Transform your Otto into a functional workshop assistant!

Turn your Otto into a functional filament transport robot with a counterweight-balanced system for stable movement

UPDATE (April 10): Major Stability Overhaul:
Roof-Mounted Ballast: Relocated the counterweight system to the roof. This significantly lowers the risk of tipping and allows Otto to carry spools with actual filament remains. 
Balance_Helper_v2: Added a new front-ball spacer. It extends the front support by 2.5cm, providing much better physical leverage and rock-solid stability during movement.

UPDATE (March 30): Now featuring multiple counterweight sizes (21, 28, 35, and 42 M8 nuts) to ensure perfect stability for any empty spool on the market!

Key Features:

• Print-in-Place Design: No complex assembly of the arm required! The hinge system is designed to be printed as a single functional unit—perfect for beginners and experts alike.

• Servo-Powered Action: Fully compatible with the Otto expansion kit. The lifting mechanism is driven by a standard servo, allowing for fully automated spool management.

• Smart Counterweight System: To keep Otto stable while carrying heavy loads, this mod includes a stylish "Filament Roll" counterweight that screws onto his back. Pro tip: This weight can also double as a desk paperweight or a base for future modular attachments!

  

• Aggressive Aesthetic: The arm features a modern Hex-Grid pattern. It’s not just for strength—it’s optimized for a stunning dual-color look even without an MMU (just change filament at a specific layer height).

  

How to use:

1. Attach the arm to your Otto (Servo required).

2. Screw the filament-shaped counterweight to the back.

3. Code your Otto to approach, hook, and haul!

Hardware Required:

• 21x M8 Hex Nuts(or more): Used as internal ballast for the counterweight. This ensures Otto stays upright even when hauling the heaviest empty spools!

Software & Control

Fully customizable movement! Since every filament spool brand has slightly different dimensions and weights, this arm is designed to be easily calibrated.

• Control: The arm is powered by a single standard servo from the Otto expansion kit.

• Coding: You can use the official HP Robots Otto Web Blocks or Arduino IDE. Just program the servo to rotate to your specific "pickup" and "carry" angles.

• Tip: Start with a slow servo sweep to ensure a smooth lift and to keep the center of gravity stable!

The Story: Why I built the Spool Transporter

"My workbench was constantly drowning in empty filament spools, and I realized my Otto was just standing there, watching the mess. I wanted to give him a real job! I challenged myself to design a high-performance mechanical upgrade that tests the limits of Print-in-Place mechanics while remaining accessible to everyone. The result? A heavy-duty, stylish assistant that turns workshop cleanup into a robotic show."

Print Settings

• Layer Height: 0.15 mm (recommended for smooth joint operation)

• Perimeters: 3

• Infill: 20% (Grid or Gyroid)

• Supports: NO (Designed to be support-free!)

• Material: PLA or PETG

• Color Tip: For the Hex-Grid effect, set a filament change in your slicer at the layer where the internal grid begins to get that sweet two-tone look.

FAQ:

• Q: Can it carry a full spool?

• A: No, this is specifically designed for empty spools.