3D Exercise 133
- Breno Cruz
- 1 day ago
- 2 min read
In this CAD tutorial we'll use the features:
1. Extrude
You start by sketching the rough, blocky 2D footprint of the linkage arm and extruding it into a solid base body. At this stage, the ends of the arm are likely just flat rectangles.
2. Full Round Fillet
This is a highly specialized tool that saves a massive amount of sketching time.
Function: Instead of defining a specific radius, you select three adjacent faces (like the top, end, and bottom of your rectangular arm). The software automatically calculates and strips away material to create a mathematically perfect semi-circle that is tangent to all three faces.
Mechanism Application: This is the absolute fastest way to create the perfectly rounded outer hubs on the ends of a connecting rod or pivot joint.
3. Hole
Instead of just drawing a circle and doing a "Cut Extrude," you use the dedicated Hole command (or Hole Wizard).
Engineering Intent: This tool is loaded with real-world machining data. You use it to punch through the center of your newly rounded hubs. You can instantly specify if the hole needs to be a clearance hole for an M8 bolt, a tapped thread, a counterbore for a socket head cap screw, or a countersink.
4. Revolve
While the main body was extruded, linkages often have rotational features integrated into them.
Function: You might use a Revolved Boss to add a raised cylindrical bearing journal to the side of the hub. Alternatively, you could use a Revolved Cut inside the bore of your new hole to machine a tiny internal groove for an O-ring or a snap ring.
5. Chamfer
Before this part goes to an assembly (either digital or physical), the edges of the holes need to be treated.
Function: Applying a chamfer to the sharp rim of the precision holes creates a "lead-in." In the real world, this ensures a pin, shaft, or bearing can be smoothly pressed into the linkage without catching or shaving the metal.
6. Fillet
With the main geometry and precision holes finished, standard fillets are applied.
Function: You run standard radius fillets along the long edges of the extruded arm to relieve stress concentrations and make the part safe to handle during manufacturing.
7. Mirror
If the linkage is perfectly symmetrical (like a central rocker arm), you would have only modeled one half of it.
Function: As the final step, you mirror this entire complex, feature-rich body across the center plane to complete the part. This guarantees perfect alignment between the two sides.
All dimensions are in mm/g/s/ISO
3D Sketch
Exercise 133 - 3D practice drawing for all CAD software ( AutoCAD, SolidWorks, 3DS Max, Autodesk Inventor, Fusion 360, CATIA, Creo Parametric, SolidEdge etc.)
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Tutorial In Autodesk Fusion: https://youtu.be/5kh6C6BXF1E