The paper establishes a set of machining rules for web-based manufacturing and discusses the guidelines for their classification and implementation. Rule checking is split into three levels, the Design Interface. Process Planning, and Machine Tool levels. Rules are placed in these different levels according the resources available and the inherent constraints of each level while maintaining their principle functionality. The implementation of rule checking on the CyberCut 3-D interface, a web-based manufacturing tool for machining, is discussed. The current implementation checks for the four most common conflicts between mechanical designers and manufacturing engineers.