; checking for "wobble." Fits & Roughness Quick Guide Fits (The "Hole Basis" System) Slide / Free Movement: Clearance Fit (e.g., H7/g6) Use for: Shafts rotating in bushings, sliding mechanisms. Locating / Stationary: Transition Fit (e.g., H7/k6) Use for: Gears keyed to a shaft, pulleys that shouldn't wobble but can be removed. Permanent / Heavy Load: Interference Fit (e.g., H7/p6) Use for: Press-fitting a bearing into a housing. Surface Roughness (Ra) Ra 12.5 – 25 $\mu$m: Rough casting or flame cut (No machining). Ra 3.2 – 6.3 $\mu$m: Standard machining (Drilling, Milling). Good for general sides. Ra 0.8 – 1.6 $\mu$m: Fine machining (Grinding, Reaming). Mandatory for bearing seats and bushings. Ra Super fine (Polishing/Lapping). For sealing surfaces or mirrors. Module 5: Assembly and Sheet-Metal Tricks for Speed Smart Mates: Hold Alt + drag face to face for auto-mate (Coincident/Concentric). Tab / Shift + Tab: Hover over part, Tab to hide, Shift + Tab to show (good for internal parts). Copy Parts: Hold Ctrl + drag part from graphics area or tree. Conceptual Basics Top-Down Assembly: Designing a part inside assembly using references from other parts. Unbent View: "Flat Pattern" - crucial for laser cutting. Relies on "K-Factor" (material stretch during bending). Module 6: Surfacing Tools Concept Solid vs. Surface: Solid has volume (mass), surface has zero thickness. Knit Surface: "Zipper" - multiple surface patches knitted together. If watertight, SolidWorks can turn it into a Solid. Zebra Stripes: Visualization tool to check surface smoothness (curvature continuous) or sharp creases.