Shafts

Shafts are rotating componentselements used to transmit torque andthrough supporta movingrobot’s mechanismsmechanisms. In FRC, different shaft geometries are used depending on anhow FRCsecurely robot.components Theymust aretransfer commonly used with gears, pulleys, sprockets, wheels,motion and rollers.how much load the system experiences.

Common Shaft SizesTypes

Typical

1/2" Hex Shaft

• Most common FRC shaft sizestype
include:
• Torque is transmitted through flat faces
• No slipping when used with matching hubs
• Easy to assemble and align

3/8" Hex Shaft

• Smaller, lighter hex shaft option
• Used in compact or low-load mechanisms
• Easier to package in tight designs
• Lower torque capacity than 1/2" hex

1/2" Round Shaft

• Smooth cylindrical shaft
• Requires keys, pins, or set screws for torque transfer
• Can slip if not properly constrained
• Used when free rotation or simple pivots are needed

Spline XL Shaft System

Spline XL is a high-torque shafting system used in FRC for demanding applications.

Key Features:

• Multiple splines (teeth) around the shaft
• Very high torque capacity
• Prevents slippage under heavy load
• Allows precise, repeatable component alignment

Why Teams Use It:

• Handles extreme drivetrain loads
• More robust than hex shafts in high-stress systems
• Reduces wear from repeated high-torque cycles
• Improves long-term reliability

How They Relate

• Round shaft → simplest, lowest torque transfer (needs retention features)
• 3/8" hex shaft→ compact, moderate torque, space-saving option
• 1/2" round shaft

Among these, 1/2" hex shaft→ isstandard thebalance most common because it allows components to directly transmit torque without additional keys or set screws.

Common Materials

Shafts are typically made from:

• Steel for highof strength and wear resistanceusability
• AluminumSpline forXL lightweight→ applicationsmaximum torque capacity and reliability

SteelAs shaftsload arerequirements mostincrease, commonteams becausetypically theymove resistfrom bendinground and→ twistingsmaller underhex load.→ 1/2" hex → spline-based systems.

Common Applications

Shafts are used in:

• Drivetrains (1/2" hex, Spline XL)
• Intakes and rollers (3/8" and 1/2" hex)
• Elevators and arms (1/2" hex, Spline XL)
• Gearboxes
Light
• Wheel assemblies

Important Properties

• Strength: Resists bendingpivots and twisting
mechanisms
• Stiffness:(round Prevents deflection under load
• Wear resistance: Handles bearings and rotating components
• Weight: Larger shafts provide more strength but add mass

Common Mistakes

• Using a shaft that is too small for the load
• Allowing unsupported shaft spans to become too long
• Improperly retaining the shaft
• Misaligning bearings and shaft supportsshaft)

Key Idea

ShaftsShaft transferselection powerdepends throughouton antorque, FRCpackaging, robot.and Selectingreliability needs. 3/8" hex is a compact option, 1/2" hex is the properstandard, size,round material,shafts require additional retention, and supportSpline methodXL ensuresis reliableused when maximum torque capacity and efficientdurability mechanisms.are required.