Abstract: A router guide assembly which permits rectilinear movement of a router for cutting acoustic tile panels while providing a reveal edge along the cut edges. Quick and easy movement is provided by two railed carriage sub assemblies, one of which is carried by the other. Manually activated mechanical stops are provided on each carriage for selectively preventing movement in either orthogonal direction so that a linear cut can be made in the other direction. Lock down devices are included for holding a tile in place. The assembly also includes a plastic housing and skirt attached to the underside of a router mounting plate for collecting and directing the sawdust resulting from the cutting of a tile to a location remote from the router guide assembly. Numerical measuring scales are selectively located on the assembly and include calibrations so that a required offset for bit size is automatically included when measuring for a particular cut.