Brackets and mounts
Bean-Bag Launcher Swing-Arm Assembly (Exploded)
- Bounding box
- 1317.5 × 78.2 × 50.0 mm
- Engine
- Precision B-rep
- Parameters
- 42
- Published
- September 17, 2026
Download
Free to download and use. See the terms.
The prompt
Design a bean-bag launcher swing-arm mechanism for a small competition robot, compliant with a rule requiring the launcher to start each run fully unloaded (no pre-tensioned springs at rest). Parts and dimensions: 1. Base mounting plate: 80mm x 60mm x 5mm, material PETG or 6061 aluminum, 4x M3 mounting holes at corners (10mm inset). 2. Pivot assembly: 6mm steel shaft, 40mm long, supported by two 6x19x6mm flanged ball bearings pressed into the base plate side walls (20mm tall bearing towers). 3. Swing arm: 150mm from pivot center to cradle center, rectangular cross section 20mm wide x 6mm thick, 3D printed in PETG or carbon-fiber nylon. Crank point for servo link at 30mm radius from pivot, offset 90 degrees from cradle centerline. 4. Cradle (bean bag pocket): hemispherical scoop at arm tip, 70mm inner diameter, 15mm deep, wall thickness 3mm, to hold a 130mm diameter, 150-200g soft bean bag. 5. Drive servo: standard-size digital servo, minimum 20 kg-cm torque, 25mm servo horn radius, mounted on base plate adjacent to pivot. 6. Connecting link (crank arm to servo horn): rigid link, 40mm long, with two pivot holes (3mm) at each end, rotating the swing arm through a 100 degree arc (from a loaded/cocked position to full release). 7. Release bumper: rubber or foam bumper, 14mm x 14mm x 10mm, mounted at the arm's forward travel limit to absorb impact at full swing. 8. Optional light return spring (not for launch energy storage): torsion spring, 12mm OD, 1mm wire, ~0.15 Nm preload, only to return the arm to loading position between shots. Output: an isometric or exploded assembly view, plus one dimensioned orthographic sketch (side view) showing pivot height, arm length, swing angle, and cradle diameter. Label every part with its dimensions.
Parameters
| Name | Value | Range |
|---|---|---|
| Base Plate Length | 80 mm | 30 – 200 |
| Base Plate Width | 60 mm | 30 – 200 |
| Base Plate Thickness | 5 mm | 2 – 15 |
| M3 Mounting Hole Dia | 3.2 mm | 2 – 8 |
| Corner Hole Inset | 10 mm | 4 – 30 |
| Pivot Shaft Dia | 6 mm | 3 – 16 |
| Pivot Shaft Length | 40 mm | 20 – 80 |
| Bearing Tower Height | 20 mm | 8 – 45 |
| Bearing Tower Width | 14 mm | 8 – 40 |
| Bearing Tower Thickness | 10 mm | 5 – 30 |
| Tower Spacing (center-center) | 30 mm | 16 – 60 |
| Bearing Outer Dia | 19 mm | 8 – 40 |
| Bearing Bore | 6 mm | 3 – 20 |
| Bearing Width | 6 mm | 3 – 15 |
| Pivot to Cradle Center | 150 mm | 60 – 300 |
| Arm Width | 20 mm | 8 – 60 |
| Arm Thickness | 6 mm | 2 – 20 |
| Crank Radius from Pivot | 30 mm | 10 – 80 |
| Arm Pivot Bore Dia | 6.2 mm | 3 – 20 |
| Crank Pivot Hole Dia | 3.2 mm | 2 – 8 |
| Cradle Inner Dia | 70 mm | 30 – 160 |
| Cradle Depth | 15 mm | 5 – 45 |
| Cradle Wall Thickness | 3 mm | 1.5 – 8 |
| Servo Body Length | 40 mm | 20 – 70 |
| Servo Body Width | 20 mm | 10 – 40 |
| Servo Body Height | 36 mm | 15 – 70 |
| Servo Horn Radius | 25 mm | 12 – 45 |
| Servo Horn Thickness | 4 mm | 1.5 – 10 |
| Link Length | 40 mm | 20 – 90 |
| Link Width | 8 mm | 4 – 25 |
| Link Thickness | 3 mm | 1.5 – 10 |
| Link Pivot Hole Dia | 3.2 mm | 2 – 8 |
| Hole Inset From End | 6 mm | 3 – 15 |
| Bumper Length | 14 mm | 6 – 40 |
| Bumper Width | 14 mm | 6 – 40 |
| Bumper Height | 10 mm | 4 – 30 |
| Spring Outer Dia | 12 mm | 6 – 40 |
| Wire Dia | 1 mm | 0.5 – 3 |
| Number of Coils | 5 ea | 3 – 12 |
| Coil Pitch | 2.4 mm | 1.2 – 8 |
| Spring Leg Length | 12 mm | 4 – 40 |
| Exploded Layout Gap | 180 mm | 60 – 400 |
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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