Popular Woodworking 2006-08 № 156, страница 25

Power-tool Joinery

Keep Your Tabletops Flat

Battens: Just one proven method to keep you on a level playing field.

The best way to keep a tabletop flat is to make it flat in the first place and to attach it properly to a rigid frame, such as that formed by a leg-and-apron assembly. But not every tabletop is attached to a frame. Trestle tables, pedestal tables, even drop-leaves lack frames to stiffen the tabletops and keep them flat.

Two common constructions effectively prevent cupping of a tabletop or of individual boards in one. The first is a batten attached or joined to the underside of the tabletop. This column will show you how to do that. In my next column I'll cover the other - a breadboard end joined to each end of the top.

Batten Basics

So what is a batten? The idea is simple. You attach a stiffener across the grain of a board or panel to counter any tendency of it to cup. The batten has to be strong enough to resist the board's cupping power, as does the method of attachment. In addition, you must allow for expansion and contraction of the board or panel. It's common to use two or three battens per board or panel.

The drawing at right shows two basic options: Attach each batten with three screws or with a sliding dovetail. No glue is used. The obvious advantage of using fasteners is that you can cut and mount each batten quickly. In addition, a batten secured with screws can be relatively unobtrusive; cut it 3" or 4" shorter than the table's width so it can be set back from the table's edges.

The primary difficulty in using screw-mounted battens is elongating the clearance holes to allow the wood to move freely. You can enlarge drilled holes with a small-diameter

by Bill Hylton

Bill is the author of several books about furniture construction and router operations. When he isn't writing about woodworking, he's doing it in his home shop in Kempton, Pennsylvania.

A stout batten joined to the underside of the tabletop with a sliding dovetail will keep the top flat. Here, the batten extends to the very edge of the tabletop. In winter, when humidity is low, the top will shrink, and the batten will protrude very slightly. In summer, when the top swells, the batten end will be slightly recessed.

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