Common edge profiles
An edge profile is the shape routed along the edge of a board. A few are used again and again:
- Roundover: softens a sharp corner into a quarter circle. It is comfortable to touch and helps finishes cover the edge, because sharp corners tend to wear through.
- Chamfer: removes the corner at an angle, giving a flat bevel.
- Cove: cuts a concave curve into the edge.
- Ogee and classical profiles: combine curves for decorative edges on tabletops and moldings.
- Rabbet: removes a step along the edge, often for joinery or for setting in a back panel.
Smaller sizes make subtle changes, while larger ones make more dramatic shapes but remove more wood. Many of these shapes are made by router bit profiles of different sizes, so it helps to check the radius or angle on the bit’s packaging and to test on scrap.
How bearing guided bits work
Many edge bits have a small ball bearing at the tip or the base of the cutter. The bearing is the same diameter as the part of the bit that sets the cutting depth. When the bearing rides against the edge of the board (or a template), the bit cuts to a fixed depth from that edge. That is why these bits are so well suited to edge work: the router itself does not need a fence, and the profile follows the board’s shape, including curves.
A few practical points:
- The bearing rolls only if it is clean and spins freely. Dust and pitch can cause it to stick and leave marks on the wood.
- The bearing needs an edge to ride against. If the edge is rough, wavy or has been sanded unevenly, the routed profile will copy those flaws. Smooth the edge first.
- Bearings wear out. If one feels rough or wobbles, replace it.
- Set the cutter height carefully. On a roundover, a tiny change moves the line where the curve meets the face.
When the cut is wider than a single pass can remove comfortably, take it in steps, and lower the bit or change to a larger bearing between passes where the bit allows it.
Test on scrap first
Use an offcut of the same species and thickness. Cut a short length, then look at the profile and measure it against what you want. Adjust the height in small increments. It is much easier to set the cutter on scrap than to repair a gouged edge on a finished top. The same scrap can be used to check feed speed.
Feed direction on edges
For a handheld router, work counterclockwise around the outside of a workpiece, so that the bit’s rotation pulls the router gently toward the edge instead of away from it. A stable base on the face of the board is essential, and a clamped board beside a narrow edge helps keep the base level. On a router table, the work is fed against the rotation, from right to left, with the fence or a starter pin supporting the board. If you do a lot of this work, understanding what to look for in router table features can make the job safer and more repeatable.
Preventing burn marks
Burning is dark scorching along the cut. It is caused by heat, and heat usually comes from friction. The usual causes are:
- A dull or dirty bit. Resin builds up on the carbide and makes friction. Cleaning the bit often solves the problem.
- Feeding too slowly or pausing. If the bit rubs without removing material, the wood scorches. Keep a steady pace and avoid stopping in the cut.
- Speed set too high for a large bit. Reducing tool RPM, as the bit’s guidance suggests, may help.
- Taking too deep a cut in one go, so the bit labors.
- Dense or resinous wood. Species like cherry and maple are known for burning more readily than softer woods, so slower speed and lighter passes are especially helpful there.
If a faint burn remains, a few light strokes with sandpaper often remove it, but heavy burning on a profile is harder to fix without losing the shape.
Preventing tear-out
Tear-out happens when the bit lifts fibers instead of slicing them. It tends to appear where the grain changes direction or where the bit exits the board. To reduce it:
- Do the end grain first. Rout the short ends of a board before the long edges. The later long-grain pass removes any small breakout at the corners.
- Take light passes. A shallow final pass is gentler on the surface.
- Use sharp bits. A dull edge crushes and tears instead of cutting.
- Back up the exit. A scrap block clamped at the end of the cut supports the fibers.
- Think about the grain. Where the grain runs uphill toward the bit, tear-out is more likely; sometimes a different direction of approach, or a tiny climb-cut first pass on a long edge by a very experienced user, is used. A beginner will usually be better off just taking lighter cuts. Differences between hardwood versus softwood matter here, as some woods with interlocked or wild grain are more prone to tearing.
Finish the edge
After routing, a light sanding with fine paper takes off the faint ridges that any cutter leaves. Sand with the shape, not against it, and avoid flattening the crisp lines of a profile. Wipe dust away before finishing, since dust left in the profile can show up under a clear coat.
Safety reminders
Wear eye and hearing protection and a dust mask. Unplug the router before changing the bit or depth. Keep your hands away from the cutter, never reach across a spinning bit, and let it stop completely before setting the router down.