Perfect Grooves and Dadoes on Router Table
When routing a deep groove (or dado) on the router table, you’ll get much smoother results by making a couple of shallow cuts. To do this in the conventional way, you simply raise the height of the bit between cuts. But here there’s a catch. Adjusting the bit height often shifts its position enough to create a “stepped” cut (photo at right). So you end up trading a clean cut for an inaccurate groove..
But all is not lost. There’s a simple trick you can use to get both a clean and accurate cut. The key is to avoid having to change the bit height between cuts. To do this, I set the bit to full height and then install a spacer over it, as shown in Figure 1. The 1/4″ hardboard spacer is held in place with a cleat at each end and can be be added or removed in a snap.
You make the first, shallow cut using the spacer, then slip it off for the second, full-depth cut. And the bonus is that you actually get the job done quicker.
