Rocking chairs are for rocking, not walking. A rocking chair "walks" when it travels across the floor as it rocks, and this can happen on carpet as well as on a bare wood floor. The main reason for walking is a slight difference between the profiles of the two rockers. The imperfection causes an imbalance that allows the chair to turn the energy of rocking into forward momentum. You can address this problem in one of two ways. You can get out your sander and wood plane and correct the difference between the rockers, or, if you prefer an easier solution, you can cover the rockers with something that will provide enough friction to keep the chair in place.
Five elements govern the comfort of a rocking chair. Four of these‒the angle of the backrest to the seat, the pitch of the seat and backrest, the radius of the runners and the length of the runners ‒ don't affect the propensity of the chair to wander, but the fifth one ‒ the alignment of the runners ‒ does. The runners have to have exactly the same profile, and they must be mounted exactly parallel. If the rockers don't fulfill these conditions, the chair develops a wobble that can turn into forward momentum.
The walking problem may be compounded by loose joints that add to the wobble, and this is particularly true if the loose joints are the ones holding the rockers to the legs. It's fairly simple to glue these joints back together with carpenter's glue. If the chair still walks after you do this, the best way to handle the problem is to plane or sand one of the rockers to match the other one.
Fixing a Walking Rocker
You can fix a rocker in your living room, but you'll probably do a better job if you set the chair upside-down on a workbench and clamp it in place. Re-glue all the joints that need it, particularly those between the rocker and the legs. If one of these is loose, pull the leg clear of the hole in the rocker, clean out the hole, add glue and reinsert the leg, making sure it goes all the way. Once the legs are completely inserted, the rockers should be parallel. Let the glue set, then test the chair, and, if it still walks, follow this procedure.
Step 1 Determine Which Rocker Is Larger
Extend a straightedge on both rockers and run it along them, observing closely to see where it's touching one rocker while missing the other. This will give you an idea which of the rockers is larger than the other.
Step 2 Make a Drawing
Tape a piece of kraft paper to the side of the chair that has the smaller rocker. Align the paper with precisely measured marks on the chair legs so you can put it in the exact same location on the other side of the chair. Draw an accurate profile of the rocker using a pencil.
Step 3 Transfer the Drawing
Tape the paper to the other side of the chair and tape it in place so you can compare the rocker profiles. Note that if the paper was on the outside of the chair when you made the drawing, you'll have to tape it on the inside of the chair to get the rocker profile in the same direction.
Step 4 Sand and Plane the Rocker
Using the drawing as a reference, remove material from the larger rocker with a wood plane or belt sander to get the rocker to match the drawing. Once you're finished removing material, sand the rocker by hand with 120-grit sandpaper to smooth it out.
Step 5 Test the Rocker
Set the rocker on the floor and try it out. If it still walks, sand and plane some more. It may help to update your drawing to improve accuracy.
Do It the Easy Way
Sanding and planing chair rockers may not be your thing, and even if you're game, you may not have the tools you need to do an accurate job. No worries. You can always stop the rocker from walking by adding friction to the runners. For example, you can attach felt strips to the bottoms of the rockers using contact cement. Alternatively, cut strips from a sheet of no-slip shelf liners and glue them to the rockers. These and other materials, such as sueded leather, should provide enough friction to keep the chair in place. Make sure you stretch out the material when gluing it to avoid creases or bubbles that will give you a rough ride when rocking.