Making a large-diameter hole is a job for a drill press, right? All you need are an assortment of hole saws, a set of expensive Forstner bits, and perhaps a wing cutter. But this approach has limitations. For example, you may not have the right size bit. Or it may be impossible to get the workpiece on the drill press. When the hole you need to make falls outside that range, or can’t be done with a drill press, you need another solution. To get the job done, I turn to my router. With a router, some common bits, and a few simple techniques, you can create smooth, large diameter through holes with ease.
For making large or custom-sized openings. I make a simple circle-cutting jig. It's nothing more than an auxiliary baseplate that attaches to your router with double-sided tape. A brad serves as a pivot pin. I install a 1⁄2"-dia. straight bit in the router to do the cutting. The distance between the pin and the outside edge of the bit should match the desired radius of the hole. Make a few test cuts to dial in the set up. Here’s the catch — I don’t use the jig to make the entire hole. After drilling a pivot hole at the centerpoint, you can rout a 1⁄4"- deep circular groove.
To turn the groove into a hole, cut away the waste with a jig saw. The groove serves as a track to help you guide the saw.
Cleaning up the hole is simply a matter of installing a pattern bit in the router and trimming the edge clean.
