Undermount Slide

An undermount slide is a concealed drawer runner mounted beneath the drawer box rather than on its side walls. In cabinetmaking, it is a hidden bottom-mounted runner that requires specific drawer-box geometry, rear notching, and front locking clips. Because the hardware is buried under the drawer, precise setback, hole placement, and rear clearance are essential. This leaves the side surfaces visually clean while providing smooth extension and self-closing action when tolerances are properly controlled.

In a typical cabinet or millwork shop, undermount slides are installed using a fixed setback from the cabinet face, and the machining pattern is often driven by a 32 mm grid or dedicated jig. The critical datum comes from the drawer box bottom and front edge, not the decorative front, so CNC programs drill the slide-mounting holes directly from the part program. Drawer-box construction must match the slide family: side thickness, bottom groove location, internal clearances, and drawer-box width all affect whether the runner engages cleanly. Before committing to undermount hardware, the shop should confirm carcass squareness and drawer tolerances, because these slides have little room for error. When set up properly, they deliver a clean reveal, consistent extension, and smooth self-closing action. In production, this hardware is selected when appearance and predictable performance matter, but only if machining and assembly tolerances are controlled tightly enough to prevent binding, rack, or premature wear.