If you’ve ever built a wooden box you know that it is virtually impossible to get the four sides to align perfectly along the top, even if you have executed your joinery flawlessly. It is quite common that you will end up with small ridges in each corner where the pieces meet, and if you don’t address it, the box will look as though it is poorly constructed. There are several ways to deal with this (hand plane, cutting on a table saw, power sander, etc.), each introducing challenge and risk into the equation. The infamous craftsman Jimmy Diresta shares a technique that he has come up with to deal with this challenge. The steps are straightforward, and the results are positive and consistent.
Make a sanding sled. Using some scrap material, attach a piece of sandpaper that will be used to flush the joints.
Mark the edges of the box. An important part of this process is to keep track of where you have removed material, and which portions of the wooden box top remain untouched by sandpaper. Use a pencil to mark a line on each surface. A double line is appropriate so that you are sure to notice any remaining lines after sanding.
Work the sled across the wooden box top. Use careful, deliberate motion to remove wood from the high spots of the wooden box top. You’ll have to be patient and let the sandpaper do the work. It feels like a slow process but it will be over before you know it. Keep going until all of the pencil lines are removed. Check your work by feeling the joints, but avoid looking at it because appearances can be deceiving.
This technique for flushing a wooden box top provides a helpful approach to achieving a perfectly flat top on your next box project.