Router Bits: TCT, Shank Sizes, and the Five Profiles That Cover Most Joinery
What a router bit is, why TCT beats HSS for durability, the shank size that matches your router, and the five profiles a homeowner actually uses. Buy from £8 each.
A homeowner buys a router for hinge work, plus the bit that came in the box. Six months later, the worktop arrives, they reach for the same bit, and the kitchen fitter who walks past mentions in passing that it's a 1/4-inch shank, the worktop jig needs a 1/2-inch, and they cannot use this router for that job. The router bit decision feels like an accessory choice. It isn't. Bit shank size, profile type, and bit material decide what jobs you can actually do with the router you bought.
Five profiles cover almost every realistic homeowner joinery job. TCT (tungsten carbide tipped) cutters last fifty times longer than HSS (high-speed steel) at twice the price. The shank size question is whether you bought a 1/4-inch or 1/2-inch router, not a preference. Nailing these three decisions means buying bits once instead of three times.
What a router bit is
A router bit (also called a router cutter) is the consumable cutting tool fitted into a router's collet. The bit spins at 12,000 to 24,000 rpm and removes timber along the path the router follows. Bits come in dozens of profiles, but five cover the vast majority of homeowner joinery work: straight, roundover, rebate, chamfer, and ogee. Each profile has a different geometry and produces a different cut.
The cutting edges are either solid HSS or, more commonly today, brazed-on TCT inserts. The bit body is hardened steel with a shank that fits into the router's collet. Shank diameter is the most important specification: 1/4 inch (6.35mm) and 1/2 inch (12.7mm) are the two UK standards. Some European routers use 6mm and 8mm shanks; Trend, Bosch, Makita, and DeWalt routers in the UK trade range typically take 1/4 and 1/2 inch.
TCT versus HSS: pay double, last fifty times
This is the easy decision and the one beginners often get wrong.
HSS (high-speed steel) cutters are the cheaper option. They sharpen well, take a fine edge, and produce excellent finish on softwood. They also blunt quickly. A single hour of cutting MDF with an HSS straight bit dulls the cutting edge enough that the next cut will burn the timber rather than slice it. HSS bits earn their place on light, occasional use in clean softwoods only. Furniture restorers and bespoke fine joinery sometimes prefer HSS because the edge is sharper than TCT and produces a better finish on figured hardwood.
TCT (tungsten carbide tipped) cutters are the practical default. The cutting edge is a brazed-on insert of tungsten carbide, a material so hard that it will cut MDF, chipboard, plywood, hardwood, softwood, and laminate at production rates without dulling. A TCT cutter will outlast an HSS cutter by a factor of fifty in mixed homeowner use. The trade-off is that TCT cannot be honed to quite the same fine edge, but the durability difference is the deciding factor for almost every realistic use.
For a homeowner extension toolkit, buy TCT. The price difference per bit is around 8 to 12 pounds versus 4 to 6 pounds for HSS, but you'll buy one TCT bit where you'd otherwise buy ten HSS replacements over the same project.
Tip
The exception: if you are routing a single small radius on a piece of finished hardwood furniture and want the absolute cleanest cut, an HSS bit produces a slightly cleaner finish on figured grain. For everything else (worktops, kitchen units, doors, MDF skirting, plywood shelving), TCT is the right material.
Shank size: match the router, not the application
The shank diameter must match the router's collet. A 1/2-inch shank does not fit a 1/4-inch collet, and a 1/4-inch shank held in a 1/2-inch collet will vibrate violently and eject under load.
Most UK homeowner routers (Bosch GOF1250CE, Trend T5EB, Makita RT0700C, DeWalt D26204) are 1/4-inch collet machines. Trade routers (Bosch POF 1400 ACE, Trend T11EK, Festool OF 2200, Makita RP2301FCXK) are 1/2-inch. Some trade routers ship with both 1/4 and 1/2 inch collet inserts so they can take either shank, but the body of the machine is sized around the 1/2-inch standard.
| Router collet | Bit shank to buy | What it can do |
|---|---|---|
| 1/4 inch (6.35mm) | 1/4-inch shank only | Hinge recesses, light decorative profiles, light rebates and chamfers in softwood up to 18mm |
| 1/2 inch (12.7mm) with 1/4-inch insert | Both 1/4 and 1/2 inch | Everything |
| 1/2 inch only | 1/2-inch shank only | Heavy work, worktop jointing, deep rebates, hardwood kitchen units, large profile bits |
For worktop jointing specifically, the bit must be 1/2-inch shank. A 1/4-inch shank does not have the rigidity to take the side load of a deep cut through 38mm of laminated chipboard. The Trend C153 worktop jointing cutter is the trade default; it's a 12.7mm diameter, 50mm cutting length, 1/2-inch shank, two-flute TCT bit. Around 25 to 35 pounds.
For hinge recess work, a 1/4-inch shank is fine because the cut is shallow (3mm) and the cutter is small (12.7mm or smaller). The Trend C153A in 1/4-inch shank is the equivalent for hinge work. Around 10 to 15 pounds.
Warning
Never use an adapter or sleeve to fit a 1/4-inch shank into a 1/2-inch collet, or a 1/2-inch shank into a 1/4-inch collet. The first ejects the bit under load; the second physically does not fit. Adapters of either type are not safe and not standard. Buy the right shank for the router you have.
The five profiles that cover most homeowner joinery
A starter kit of five profiles handles almost every realistic homeowner cut.
| Profile | What it does | Typical use |
|---|---|---|
| Straight cutter | Cuts a square-bottomed groove or rebate; the workhorse profile | Hinge recesses (12.7mm), worktop joints (12.7mm 1/2-inch), shelving dado (19mm), trenching |
| Roundover (1/4-inch radius typical) | Rounds a sharp 90-degree edge to a quarter-circle radius | Softening edges on shelving, table tops, treads, kitchen plinths, painted MDF mouldings |
| Rebate cutter (bearing-guided) | Cuts a stepped rebate along an edge, depth set by bearing | Glass panel rebates in cabinet doors, drawer-bottom housings, edge rebates for inset panels |
| Chamfer (45 degrees typical) | Cuts a 45-degree bevel along an edge | Decorative edges on shelving, picture-frame mouldings, softening sharp arises |
| Ogee | Cuts an S-shaped decorative edge profile | Period-style mouldings on cornice, picture-rail, bookshelf edges, hand-built kitchen door details |
For a homeowner extension toolkit, the straight cutter is mandatory because hinges require it. The roundover is the next-most-useful because softening sharp edges before painting is the single most common decorative cut. The remaining three are application-specific; buy them as you need them.
A starter set bundle with all five profiles in 1/4-inch shank costs around 40 to 60 pounds (Trend SET/SS9 or equivalent). For 1/2-inch shank, equivalent kits run 80 to 120 pounds. Trend, Wealden, Titman, and Whiteside (US import) are the established UK brands.
Bearing-guided versus non-guided
Some bits have a small ball bearing fitted at the end of the cutter, the same diameter as the cutter shoulder. The bearing rolls along the edge of the workpiece while the cutter cuts a profile alongside it. This means you don't need a fence or a jig; the bearing keeps the cutter the right distance from the edge.
Bearing-guided bits are the right choice for any cut that follows the existing edge of a workpiece: roundovers, rebates, chamfers, ogees on furniture, and trim work. The bearing means setup is just clamp the workpiece, set the depth, and rout along the edge. The bit handles the rest.
Non-guided bits (straight cutters, dado cutters, hinge cutters) need a fence on the router base or a guide bush running against a jig. These are the right choice for cuts that don't follow an existing edge: dado housings across the grain, hinge recesses set back from the edge, mortice pockets.
A homeowner toolkit should have one bearing-guided roundover or chamfer (for general edge softening) and one straight cutter (for hinges and dado work). That covers 80% of the realistic use cases with two bits.
Diameter and cutting length
Beyond profile and shank, the two specifications that matter are the cutter diameter (which affects cut width and inside corner radius) and the cutting length (which affects how deep you can cut in a single pass).
For straight cutters specifically:
| Diameter | Cutting length | Shank | Use |
|---|---|---|---|
| 6.35mm (1/4") | 20mm | 1/4-inch | Light dado cuts, narrow grooves, fine inlay work |
| 12.7mm (1/2") | 12mm | 1/4-inch | Hinge recesses (Trend C153A), shallow rebates |
| 12.7mm (1/2") | 50mm | 1/2-inch | Worktop joints (Trend C153) |
| 19mm (3/4") | 25mm | 1/2-inch | Wide dado housings, deep grooves in solid timber |
| 25mm (1") | 12mm | 1/2-inch | Wide shallow rebates, large-area surface levelling |
Match the cutter to the job. A 6.35mm straight cutter cannot rout a hinge recess in a single pass because most hinge plates are wider than 6mm; you'd need multiple passes and the recess walls would be uneven. A 50mm cutting-length 12.7mm cutter is overkill for hinge work and unwieldy in a 1/4-inch router; reach for the 12mm cutting-length 1/4-inch version instead.
What to buy
For a single-purpose extension toolkit, two starter purchases cover most realistic needs.
| Purchase | Approx price | What it covers |
|---|---|---|
| Trend SET/SS9 nine-piece TCT 1/4-inch shank starter set | £60-80 | Hinge recess, roundover, rebate, chamfer, ogee, plus a few specialist profiles. Standard homeowner kit. |
| Trend C153 12.7mm 1/2-inch shank straight cutter (single) | £25-35 | Worktop jointing. Buy alongside the worktop jig if not already in a hire kit. |
| Wealden T2010 5-piece bearing-guided 1/4-inch starter set | £45-65 | British-made alternative; bearings fitted as standard |
| Trend C153A 12.7mm 1/4-inch shank straight cutter (single) | £10-15 | Hinge recesses with the homeowner-standard 1/4-inch router |
For a recommendation: buy the Trend SET/SS9 starter set if you have a 1/4-inch router and want the full range of profiles. Add a Trend C153 1/2-inch worktop cutter if you've also bought or hired the worktop jig and 1/2-inch router. Total kit around 100 pounds covers every realistic kitchen-extension routing job.
For a buy-British alternative, Wealden Tool Company in Tonbridge manufacture TCT cutters with strong reviews from UK joiners. Lifetime guarantee, sharpening service available. Slightly higher prices than Trend but excellent quality.
Tip
A pack of replacement bearings for bearing-guided bits is a useful consumable. Bearings seize over time, particularly on routers used outdoors or in damp conditions. A pack of five replacement bearings is around 8 pounds from Trend or Wealden and saves replacing whole bits when a bearing fails.
Care and maintenance
Router bits last a long time if treated correctly. Three habits extend bit life:
Clean the cutters after each use. Resin and pitch from softwood builds up on the cutting flutes. A spritz of bit cleaner (Trend Pro Clean or equivalent) and a stiff brush removes the buildup. A clean bit cuts cleaner and runs cooler.
Store bits in their plastic cases or a dedicated rack. Bits rolling around in a toolbox knock the cutting edges against each other and chip the carbide. The plastic boxes that bits ship in are designed for storage; keep them.
Have TCT bits professionally sharpened when they dull rather than replacing. A TCT sharpening service costs 3 to 5 pounds per bit and restores the original cutting performance. Trend and Wealden both offer this; turnaround is usually a week. A bit can be sharpened five or six times before the carbide is worn down too far.
Where you'll use them
Router bits are second-fix and finishing tools:
- Hanging internal doors for hinge recesses (12.7mm 1/4-inch straight)
- Kitchen installation for cabinet door hinge recesses, end-panel rebates, and decorative edge work
- Worktop installation for worktop jointing with a 1/2-inch shank straight cutter and the worktop jig
- Skirting and architrave for custom mouldings and edge profiles where standard machine-run mouldings aren't available
The bits live in the toolkit through second fix. Once decoration is complete, they sit in storage until the next project.
Common mistakes
Wrong shank for the router. Already covered. 1/4-inch shank for 1/4-inch collet, 1/2-inch shank for 1/2-inch collet, no exceptions and no adapters.
HSS bit on hardboard, MDF, or laminate. HSS dulls within minutes on these materials. The cut burns rather than slices. TCT is mandatory for any board materials.
Forcing a dull bit instead of sharpening. A dull bit cuts slower, burns the timber, and makes you push harder. The forces involved are significantly higher than with a sharp bit, and the higher forces increase the chance of the bit grabbing or kicking back. Replace or sharpen at the first sign of burning.
Cutting too deep in a single pass. Most bits should not cut deeper than half their flute length per pass. Take two or three light passes rather than one heavy one. The cut is cleaner, the bit lasts longer, and the router is easier to control.
Ignoring the rotational direction. Routers spin clockwise viewed from above. The router must move into the cut against the rotation, which means moving left-to-right when cutting on the far edge of the workpiece, and right-to-left on the near edge. Reverse the direction and the bit pulls the router off the line; this is called climb cutting and is a recognised hazard for inexperienced users.
Buying a profile bit before knowing the application. A drawer of unused decorative profiles is the second-most-common waste in any homeowner toolbox (after unused saw blades). Buy the bits you need for the project in front of you. Buy the others when the next project demands them.