Aside from a dovetail joint, the box, or finger joint is one of the strongest joints to reinforce a corner. Before the era of corrugated cardboard containers, air filled packaging, and overnight shipping, wooden boxes and shredded wood were used to package fragile goods (think leg lamp in A Christmas Story). An inexpensive way to strengthen smaller boxes so they would survive the trip intact was adding finger joints to the vertical corners.

In this post, I’ll show you how to make a simple box joint jig for the modular crosscut sled.

As I mentioned in part one of the Modular Crosscut Sled series, I built the modular sled to make small boxes. One way to make a box stronger is adding splines to the beveled corners, so this jig is essential for me. The jig is easy to make and uses minimal materials.

There are three tweaks to the sled to make it perform to a suitable standard. First, the runners may need to be trimmed to be sure the sled slides smoothly. Second, the zero clearance insert should be shimmed to fit perfectly. Finally, the rear fence can be adjusted to get it as close to square as possible.

Now that the sled base and fences are complete. the next step is to attach the fences to the base and add the runners. This installment will detail the step by step process to finish up the sled. The final installment will cover fine tuning to improve the sled’s performance.

Now that the design is complete, it’s time to make some man glitter, otherwise known as sawdust. The next two posts will be a step by step guide to building the sled. The first installment reviews building the sled base, and the second covers the remainder of the build.