Gears and transmission
Brachiating Robot Two-Link Arm Assembly
- Bounding box
- 620.0 × 50.0 × 140.0 mm
- Engine
- Precision B-rep
- Parameters
- 42
- Published
- October 21, 2026
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The prompt
# Fusion 360 CAD Design: Brachiating Robot Help me design a complete, manufacturable two-link brachiating robot in Autodesk Fusion 360, compatible with my MuJoCo simulation. ### 1. Structural arms Design **two identical arms** with: - Pivot-center-to-pivot-center length: **250 mm** - Width: **31 mm** - Thickness/depth: **51 mm** - Rounded ends and reinforced mounting regions. - One end connected to a gripper and the other to the elbow joint. Keep both arms geometrically identical. Consider hollow or ribbed construction to reduce weight while preserving the specified external dimensions. ### 2. Geared elbow mechanism I am using an **ST3215 servo motor** mounted on Arm A to drive Arm B through an external spur-gear reduction. Explore a preliminary 3:1 gear pair: - Pinion: 16 teeth - Driven gear: 48 teeth - Module: 1 mm Center the large gear on the elbow pivot and attach it rigidly to Arm B. Mount the pinion on the servo output. Include a separate structural pivot shaft, bearings, spacers, and a servo mounting bracket. Verify the exact servo dimensions and spline before finalizing the design. ### 3. Grippers Include two grippers at the outer ends of the arms. They must be capable of gripping overhead pegs and have secure, replaceable mounting interfaces. ### 4. Complete assembly Create separate Fusion 360 components for both arms, servo, bracket, gears, elbow pivot, bearings, hubs, grippers, and fasteners. Use appropriate rigid and revolute joints, and check gear engagement, elbow motion, clearances, and interference. Keep the design consistent with my simulation: **250 mm arm length and 150 mm peg spacing**. ### 5. How to guide me Teach me to build the CAD **step by step**, starting with the structural arm and then the elbow mechanism. Explain sketches, dimensions, constraints, extrusions, holes, and assembly joints. Do not invent unverified hardware dimensions. Provide dimensioned drawings and consider mass, strength, manufacturability, and motor torque. The required arm dimensions are fixed unless you explain why a change is necessary and ask me first.
Parameters
| Name | Value | Range |
|---|---|---|
| Arm length (pivot-center to pivot-center) | 250 mm | 100 – 500 |
| Arm width | 31 mm | 10 – 80 |
| Arm depth (thickness) | 51 mm | 10 – 100 |
| Arm centerline Z offset from elbow mid-plane | 32 mm | 0 – 100 |
| Lightening hole diameter | 14 mm | 4 – 30 |
| Lightening hole count | 3 pcs | 0 – 8 |
| Gear module | 1 mm | 0.5 – 3 |
| Pinion teeth | 16 pcs | 8 – 30 |
| Driven gear teeth | 48 pcs | 20 – 100 |
| Gear face width | 8 mm | 3 – 20 |
| Driven gear bore diameter | 10 mm | 4 – 20 |
| Pinion bore diameter | 6 mm | 3 – 12 |
| Servo body length (assumed) | 40 mm | 20 – 80 |
| Servo body width (assumed) | 20 mm | 10 – 50 |
| Servo body height (assumed) | 20 mm | 10 – 50 |
| Servo output shaft diameter (assumed) | 6 mm | 3 – 12 |
| Servo output shaft length (assumed) | 30 mm | 5 – 60 |
| Bracket length | 60 mm | 30 – 100 |
| Bracket width | 34 mm | 20 – 80 |
| Bracket thickness | 6 mm | 2 – 15 |
| Bracket bolt hole diameter | 3 mm | 2 – 6 |
| Bracket bolt hole inset from edge | 6 mm | 2 – 12 |
| Gripper length | 60 mm | 30 – 120 |
| Gripper width | 35 mm | 15 – 80 |
| Gripper height | 25 mm | 10 – 60 |
| Gripper jaw gap | 16 mm | 5 – 40 |
| Gripper mount hole diameter | 4 mm | 2 – 8 |
| Gripper mount hole spacing | 20 mm | 10 – 40 |
| Elbow pivot shaft diameter | 10 mm | 4 – 25 |
| Elbow pivot shaft length | 140 mm | 80 – 250 |
| Bearing outer diameter | 20 mm | 10 – 40 |
| Bearing inner diameter | 10 mm | 4 – 20 |
| Bearing width | 5 mm | 2 – 12 |
| Spacer outer diameter | 16 mm | 8 – 30 |
| Spacer inner diameter | 10 mm | 4 – 20 |
| Spacer width | 4 mm | 1 – 10 |
| Driven gear hub diameter | 30 mm | 15 – 60 |
| Driven gear hub length | 24 mm | 10 – 50 |
| Pinion hub diameter | 12 mm | 6 – 30 |
| Pinion hub length | 12 mm | 4 – 30 |
| Fastener head diameter | 5.5 mm | 2 – 12 |
| Fastener head height | 2 mm | 0.5 – 5 |
Every value above is a live dimension. Open a model like this in the editor and each one becomes a slider you can drag before exporting.
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