Thermally sprayed engine bores require surface preparation prior to coating to ensure adequate adhesion. Mechanical roughening methods, in which a fine-scale dovetail profile is cut into the bore wall, produce surfaces which are easily gaged and are attractive for high volume. The currently available mechanical roughening methods are finish-boring based processes in which a standard boring insert is replaced with a PCD insert in which the roughening profile has been cut by EDM. These methods require diameter-specific tooling and significant clearance at the bottom of the bore for tool overtravel and retraction. This paper describes a new mechanical roughening method based on circular interpolation rather on finish boring. This method uses two tools: a side cutting end mill with peripheral grooves, which cuts a series of concentric grooves in the bore wall through interpolation, and a rotary swage which deforms the grooves to produce an undercut. This method produces higher bond strength than current surface preparation methods, and does not require diameter-specific tooling or bottom clearance for tool retraction. Therefore it can be used in flexible production systems without excessive tool counts. It also permits roughening and coating only a portion of the bore (e. g. the ring travel portion), reducing steel wire and energy consumption and enabling the elimination of a bimetallic cut on the joint face of the block. Following a review of existing methods, initial concept testing, finite element analysis and optimization for profile dimensions, and adhesion test results for the new method are described. Low volume production experience from for a V8 engine is also discussed. Finally, tooling details and test results for the application of the method to flat surfaces (e. g. brake rotors) are reviewed.