3900 Series Bearing Adaptor for LEGO Axle (6mm OD, 5mm Length) - 12 Pack

3900-0005-0006 3900 Series Bearing Adaptor for LEGO Axle (6mm OD, 5mm Length) - 12 Pack is a practical set of twelve miniature plastic adapters that solve the compatibility problem between standard LEGO® axles and industrial bearings with an internal diameter of 6 mm. The adapter fits into the bearing and acts as a bushing that holds the LEGO axle tightly, ensuring smooth rotation.

Key Features:

• Bridge Between Systems: Allows you to use popular and affordable LEGO Technic axles in designs that use standard 6mm inner diameter bearings.
• Secure Lock: The relief cut design allows the adapter to snap into place inside the 5mm thick bearing, while flanges on the edges prevent longitudinal movement.
• Minimal Weight and Size: Each adapter weighs just 0.13 grams and is 5mm long, which has virtually no impact on the overall weight and dimensions of the assembly.
• Set of 12: Provides enough adapters for multiple projects or creating complex kinematic designs with multiple supports.
• Ease of use: No tools are required for installation—the adapter is manually inserted into the bearing, after which the LEGO axle easily fits into it.

For whom: For engineers, educators, and hobbyists who create hybrid robotics or model-making designs that combine LEGO Technic parts for rapid prototyping with more serious components (bearings, frames) for precision and durability.