14 Fuss-free router-bit setup

When routing certain edge profiles on your router table, such as the door lip shown, the bit removes enough stock that the profiled edge no longer bears against the outfeed fence. In these cases, shim the outfeed fence-we attached ¹⁄₃₂ "—thick plastic laminate with double-faced tape-to provide a bearing surface for the workpiece beyond the bit. Without this, you'll end up cutting a snipe-like gouge when the edge clears the infeed fence.

If a router bit hits the bottom of the collet, you can't tighten it fully, creating the potential for the bit to work loose in use. And with some routers it's difficult to hold the bit at the correct depth while simultaneously tightening the collet nut. To prevent this, slip a snug-fitting O-ring onto the bit shank to hold it in place while you tighten the nut. You could also drop a small rubber grommet into the spindle to prevent bits from bottoming out. When you tighten the nut the rubber will flex as the bit shank draws against it. (You'll find O-rings and grommets at most hardware stores.)

Flush trimming solid-wood edging on veneered plywood or MDF is a good job for a trim router because of its small base and low center of gravity. But even if you use a midsize router, set the bearing depth of the flush-trim bit just below the edge to be trimmed. This way, if you accidentally tip the router, you won't cut into the plywood's veneer. And when trimming away edging, rout in a climb-cut direction, right to left in this example, to avoid tearing out grain on the wood edging.

When possible, trim away excess material from your workpieces at the tablesaw or bandsaw before routing. Trace the profile of the bit onto your stock to prevent overcutting, as shown. Whether you're routing an edge profile, sliding dovetail, or any other task that removes a good bit of wood, doing this will save you time, wear on your bits and router motor, and a pile of shavings.

For a flawless surface, always leave a tiny amount—¹⁄₆₄ " should do it-for a final routing pass to remove burn or chatter marks. On a router table, before making the cut, apply masking tape to the workpiece edge or router-table fence, as shown (two layers if the tape is ultra-thin). Before the final pass, remove the tape for a whisker-thin shave. For handheld work, adhere two or three business cards to your router's subbase for the majority of the routing, and then remove them prior to the final pass.

Rather than adjust the bit's height as you remove material incrementally, set it to the exact height from the start and use removable shims on the table surface. Stack layers of ¹⁄₄ " hardboard or plywood on the table using double-faced tape, with cutouts around the bit, and then remove one layer after each pass. This proves especially helpful if your router or router lift is fussy to fine-tune because you set it once and lock it in.

Use machined brass setup bars, typically sold in kits from ¹⁄₈ " to ¹⁄₂ " in thickness, to set bit depths with dead-on precision. For example, when using a tongue-and-groove bit set on ³⁄₄ "-thick stock, set the groove cutter ¹⁄₄ " from the subbase or table surface, as shown. Then rout the tongue to fit the groove.

Brass setup bars: part #144932, Woodcraft, woodcraft.com.

After perfecting a setup, especially for mating two-bit setups, such as cope-and-stick bits or tongue-and-groove bits (shown), keep a piece of test stock from each bit to use as gauge blocks for quick setup on future jobs.

When routing through dovetails on a router jig, use your actual workpieces to accurately set the bit's cutting depth. First, tape a piece of scrap onto the face of the workpiece that will mate with the one you'll rout, letting it extend 1" or so from the end of the workpiece. Next, set the router in position on the jig's template with the bit tightened in the collet. Lower the bit until it touches the scrap piece for a dead-on setting. If you prefer to make your tails and pins a little proud to be trimmed after assembly, simply lower the bit another one-eighth turn of the router's depth-adjustment dial, and then lock the router's base.

Anytime you're routing hinge mortises, unfold the hinges and set the router onto one leaf of each. Then lower the bit until it touches the benchtop for the exact cutting depth for those hinges.

The gap between the bit and opening in the router's base sometimes makes it difficult to accurately set a bit's depth by standing a steel rule on end. Instead, use a rule with scales marked vertically on the ends, preferably in ¹⁄₃₂ " increments.

Steel rules: 6" rule, part #13394, 12" rule, part #13404; Hartville Tool, hartvilletool.com.

Many of today's routers come with a centering cone, used to center the subbase to the spindle. An exactly centered bit proves critical for joinery tasks that involve guide bushings, such as dovetails or box joints. Without being centered, your joints will likely not fit perfectly. If your router didn't come with a centering cone, get an aftermarket one.

Router centering cone: part #RA1150, Tool Barn, toolbarn.com.

To position a router-table fence flush with a bit's bearing or a particular point on a bit's profile, get it close by eyeballing it, and then tighten down one end of the fence. Holding a steel rule against both fence faces, pivot the loose end until the rule hits the mark you want. Tighten the other end of the fence when the infeed and outfeed faces line up with your registration point on the bit.

When fine-tuning a bit's height with an above-the-table adjustment tool, such as the one shown here, make a pencil mark on the table and line it up with the scale's zero reference. Now when making fine adjustments up or down you will always know where you began, to avoid overshooting the starting point should you have to back up.