How to Glue a Dovetail Joint

Make clamping blocks. When clamping a dovetail joint, it's essential that you put pressure on the faces of the tails. Otherwise, no matter how tight you clamp it, you may only be putting pressure on the ends of the pins. To ensure that you're clamping the right way, take a block of scrap wood a little longer than your joint is wide and a little wider than the width of the joint and cut notches in it that correspond with the location of the pins. Hold the block over the joint; it should rest only on the faces of the tails. Make enough blocks for each joint.

Dry fit the dovetail joint together to test the fit. This is the time to check for any cracks in the wood caused by too tight a fit between the tails and pins of the dovetail joint. If necessary, take the joint apart and use a chisel to fine tune the fit. Once you have everything exactly the way you want it, reassemble the dovetail joint or joints and check one last time, using clamps and clamping blocks. Use enough clamps per joint to close up all cracks and gaps. If you're making furniture in the shape of a box or rectangle, measure diagonally across the piece to check if the assembly is square.

Squeeze a small puddle of glue onto a flat surface, and get a small glue brush. For small dovetail joints, like those in a drawer, disassemble the joint to apply the glue. Just make sure the pieces are marked for quick and easy reassembly. For larger, carcase dovetail joints, leave the pieces together, but pull the dovetail joints apart halfway.

Apply the glue. Using the glue brush, apply a liberal coat of glue to the inside faces of the tails, the sides of the tails, the inside ends of the pins and the sides of the pins that will mate with the tails. For larger, partially assembled dovetail joints, apply glue to as much of the joint as you can. Keep several damp rags on hand to wipe up the excess glue.

Reassemble the dovetail joint or joints and apply the clamping blocks and clamps. For partially assembled joints, simply use a mallet to drive the joints home, then clamp. Glue will mostly likely squeeze out which is messy but preferable to no squeeze-out. No squeeze-out indicates that you didn't use enough glue. A good rule of thumb is to use just enough glue to get a fine line of glue squeezing out from every surface of the joint once the joint is assembled and clamped. If gluing a box or rectangle, measure diagonally across the piece to check for square, just like you did during the dry run. Adjust if necessary.

Clean up the excess glue. If there's only a little bit, wait about five or ten minutes until the glue sets up on the surface, then use a chisel to carefully lift the glue from the wood. This will minimize how much glue soaks into the wood, which will help when you're finishing the surface of the furniture. However, if the glue is puddled on the surface, you'll have to get it off. Wipe it with a damp rag. Once the glue dries and the clamps come off you'll be able to remove most of the glue-soaked wood by hand planing the dovetail joint.