Structure

Robits Structural Tubes

Tubes are the primary structural components of the Robits building system. Tubes form the frame of the robot and provide mounting points for gussets, plates, standoffs, motion components, and other hardware.

Robits tubes are made from 6061 aluminum, a standard lightweight but rigid material for robot structures. Each tube is manufactured with holes arranged on the Robits ½ inch pitch grid, which allows structural components to be attached without drilling or modifying the tube.

Tube Profiles

Robits currently uses three primary tube profiles. Each profile can be used for a variety of structural purposes.

0.5 × 0.5 in. Tube

The 0.5 × 0.5 in. tube is the basic building block of the Robits structure. The small profile makes this tube useful when space and weight are important considerations. This makes it useful for building almost every component in smaller metal robot structures.

1 × 0.5 in. Tube

The 1 × 0.5 in. tube is essentially a wider version of the 0.5 × 0.5 tube. Its 1 inch face has two rows of holes, while its 0.5 inch face has one row. The additional width makes this profile useful for more robust structural connections.

1 × 1 in. Tube

The 1 × 1 in. tube provides a larger structural profile and is specifically designed to integrate motion components into the robot structure. Two faces have two rows of holes, while the other two faces incorporate larger holes for bushings. These bushing locations allow components such as gears, pulleys, and motors to be supported directly by the tube. This makes the 1 × 1 tube particularly useful when the structure also needs to support a moving mechanism. The larger cross section also makes the 1 × 1 tube useful for major structural members where additional stiffness is desirable.

Building a Structure from Tubes

Robits tubes are not only used by themselves - they are combined with gussets, plates, beams, and hardware to create rigid assemblies.

A Robits connection point connects multiple tubes while maintaining their position relative to the grid. An L gusset can connect two tubes at 90 degrees, while an angle gusset can create a connection at a different angle. AndyMark provides several gusset styles specifically for structural construction.

Structural vs. Mechanism Tubes

Designing for robustness starts with a strong chassis with room to connect other structural pieces upwards. When creating a structural frame, tubes should be arranged so that they resist movement in multiple directions. A rectangular frame with only four members can deform into a parallelogram if the joints are not sufficiently rigid. Adding gussets and cross members helps prevent this movement.

Mechanism tubes should be lightweight for quick, easy movement, but supported by strong uprights and attachment methods. Be sure to consult the robot build rules each year for guidelines on frame perimeter guidelines and expansion rules.

This is the 2025-26 DECODE Robits Starterbot. Notice how 1 x 1 inch tubes are used throughout the DECODE starterbot through the chassis and catapult support, but 0.5 x 0.5 inch tubes are used for the structure beyond that, providing lightweight support higher up.

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Robits Structural Channels

In addition to square tube, the Robits system includes channel-shaped structural members. Channels provide a lightweight way to build robot structure while leaving one side open for access to hardware and mechanisms.

Robits has two primary channel sizes:

• 0.5 × 1 inch channel

• 2 × 2 inch channel

0.5 × 1 Inch Channel

The 0.5 × 1 inch channel is the smaller of the two channel profiles. It is useful when a structure needs more support than a small tube can provide. There are also 3 holes that allow attachment to a SAR330 Aluminum Slide for use in Robits Compact Linear Slide. The open channel shape makes it particularly useful for structural members where components may need to be mounted inside or along the channel. The 0.5 × 1 inch channel is a good choice when weight and space are important considerations.

2 × 2 Inch Robits Channel

The 2 × 2 inch Robits Channel is the largest structural member in the Robits system. Its large, open profile provides both structural support and space for integrating motors, bearings, shafts, and other motion components directly into the robot.

The 2 × 2 channel is especially useful when a mechanism needs to be built inside the structure. AndyMark offers a 2 × 2 Robits Channel Mount that nests directly inside the channel. The mount can provide mounting locations for bearings and other structure, including perpendicular connections. Its low-profile threaded mounting holes are useful when clearance is limited and a conventional gusset would interfere with the mechanism.

The Robits Mecanum Channel Chassis uses this approach, placing motors and bevel gears inside the 2 × 2 inch channel to create a more compact drivetrain.