Pattern routing is a precise and efficient method of creating multiple copies of a single contoured shape. The concept is easy to understand and the technique simple to execute: Once a template of the desired pattern is shaped and fastened to the workpiece, the router is guided by the cutout shape to replicate the design on the workpiece.

The two main ways of pat­tern routing are described start­ing on page 62. If you are using non-pUoted bits, you need to fasten a template guide to your router’s base plate and make your template slightly larger than the finished size. This compensates for the difference in diameters between the bit and the template guide. If you use piloted bits, on the other hand, a template guide is not used and the template can be exactly the same size as your finished piece.

Pattern routing has countless practical and decorative appli­cations for woodworking, including the use of complemen­tary templates. This method allows you to make templates with curved edges that are complementary images of each other, and then reproduce the patterns on two workpieces.

As shown on page 63, pattern routing can be done just as eas­ily on a router table as with a hand-held router.

Another potentially com­plex task that is simplified by pattern routing is cutting recesses for inlays (page 67) and mortises for door hinges (page 71). Using a template based on the size of the inlay or the hinge ensures that the recess will be precisely the right size.

If you are doing a lot of pat­tern routing you should con­sider buying a pin router. The inverted pin router shown on page 72 features a pin suspend­ed over the table directly above the bit. The stock is guided along the pin, making the tool ideal for doing template work.

Although woodworkers have traditionally used fasteners to attach templates to workpieces in pattern routing—everything from double-sided tape and damps to nails and screws—vac­uum clamping offers several advantages over these methods. As shown on page 78, this clamping system is as strong as dou­ble-sided tape and easier to disengage, and unlike nails and screws, there is no risk of marring the workpiece or striking a metal fastener with the bit.

With its guide mechanism suspended above the work table, a pin router shapes the contours of a hand mirror. The stock is attached below a template of the desired pattern with a vacuum clamping system. The template rides against a guide pin over the table, while the bit, which is mounted directly below the pin, replicates the pattern on the workpiece.