Embodiments of the invention generally include a robot assembly comprising a robot operable to position a substrate at one or more points within a plane, and a motion assembly having a motor operable to position the robot in a direction generally parallel to a first direction. The motion assembly comprises a robot support interface having the robot coupled thereto, and one or more walls that form an interior region in which the motor is enclosed. The walls define an elongated opening through which the robot support interface travels, and the motor is operable to move the robot support interface laterally in the elongated opening. The motion assembly further comprises one or more fan assemblies that are in fluid communication with the interior region. The fan assemblies are operable to create a subatmospheric pressure in the interior region thereby causing gas to flow through the elongated opening into the interior region.