Edge V-Groove Bits

Edge V-Groove Bits

With the exception of perhaps Baltic birch plywood, no other mass-produced plywood (or other composite sheet material for that matter) looks good with exposed edges. Those mismatched plys, little voids and blemishes are distracting. So, we typically try to hide the edges of plywood as elegantly and seamlessly as possible.

Cutting wood to use as end edging
Rip strips of solid wood for shelf edging that are initially at least 1-1/2″ or wider, for safety. Narrower material will be harder to control accurately during routing and places your hands too close to the cutters.

The usual choice for that task is wood veneer edge tape with a pre-applied adhesive backing. When the veneer species of the tape matches the face veneer of the plywood well, it’s thin enough to hide the edge plys without also looking “applied,” and it makes for a convincing bluff . But the thinness of the veneer and the limited strength of the adhesive often causes the veneer to eventually peel off on its own or become easily damaged through normal wear and tear of the exposed edge. The other option is to glue thicker 1/8″ or 1/4″ strips of solid wood, often called banding, to the plywood edge instead. This adds more abrasion resistance and durability, but the wood must be glued and clamped carefully so it aligns with the faces of the plywood. Or it can be applied overly wide, then trimmed flush afterward. The success of edge banding depends on careful clamping. Any gaps between the plywood and the banding looks amateurish and slapdash.

Setting up cut with v-groove router bit
Install the concave V-groove bit in a router table, and adjust its height until both angled edges of the bit are able to touch the solid-wood edging stock at the same time. This ensures the bit is centered on the stock.

Edge V-groove bits, such as those shown here from Rockler, can give you a leg up on both of the other edge-covering options. The “convex” bit cuts a V-shaped recess into the edge of the plywood that intersects with the top and bottom face veneers of the sheet.

A mating “concave” bit reshapes the edge of solid lumber into a protruding beveled point that fits into the plywood recess.

Checking v-groove router bit height in table
Adjust the router table fence so the rim of the bit’s pilot bearing is flush with the fence facings. Lock down the fence. Then close up the fence facings to minimize gaps on either side of the bit.

Alternately, you could use the convex bit to mill a recess into the solid lumber and the concave bit to reshape the plywood into the beveled point, as shown in the inset photo example, above. This is a less common approach.

V-Groove Advantages

Guiding hardwood edging cut on convex router bit
Rout the convex profile into one edge of the solid-wood edging material with the router set to moderate/high speed. Use a featherboard, if possible, to keep the workpiece pressed firmly against the fence.

This routed intersection of plywood and solid wood has a number of advantages. For one, the recess and beveled point are self-aligning. Unlike conventional shop-made edge banding, which must be clamped at close intervals along the joint to ensure that the banding stays on track, solid-wood connections made with these bits require far fewer clamps. The banding has no way to slip out of registration with the plywood — it needs only to be pressed into place.

Installing convex groove bit in router table
Now replace the concave bit with the convex bit in the router table, and align the fence so the rim of the bit’s pilot bearing is flush with the fence facings. Lock the fence in place.

Another benefit to the “V” configuration is that it contributes more surface area for glue. Plywood typically consists of built-up layers of thick veneer laid crossways. So, on any given edge of a sheet, the pattern will be long/edge grain for one layer, short/end grain the next. The end grain layers can soak up a lot of glue. So, the more surface area the edge joint provides, the stronger the connection of the banding to the core material will be. A V-shaped edge offers a larger gluing area than a flat edge will.

A third asset of this router bit solution is that you have a number of options for how the final edge treatment looks. If you study the three banding options shown in the opening photo, the top example illustrates the solid-wood edge trimmed flush to the face veneers. If you were unable to see the joint from the side, it would be hard to tell that the plywood isn’t actually solid lumber; the banding need not add any protrusion past the plywood’s top and bottom faces if you don’t want it to.

Marking plywood edge for cutting v-groove
Draw a centered reference mark on the edge of the plywood using a sharp pencil point or a fine-leaded mechanical pencil. Check for centeredness by referencing off of both faces of the plywood with the end of a square.

The center example in the opening photo shows the solid-wood edging trimmed to within 1/4″ of the plywood. This way, it looks similar to the effect of applying 1/4″ edge banding to the plywood but with the added benefit of a much thicker core and the self-aligning V-groove.

Or, perhaps you want to have the edging of a plywood shelf make a bolder statement. Easily done: just choose a wood species that contrasts with the plywood veneer for a more dramatic effect, and make the edge banding from that instead. The wider and stronger the color or pattern, the more the custom edging will call attention to itself.

Router Table Use

Adjusting height of convex v-groove bit
Raise or lower the convex bit as needed until the tip of the cutter aligns precisely with the layout mark you made on the plywood. Be sure the bottom face of the plywood is pressed firmly down against the router table.

Many router bits can be used safely either in a handheld router or in a router table. However, these edge V-groove bits require their pilot bearings registered in line with a fence or allowed to follow the edge of a template.

Using multiple featherboards to guide edge router cut
Install a pair of featherboards on the router table fence, if possible, to keep the plywood from lifting up during routing. Then mill its edge in one smooth, steady pass with the router set to moderate/high speed.

If you’re using the bit set to create banding for flat shelving, install them in a router table equipped with a fence and a mid- to full-size router. The edges/ends of a plywood shelf will have plenty of bearing surface on either side of the bit during routing. Align the rim of the pilot bearings carefully so they’re flush with the fence facings. That way, when the bits remove all but a pair of thin corners or a centered knife edge of the plywood or solid wood, the fence will still adequately support the material on the outfeed side of the cut.

Gluing edging to panel with panel clamp
Glue and clamp the solid-wood edging piece in place on the plywood. Rockler’s Mini Deluxe Panel clamps, shown here, make that easy. Then trim off as much excess edging as you prefer to complete the installation.

The only other finesse these bits require during setup is that the center points of their cutting profiles be centered on the material being routed. But it’s not difficult if you use the photos as guides.

Once you experience the benefits of edge V-groove bits, rolls of flimsy edge tape will likely be a thing of the past.

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