By Gary Rogowski
Rock-n-roll. That’s what four-legged pieces have a habit of doing – even with perfect joinery and a careful and unhurried assembly. Even with all the care and attention you paid to building it correctly, it doesn’t sit flat on your floor but moves back and forth rocking on two legs. What gives?
Don’t worry; it’s just life at the bench and Euclidean geometry raising its head again. If you build everything with three legs, you won’t have this problem. But because a lot of tables and chairs have four legs, you are constantly faced with this issue. Just a little pull from one of the joints and your chair or table doesn’t sit flat. The legs are still the same length but they’re pulled out of true or flat by your assembly.
Let’s say you need to remove a bit of length from one or two legs. As little as a 1⁄32″ or 1⁄16″ can be a lot to take off with a handplane, but too little to remove with a saw – even if you could line up your saw perfectly. So, how do you true the legs without either making your chair too short or making yourself frustrated in the process?
Let’s understand the problem first. A four-legged chair doesn’t sit flat for one of two reasons. It either sits on an uneven floor or the chair itself is twisted. How do you determine where the problem lies? As I tell my students and all my clients, my bench is the Center of the Universe. If it sits flat on my bench, then it’s flat. If it moves to the floor and rocks, it’s the floor. Of course you could move the piece around until it finds a spot where it’s not tipping then never move it, but that’s not a reasonable solution. So for all intents and purposes, my bench is my reference surface and sets the standard to which I work. If the piece sits flat on my bench, then it’s good to go out the door.
Four-legged pieces can twist for any number of reasons: too much clamping pressure on one side versus the other, mortises cut slightly off center from each other or tenons made at slightly different locations. Little things during construction can add up to small variations that result in a rock so bad in the piece that you think your wood is possessed. (Heck – the boards may actually be possessed and moved or warped as you cut them.) Clearly, this can affect your joinery. Any of these things can add up to a piece that seems to have two longer legs. Even if your legs are equal in length, your task is to trim the bottoms of the seemingly longer ones.
Video: Watch a short video on how this leg-shaving technique is done using a table saw.
Web Site: Visit Gary Rogowski’s Northwest Woodworking Studio site for information on classes and to view a gallery of his work.
Blog: Read about an alternate method to solve the wobbly four-leg syndrome.
In Our Store: Get our 76-page Essential Guide to Table Saws in convenient digital download format.
From the February 2013 issue #202
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