Four-Bar Linkage (Crank-Rocker) Design in FreeCAD | Master Sketch + Grashof

Master parametric design by creating a four-bar linkage — configured as a crank-rocker, with spreadsheet-driven parameters in FreeCAD. A single rotating shaft can drive a windshield wiper, a rocking sprinkler, or a walking robot leg with the same basic mechanism: four rigid links and four pin joints. The difference between smooth motion and a mechanism that locks up comes down to link length ratios, exactly what Grashof's Theorem predicts. In this build we use, master sketch techniques and expression-driven dimensions, then verify Grashof's condition to guarantee full rotation of the input crank. What you'll learn: • Create master sketches for kinematic layout control • Apply construction geometry as reference for multiple parts • Implement spreadsheet-driven parametric mechanisms • Understand Grashof's Theorem and link length relationships • Assemble pin-jointed linkage systems with motion verification Real-world applications: vehicle suspensions, excavator arms, door hinges and folding mechanisms, windshield wipers, robotic arm joints, adjustable furniture. 📖 Full written lesson (free): https://siliconwit.com/education/para... 🧪 Try the interactive simulator first: https://siliconwit.com/product-develo... 🎓 Full course: Parametric Mechanical CAD with FreeCAD: https://siliconwit.com/education/para... #FreeCAD #FourBarLinkage #GrashofTheorem #MasterSketch #CrankRocker #ParametricDesign #MechanismDesign #CAD #SiliconWit Join our community and stay up-to-date with the exciting worlds of engineering, computing, science, and philosophy. 🌐 Website: https://siliconwit.com/ 🔗 Linktree: https://linktr.ee/siliconwit 📂 GitHub: https://github.com/SiliconWit 💬 Discord:   / discord   📘 Facebook:   / siliconwit   👥 Facebook Group:   / 5984180241640422   📸 Instagram:   / siliconwit   🎵 TikTok:   / siliconwit   🐦 Twitter:   / siliconwit   👔 LinkedIn:   / siliconwit   🔴 Reddit:   / siliconwit   💡 Quora: https://www.quora.com/profile/SiliconWit 📌 Pinterest:   / siliconwit   📺 YouTube:    / @siliconwit