9358138 Ziegert This research project will consider the dual problems of accuracy assessment and accuracy enhancement. In principle, if the positioning errors at each location in the workspace of the machine are known in advance, they can be corrected in software. To accomplish this, the causes of the errors must be isolated and studied. These error sources include manufacturing tolerances of the machine slides, deformations caused by heat, and deflections due to gravity. Software based error correction offers a large potential economic payback. Commodity grade machine tools may be able to achieve substantially higher accuracy levels at a very modest cost, thus making them competitive with more expensive machines specifically designed for high precision work. Successful completion of this research project may help the US machine tool companies to regain a competitive advantage.