When I first started woodworking it was usually on the weekends because that’s when I had the most time (like most people).  So, when I started a project on a weekend, it might not be until the following weekend before I could work on it again.  Very early on in my quest to be a woodworking Jedi (a path I hope I am still on – but one I don’t really expect to reach) I noticed that if pieces sat for a few days that they would warp.  Naturally, this made me panic every time I started a new project to get everything assembled as quickly as possible.  This, unfortunately, wasn’t very enjoyable.  So, I asked around to find out what other woodworkers do to keep everything flat without freaking out.  What I found out was that with careful milling (assuming your stock is adequately dry), the warping can be significantly reduced and you can assemble more at your leisure.  In practice, this appears to hold water.  What is careful milling?  When planing stock at the planer (thicknesser for those across the pond) one should be careful not to remove too much from one side only.  This has the dramatic effect of reducing warp.  Another thing I do, when it’s appropriate and fitting to the project, is to leave my material as thick as possible.  By not planing to a pre-determined thickness I’ll simply stop when both faces are flat and smooth.  I’ve found that the thicker the board, the less prone it is to warp.  And from a physics stand-point, this makes sense.  One factor that also seems to influence warping, and one that can’t be eliminated by careful milling, is the length of the component.  For example, the longer a rail the more prone it is to warp with prolonged standing – in my experience.

Now I don’t worry about warping like I used to; I can usually prevent it from happening to any significant amount.  I’ve waited as long as two weeks to assemble a large project with no warping troubles.

Relax!  This is supposed to be fun.

**Edit:  Stickering your milled lumber also helps to prevent warping.  I always sticker my lumber after milling (place sticks between boards to allow adequate air exposure on both faces).