8 Essential router bits

Words: Damion Fauser
Photos: Donovan Knowles

Few woodworking tools offer the versatility of the router. Not only can they be used either handheld or secured under the table, but there are also different sizes to choose from, and then you need to pick between plunge and fixed bases. Add to this the sheer variety of bits available and the situation can start to become intimidating for the average woodworker.

Your needs will depend on what you make and this applies particularly when facing the white noise that is router bit selection. I design and make contemporary furniture in solid timber and veneers and work equally between hand held and table-mounted routers. I operate one large, one mid-size and one trim router. I have two router tables, one with a large router and one for a trim router.

For cabinetmaking you may need a selection of raised panel bits and matching rail-and-stile bits for profiled doors, and perhaps also edgebanding bits for applying solid edging to veneered sheet goods. Someone doing period reproductions or restorations may have a large selection of moulding profiles. Similarly builders may have large diameter mortising bits for cutting out hinge gains and framing checkouts. Signwriters will have core box bits and diamond-point bits for lettering.

The type of woodworking you do will inform your router bit buying choices. The router bits shown here are some of the ones I most often reach for. They are shown alongside the profiles they cut, but used in combination the variations are limitless. My advice is to acquire individual bits as you need them for specific projects, rather than buying sets that may have bits you’ll never use. Here are the 8 bits I regard as essential.

1. Straight Bits

These are the workhorses and have surprising versatility. They can be used for grooving, rebating, edge-trimming, templating, mortising, inlay work and more. Commonly available in sizes ranging from 1.5mm to 25.4mm. Recently spiral bits have become more readily available. With their shear-cutting action, they are far superior to the straight- fluted bits as they run cooler, cut cleaner and remove debris more efficiently.

Where possible, I will reach for a spiral bit over a straight-fluted bit every time.
Bear in mind there are up-cut bits, which are great for fast debris removal, such as when cutting deep mortises for mortise and tenon joints. Others are down-cut, very useful for protecting the edges of the cut area from being torn out, such as when template- cutting veneered panels or cutting hinge mortises. Finally, you can get compression bits which have flutes in opposing spirals for both up and down cuts. Needless to say these are the most costly of the bunch but they yield superior results as they bring the best of both – chip removal and edge protection, to the operation.

2. Roundover Bits

These are ideal for profiling and softening hard edges and are commonly available in radii from 2mm up to 25.4mm. I tend to use the smaller ones for the subtle softening of edges.

3. Chamfering Bits

When I want an alternative to a radial profile for softening an edge, I will sometimes reach for a chamfering bit, which leaves a 45° profile on the finished edge. Can also be used to form mitres for box and carcase joints.

4. Rebating Bits

Used for cutting a rectangular cross-section profile from the edge of a board or sheet, these bits have enormous utility in many applications, from small boxes to large-scale kitchen cabinet production. To maximise the versatility of the one cutter, I have a set of bearings of different radii. This allows me to either cut rebates of different sizes or, when I need to cut a big rebate, I can start with a large bearing to take a small bite and then shift down through progressively smaller bearings to take subsequent bites until I reach my final dimension.

5. Templating Bits

I work outside of straight lines on many of my projects. When I need to repeat a curve, or match a one-off profile perfectly,
then a bearing-guided bit is essential. Flush-trim bits have the bearing on the end and were designed for flushing edging applied to panels. Pattern-following bits have the bearing between the shank and the cutting flutes and were designed for following non- rectilinear patterns and templates. Flush-trim bits can be used for both edge-trimming and templating, but pattern-following bits cannot be used for edge-trimming, so if you are working to a budget, a flush-trim bit gives more flexibility.

Basically these are straight bits with a bearing attached, and are also available with either straight or spiral flutes (up/ down or compression). In some templating situations you may be faced with reversing grain direction. Here it pays to have flush-trim and pattern-following bits in your arsenal so you can rout with the best grain direction, and therefore avoid having to switch the template between opposing faces of the workpiece, thereby risking inaccuracies.

An alternative is a double-bearing bit, which has bearings in both locations. This bit allows you to leave the template fixed in place and just flip the whole workpiece over to manage changes in grain direction. Now on the market are also bearing-guided compression bits which leave a remarkable finish in almost any situation.

6. Cove Bits

Used to cut a concave circular profile from the edge of a board, these bits are useful for creating stand-alone edge profiles. When combined with roundovers, chamfers and straight bits, any number of combination mouldings can be achieved. As with roundovers, these are commonly available in various sizes.

7. Dovetail Bits

Used for cutting sliding dovetail profiles, dovetail bits are available in different sizes and with different angles, with the most common being 14°. Visually more appealing, the sliding dovetail is also more structurally sound than a straight dado joint as the tail is less prone to rotating in the socket when under load, for example when a shelf is heavily laden and sags. One weakness of these bits is the narrow neck and therefore it is advisable to remove as much waste as possible from the socket with a straight bit prior to cutting the dovetail profile.

8. Slot Cutters

Slot cutters are another versatile family of bits. Whilst the same result can be achieved with a straight bit, the advantage of using a slot cutter is that the significantly larger radius of a slot cutter and the raking cutting action means debris removal is more effective and therefore the bit runs far cooler. Because these bits are generally operated at a slower speed, they are less prone to vibration and therefore give a cleaner cut. A more cost effective option to buying individually sized bits is to buy one primary shaft/arbor and then invest in cutters of different cutting thicknesses, and bearings of different diameter. Slot cutters are also useful for creating tongue and groove profiles.

In the second part of this feature we’ll look at other factors to take into account prior to purchasing.

Damion Fauser is a furniture designer/maker and woodwork teacher who lives in Brisbane.