Ward off wobbly legs
A three-legged project will not wobble, regardless of slight differences in leg length, because the weight will always be distributed across all three. So consider this option for stools or small tables.
Use only wood that has dried to a moisture level of 10 percent or less. (A moisture meter measures this.) Wetter wood -- although it might feel dry to the touch -- will ultimately dry out and potentially warp, creating uneven legs or weaker joints.
Tall tables and chairs
The taller you make a table or chair, the more likely it'll wobble unless braced, especially in narrow or top-heavy projects. Place stretchers as low as possible to achieve the best stability, such as with the dining chair, top left, and hall table, below.
But it can sometimes be the opposite. Thin legs and long, unsupported lengths can cause the wobble at the top. In these cases, use thicker legs or add extra bracing (stretchers or aprons) at the top of the leg assembly. Our original design for the Pub Table had right-angled stretchers at the top and bottom, as shown in third photo right, yet it proved wobbly at the top. So we changed the design to include an X-shape support structure to stiffen the base as shown in the bottom photo.
Make chair rails and table aprons as wide as possible where they join the legs. If you prefer a "lighter" look, add an arch or similar decorative element to the rail or apron, as shown below.
If you build a large table using hanger bolts or similar fasteners for easy disassembly, apply a thread-locking compound, shown right, to ensure the legs stay firmly attached.
Avoid scooting a table -- especially across carpet -- because any catch could damage or weaken a joint and cause the leg to wobble. Instead, always lift projects and carry them, even if it means getting a helper.
Make sure the floor's not the problem
So you've built a chair or table and, even though the construction seems solid, it wobbles. Before attempting any drastic fixes, try this: Move it to another location and check again for wobble. The problem might be an uneven floor. And remember that carpet proves a great equalizer, negating slight wobble with its padding.
Loctite Threadlocker Blue 242: .2 oz tube, Lowe's Home Improvement, lowes.com.