We present a mobile phone based augmented reality (AR) assembly system that enable users to view complex models on their mobile phones. It is based on a client-server architecture, where complex model information is located on a PC, and a mobile phone with the camera is used as a thin client access device to this information. With this system users are able to see an AR view that provides step by step guidance for a real world assembly task. We also present results from a pilot user study evaluating the system, showing that people felt the interface was intuitive and very helpful in supporting the assembly task.