Z-clip

Overview

A Z-clip has two screw holes (one in the foot, one in the upper flange) and a bent tab. The tab drops into a slot cut in the inside face of the apron, near its top edge; the flange screws to the underside of the tabletop. The top is held down but can slide on the tab as it swells and shrinks. It is quick to fit and almost invisible, which is why makers of modern plain-sided tables like it.

Types and sizes

Steel clips are typically sold in one or two sizes; the tab is sized to a standard 1/8 in (3 mm) saw kerf, so a router-table slot cut with a 1/8 in bit works too. A zinc finish is standard. Because the tab only grips a narrow slot, it is less forgiving than the rotating Figure-8 tabletop fastener.

Where it is used

Contemporary-minimal and Scandinavian-modern tables with thin aprons and slab tops often use clips or buttons, since no hardware shows at the apron edge.

Choosing and sizing

Use one clip about every 300 mm (12 in) along each long apron, and one near each end rail. Where a screw would restrain a top from moving, use a slotted hole or oversize the pilot so the screw is not gripping tightly across the grain.

Installation

1. Cut a slot 3 mm (1/8 in) wide and about 10 mm (3/8 in) deep in the inside face of the apron, 6 to 10 mm (1/4 to 3/8 in) below the top edge, with a table saw or a router table.
2. Hook the tab into the slot and set the flange flat against the underside of the top; mark the screw hole.
3. Drill a pilot hole in the top, taking care not to drill through. Drive a short screw (No. 6 x 1/2 in, 3.5 x 13 mm) and check that the top can still be slid by hand.
4. On an end rail the top barely moves at the centre, so a clip there can be a tight fit; clips nearer the rail ends need the slot to be longer than the tab so the top can slide.

Wood movement and species

On a long apron the top moves toward and away from the apron, so the tab slides in and out of the kerf: cut the kerf several millimetres deeper than the tab so that it never bottoms out or pulls free through the seasons. Do not glue the top to the base. Top thickness of at least 20 mm (3/4 in) is needed to take the screws safely.

Common mistakes

• Slot cut too close to the top edge of the apron, leaving a weak lip that breaks.
• Screw too long: it breaks through the top face.
• Too few clips: the top rattles or lifts.

Related

• Figure-8 tabletop fastener: more tolerant of movement and needs no slot.
• Tabletop button: the shop-made timber equivalent.
• Wood screw: the screws used to hold the flange.