It’s a natural fact that wood moves. You can nail it, glue it and reinforce it but you will never stop the wood in your projects from shrinking and swelling with seasonal changes in humidity. So the secret to dealing with wood movement is to work with it, not against it.

More than one woodworker has forgotten how much wood moves when a gaping hole or crack appears in the table that he spent weeks building. Or when a drawer will not open because its front has swelled tight inside the frame. Wood movement can also cause joints to open. Doors that used to swing freely, bind if they don’t have the room to expand.

These things happen because wood was once living with cells that held water vital to its growth. Long after the tree is cut down and the wood is dried, those cells continue to exchange moisture. Under humid conditions during the summer, these cells absorb moisture, swell and cause the piece to expand. As winter approaches and it becomes dry, the wood cells release moisture, shrink and cause the wood to contract in size.

Most wood movement that will affect your work will occur across the width of the piece. That amount will vary depending on whether your boards are flatsawn or quartersawn. The movement along a board's length or thickness is negligible in material that is less than 1 ½ thick.

The following are suggestions on how you can control wood movement in your workshop.

It is important to control the temperature and the humidity in your workshop so that they are close to the environment that the piece will be located in. Basement and garage shops in the east, south and mid America typically require humidity control in the summer and heating n the wintertime.

If possible take delivery of your material at least a week before you start working with it. This gives it time to acclimate to your shop environment.

If it is summer time and the humidity is, high you can assume that the piece is not going to swell much more. In a high humidity condition, you can size the drawers so that they are only about 1/16" smaller than they’re opening. If it is wintertime and it is dry you should move this dimension to 3/16" across the width of the drawer. Because the drawer front will not move along its length, the dimension of 1/16" will be just fine.

If the material is warped, true it up by face or edge joining before you machine. Do not attempt to force the board into flatness with clamps, as the warpage will invariably show up in your finished project.

If the board is twisted or cupped you may lose the majority of the thickness by the time you join one face to flatten it. To reduce this loss try to cut the board into short sections which will reduce the waste. Severely bowed boards require more drastic steps. Cut the board into shorter lengths before joining the edges

Solid wood tabletops can grow as much as a ½" across their width. Attaching a top to the aprons so that it cannot move is asking for a disaster. It's likely the table top will split along the grain or a glue line, or it may bow upwards in the center. Attach the top with shop made wooden clips or steel table clips which we use all the time. The clips hold the top down, and they also move with the wood and slide in the grooves that you saw in the inside face of the table aprons.

When you are involved with carcass work such as a chest of drawers that has web frames attached to solid sides, the web frames cannot restrict the sides from moving. In this situation you can join the frames to the sides with sliding dovetail joints. Stop the dovetail groove about ½" from the front of the sides. To assemble the joint, apply glue to the front 3" or so of the dovetail groove only and this will allow the case to expand and contract as the seasons go by without cracking or splitting.

When building a project like our Roll Top Desk or Computer Center you are dealing with a series of panels that fit inside frames. You need to allow room for the solid wood panels to expand widthwise. Panels won’t expand lengthwise, so fit them tight in that direction. In most instances we apply a little glue at the top and the bottom of the panel usually in the center. This keeps the panel from rattling in the frame.

As the season changes, so will the dimensions of your wood. It’s a rare project that doesn’t require some attention for wood movement. We hope that these suggestions will assist you with your projects.

Shavings & Sawdust.
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