Using thin wood wafers called biscuits can strengthen wood joints by providing more glue bonding area. You can use a biscuit joiner (also called a plate joiner) to cut precision mating slots in boards for the biscuits, which are available in three sizes. Or, to save money you can buy a kit to convert either your router or right-angle grinder. The conversion kits will generally cost about half that of a dedicated biscuit joiner.
One way to fix a loose screw in wood is to remove it and then insert toothpicks or burned wooden matches with a coating of wood glue into the hole. Allow the glue to cure, then cut flush and re-drive the screw. You can also insert a plastic wall anchor into the screw hole. When you put the screw back in, it will expand the anchor and will hold solidly.
Do you have any chairs, tables, or other wooden furniture that are a little wobbly due to the glue drying out? Here's how you can tighten things up. First, disassemble the joined pieces. Clean off all of the old glue and dirt with warm vinegar. Rinse with clean water, and let everything dry completely. Use yellow carpenters glue to reassemble all the pieces back together.
Warm vinegar will generally soften the most stubborn old glue on old furniture. Dipping the parts to be reglued in warm water, and then letting them dry out completely, will help to open up the wood pores and allow the new glue to enter the wood more freely. Warming the parts on top of a heater or in the sun will also help open up the pores of the old wood before regluing.
When clamping long or wide panels with bar clamps, a dowel inserted crosswise between the jaws of the bar clamps and the wood will help center the pressure and keep it uniform. Use dowels about as thick as the thickness of the wood you are gluing up.
If you find irregular surfaces at the glue line in wood projects, the problem can be moisture levels. This can happen, for example, when one piece has a 15% moisture content, while those next to it are at 8%. If you glue and plane boards with unequal moisture, those with higher moisture will eventually shrink more than those with less moisture.
Fingerjointing is a process in which short pieces of high grade wood are end glued together to make long lengths of stock. The advantages to this process are cost and availability of long lengths. Fingerjointed wood is used in a variety of applications including interior and exterior trim, moldings, and siding materials. In exterior applications, its one drawback is the way in which the different grains of the various pieces react to weather exposure. The individual pieces may telegraph their differences through the finish coat of paint giving a somewhat uneven or checkerboard appearance over time. Fingerjointing is a wonderful recycler of wood products if you give thought to where it can work best for you.
For a good joint, a fluted or spiraled dowel must fit snugly enough in the hole to allow the glue to come up around it. The dowel should reach to the bottom of the hole and be used with enough glue. For insurance, apply glue to both the sides of the hole and to the dowel itself.
Old bicycle innertubes that are cut into long, narrow strips can make excellent clamps for repairing broken wooden furniture. After gluing a fractured joint, the rubber strips can be tightly stretched around the repair area to hold pieces in place while the glue is drying.
You can extend the the time it takes hot-melt glue to set by slightly pre-warming both the surfaces to be joined with a heat gun. A heat gun also works great for stripping paint and other odd jobs. For example, you can use it to remove bumper stickers, defrost freezers, char-stain wood, dry wood for painting, burn weeds from cracks in sidewalks and patios, light charcoal, loosen rusted bolt nuts and bend certain plastic piping.