Adjustable shelf pins are a great way to add some flexibility to the design of a cabinet or bookcase. They let you customize the project to suit your storage needs. Drilling shelf pin holes seems to be about as basic as you can imagine. But if you’ve ever ended up with a shelf that rocked, or was uneven, you know it’s not as simple as it seems.
I use a shop-made jig to drill accurate holes. The jig keeps the bit square to the workpiece and sets the hole spacing. A hardboard cleat along one edge registers the jig along the edge of the workpiece. This allows you to drill holes before or after assembly. To use the jig, you start by marking the location of the center hole for each batch. Then it’s just a matter of aligning the centerline of the jig on the mark and clamping it in place, as you can see in the photo on the opposite page.
Just about any hand drill will work fine for drilling the holes. But I do want to make note of the bit. I use a brad point bit. It makes a clean hole — especially in plywood. And it’s a good idea to use a stop collar to drill to the right depth (about 3⁄8").
The trouble with drilling shelf pin holes is it’s easy to go overboard. You often see this in commercial cabinets. The inside is peppered with lines of holes running from top to bottom. The fact is that most shelf pin holes will never get used, anyway. So drilling long rows of holes ends up being a waste of time. Instead, what I’ve found works best is to drill shelf pin holes in sets of three to five holes. It still gives you plenty of flexibility, but you avoid the Swiss-cheese look. This means you need to carefully plan where to drill the holes. For example, books generally have a few pretty standard sizes. So drilling shelf pin holes less than 6" to 8" from the top or bottom of the case is pointless. It’s better to space the holes in “book-sized” increments (12"-14") to accommodate anything from a shelf full of pint-sized paperbacks to oversized coffee table books.