Q: Can I tighten my wiggly kitchen chairs without taking them apart and re-gluing the joints? - Homer H. Kurth, Alma, MO
A: Unfortunately, there’s no perfect solution to the problem because there are too many types of joints used to make chairs and too many remedies to cover here. But the most common causes of a wiggly chair are failed glue joints and loose or worn tenons. The following procedure works well for repairing many of these cases:
Start by labeling all parts and taking apart loose joints. You will probably have to use spreader clamps or a rubber mallet to “persuade” stubborn joints. Scrape old glue from tenons and mortises. If a tenon fits loosely, enlarge it with a piece of veneer or by making a thin wood shaving with a plane and then gluing the shaving around the tenon (see photo). Reassemble using yellow wood glue on both parts of the joint, and draw the glued joints together with clamps.
Disassembling, cleaning and re-gluing the joint almost always results in the best repair, but if the chair is not used heavily then you can also try the following procedure, which doesn’t require disassembling the joint:
Drill a small perpendicular hole that penetrates the joint. Inject slow-setting epoxy with a glue syringe, wiggling the joint as you inject to distribute the epoxy around the tenon. This fills the gap and is strong enough for structural support. If the hole is visible when the chair is upright, use a wood filler to cover the bore. Finally, stain and apply a finish.
Another option (if the joint is not structural) is to inject a product intended to swell wood and tighten loose joints. - HANDY