Router: Hinge Recessing, Worktop Joining, and Edge Profiling

You've ordered a kitchen worktop. It costs £350. The corner join needs to be cut and bolted together before the fitter installs it. You hire someone who says they'll need a router. You ask what router. They say any router will do. They show up with a 1/4" machine, start cutting, the bit whips at full depth through 40mm of laminate chipboard, and the joint comes out rough, off-square, and unbolted properly. The worktop is scrap.

That scenario is preventable. The router is one of the most capable tools in a kitchen extension build, but it's the one most often bought wrong, set up wrong, and used wrong. Getting it right means understanding which machine you actually need, which bits, and the three or four techniques that separate a clean result from an expensive mistake.

What it is and when you need one

A router is a handheld power tool with a collet (a precision chuck) that accepts cylindrical-shanked cutting bits. The motor spins the bit at between 8,000 and 30,000 rpm depending on the bit diameter and the speed setting. You move the router across the workpiece and the spinning bit cuts a profile: a groove, a rebate (a step-shaped recess cut along an edge), a housing (a groove that accepts another piece of timber), or a decorative shape along an edge.

The key difference between a router and a drill is that a router cuts laterally through material as well as plunging into it. The bit doesn't just bore a hole; it removes material across the face of the work as the tool moves. This makes a router uniquely capable of controlled profile cutting that no other handheld tool can do.

For an extension or renovation project, you'll use a router in three main situations:

Hinge recessing is the most common router job in any extension. Butt hinges must sit flush in a recess (a mortise) cut to the exact depth of the hinge leaf, so the door closes properly against the frame. A router with a jig does this in under two minutes per hinge, to a consistent depth. The alternative is a chisel and mallet: slower, harder to keep level, and error-prone on hardwood frames.

Worktop joining is where the router's power rating actually matters. Cutting the bolt recesses that lock adjacent worktop sections together requires cutting through 40mm of abrasive laminate chipboard at a consistent depth. Get the collet size or power rating wrong here and you're either replacing the bit mid-cut or risking a thrown workpiece.

Edge profiling uses a bearing-guided bit that follows the workpiece edge automatically, producing a clean profile in a single pass. This covers chamfers on timber shelves, roundovers on windowsills and door stops, and rebates for draught-strip housing.

Cable channels in timber (routing a slot for cables where chasing masonry isn't possible) are a fourth use, less common but practical in timber-framed partitions where an electrician needs to run cable without damaging structural fibres with an SDS drill.

Fixed base or plunge router

This is the first decision and it affects everything downstream.

A fixed base router holds the bit at a set depth. You set the cutting depth before you switch on, plunge the spinning bit into the work from above, and move laterally. For edge profiling with a bearing-guided bit and for router table work, the fixed base is precise. For any job requiring a controlled plunge into the surface, it's the wrong tool.

A plunge router has a spring-loaded motor housing that slides vertically on two columns above a base plate. You start the motor with the bit clear of the surface, press down to plunge to a set depth (controlled by a depth stop), lock the plunge, then move laterally to cut. When you finish the cut, you release the lock and the spring pulls the bit back above the surface. This is the correct mechanism for hinge recessing, where you need to start and finish the cut within a fixed template, and for any job where the cut doesn't run off an edge.

For extension work, a plunge router is the right choice as a first machine. It covers hinge recessing and worktop joints. A fixed base router can do edge profiling with bearing-guided bits, but so can a plunge router running in unlocked mode. The plunge machine is the more versatile option for the jobs you'll actually encounter.

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The collet size problem

This is where UK buyers get caught out, and no mainstream buyer's guide explains it clearly enough.

Router collets come in two measurement systems: imperial (1/4 inch and 1/2 inch) and metric (6mm, 8mm). UK routers use both, depending on the manufacturer.

Trend, DeWalt, and most professional-grade routers sold in the UK use imperial collets: 1/4" and 1/2". Bosch's POF series uses 8mm. Some budget routers (including some Titan models) use 8mm as their only collet size.

The trap: 6mm is close to 1/4" (they differ by about 0.7mm), and 8mm is close to 5/16". They look compatible but they are not. Forcing a 6mm shank into a 1/4" collet, or vice versa, prevents the collet from gripping the bit correctly and causes runout (the bit wobbling off-centre at high speed). At 20,000 rpm, runout means a rough, inaccurate cut at best and a thrown bit at worst.

Before buying any router bits, check your router's collet specification. It will be stamped on the collet itself or listed in the manual. If you have a Bosch POF 1200 AE or POF 1400 ACE, you have 6mm and 8mm collets. You need 8mm shank bits. If you have a Trend T4EK, you have a 1/4" collet. You need 1/4" shank bits.

The reason this matters for extension work: the most capable and widely available router bits for worktop joints come in 1/2" shank only. If your router doesn't have a 1/2" collet, you cannot use them. Budget routers with 8mm-only collets are a dead end for serious worktop work.

One more detail on fitting bits correctly: always insert the shank fully into the collet, then pull it back 2 to 3mm before tightening. Inserting the bit all the way to the bottom of the collet prevents the collet from closing properly around the shank and creates the same insecure grip as a size mismatch.

Router bit types

The number of bit profiles available is overwhelming. For extension work, you need fewer than ten types to cover everything you'll encounter.

Bearing-guided bits are the ones with a small ball-bearing mounted on the shank above or below the cutting edges. The bearing rolls against the edge of the workpiece or template, acting as a self-guiding reference. No fence or guide rail is needed. The bearing dictates the cut width. Swap the bearing for a smaller one and you change the amount of material removed. This is the basis of all rebating and profiling work.

TCT (Tungsten Carbide Tipped) bits are mandatory for cutting laminate worktops. Laminate and the abrasive chipboard core beneath it destroy high-speed steel bits within one cut. TCT edges hold up through multiple joints. Don't buy HSS bits for worktop work.

Trend is the dominant UK manufacturer for router cutters. Their bits are stocked at Screwfix and Toolstation and the quality is consistent. A starter set of 8 to 10 Trend bits covers 90% of the work you'll encounter on an extension.

Buy the 1/2" set if your router has a 1/2" collet. The heavier shank is noticeably more stable on deep cuts and reduces vibration.

Speed settings

Most budget and mid-range routers run at a fixed speed of around 25,000 to 30,000 rpm. Variable-speed models let you dial down for large-diameter bits. This matters more than most beginners realise.

The rule is simple: larger diameter bits require lower speed. A small straight bit (12mm diameter) cuts safely at 24,000 rpm. A large panel-raising bit (75mm diameter) must run at no more than 12,000 rpm, because the tip speed (the actual speed of the cutting edge through the material) scales with radius, not rotational speed. A large bit running at full speed develops a tip speed that causes the bit to heat rapidly, blunt quickly, and in extreme cases can cause bit failure.

For extension work with standard straight and roundover bits (under 25mm diameter), a fixed-speed router is fine. If you're cutting large-diameter profiles (cove bits over 40mm, panel-raising bits), variable speed matters. The Trend T4EK and Bosch POF 1400 ACE both have variable speed. The DeWalt D26204K runs 16,000 to 27,000 rpm with variable dial.

Hinge recessing: the complete technique

This is the most common router job you'll encounter on any build involving doors, and the one most often described poorly in general guides.

Butt hinges (the traditional rectangular hinges on most internal doors and external door frames) must be recessed so the hinge leaf sits flush with the timber surface. Too deep and the door stands off the frame; too shallow and the door won't close against the stop. The required recess depth is exactly the thickness of one hinge leaf, typically 2 to 2.5mm on a standard domestic hinge.

The professional method uses a hinge template jig:

Trend Butt Hinge Template is the standard UK option and covers 75mm and 100mm hinges (the two sizes used on virtually all domestic doors). It costs ~£60 and requires a 30mm guide bush fitted into the router base, paired with a 12mm straight cutter.

The guide bush is a metal collar that fits into the base plate of the router. The outer diameter of the bush slides inside the template opening, so the cutter follows the template edge precisely. The critical point: the guide bush size must match the jig specification exactly. The Trend Butt Hinge Template requires a 30mm OD guide bush. A different size bush creates a dimensional offset that makes the recess too large or too small.

Using the jig:

1. Position the template on the door stile (the vertical edge of the door) at the hinge location. The template has metal stops that reference against the door edge.
2. Clamp the template firmly. It must not move during routing. Two clamps minimum.
3. Set the router depth to the hinge leaf thickness. Use the actual hinge leaf as a feeler gauge: place the hinge on the door face, hold the router sole alongside it, and set the depth stop so the bit descends exactly to the hinge leaf surface.
4. Fit the guide bush and 12mm straight cutter. Check the bit is inserted correctly (shank pulled back 2 to 3mm from collet base).
5. Switch on the router, allow it to reach speed, lower into the template opening, and rout clockwise around the inside of the template. Moving anti-clockwise (climb cutting) causes the router to pull toward the template rather than push against it, creating an uncontrolled line.
6. The routed recess will have rounded inner corners because the cutter is round. Square these with a sharp chisel. Two light taps per corner.

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For concealed cabinet hinges (the 35mm cup hinges used on virtually all kitchen cabinet doors), the Trend Concealed Cabinet Hinge Jig costs ~£36 and cuts the cup recess to the correct depth and diameter in a single plunge. No guide bush required; the jig centres itself over the mark. This is the right tool for fitting kitchen doors once the carcasses are in.

Without a jig: set the router depth to the hinge leaf thickness, draw around the hinge leaf with a sharp pencil, and rout freehand within the line. This works but requires steady hands and leaves the corners needing more chisel work. The jig is worth the cost for more than four or five hinges.

Worktop joining: what can go wrong and why

Kitchen worktop joins are the highest-stakes router job a homeowner will attempt. The worktop costs between £50 (basic laminate) and £500+ (granite-effect or solid timber), the cut is one-shot, and getting it wrong means replacing the worktop. This is where the collet-size and power-rating decisions made at purchase come back to matter.

The join requires two operations: cutting the butt joint faces flat and square (usually done with a jigsaw or circular saw, not the router), and routing the bolt recesses that pull the two sections together from underneath.

Bolt recesses are shallow channels on the underside of the worktop, perpendicular to the joint line, into which Zip bolts (also called worktop connectors) are inserted. The router cuts a channel about 15mm wide, 10mm deep, at a right angle to the joint. A worktop jig holds the router and ensures the channel is positioned correctly relative to the joint face.

Router requirement for worktop work: you need a 1/2" collet router rated at 1400W or above. The long, large-diameter TCT worktop cutter bits required for cutting through 40mm of laminate chipboard need the stability of a 1/2" shank and the power of a 1400W motor to cut cleanly without stalling or chattering. A 1/4" router for this job risks stalling, bit whip, and a rough cut. The forum consensus across eleven threads is consistent: if you only have a 1/4" machine, use a jigsaw to remove most of the material first and use the router for final cleanup passes only.

Worktop jig options:

Mistakes that ruin worktops:

Jig slip accounts for more ruined worktops than any other error. The jig must be clamped with at least two clamps bearing against a solid reference. Never rely on the jig's own locating pins to hold position. If the jig moves mid-cut, the channel is off-position and the bolt won't pull the joint faces together.

Wrong guide bush size creates a dimensional offset that compounds across the joint. The jig specification will list the required guide bush OD. Trend KWJ jigs typically require a 30mm guide bush. Verify this against your specific jig before cutting.

Blunt bits are a specific risk with laminate worktops. A TCT worktop cutter can go dull after four or five joints in hard laminate, and visibly so after that. A dull bit overheats, burns the laminate surface, and produces a rough edge that won't close cleanly. Buy two cutters per project if in doubt, or use a jigsaw to remove most of the waste first (preserving bit sharpness for the finish cut).

Measurement errors are the most expensive. Bolt channel position is measured from the front edge of the worktop, not from the back. A reversed measurement produces a channel too close to the front face, which may break through. Measure twice, from the front edge, before clamping the jig.

Routing direction and depth of cut

Two technique rules that prevent most beginner errors.

Conventional cut vs climb cut: When routing an edge with a bearing-guided bit, always move the router so the bit rotation is pushing against the workpiece, not pulling the router into it. On a standard router moving left-to-right past a straight edge, with the bit rotating clockwise (viewed from above), the correct direction of travel is left to right on the near edge, right to left on the far edge. The incorrect direction is called climb cutting. A climb cut is when the bit rotation pulls the router forward faster than you're controlling it. It creates a sudden jerky movement and a rough, torn edge.

For internal routing within a template (hinge jigs, worktop jigs), rout clockwise around the inside of the template. This keeps the cutting force directed away from the template edge and produces a consistent cut.

Depth of cut per pass: Never attempt to cut to full depth in a single pass with a straight bit. Multiple shallow passes produce a cleaner edge and prevent the bit from deflecting (bending slightly under load) which causes a bowed cut. For a hinge recess 2.5mm deep, two passes of 1.2mm each. For a worktop bolt channel 10mm deep, three or four passes of 2.5mm each. The Trend guidance on rebates confirms this: cut in a series of steps to full depth, never in one pass.

Dust and MDF

Routers produce fine airborne dust, and the finer the dust, the deeper it penetrates the respiratory system. Softwood dust has a Workplace Exposure Limit (WEL) of 5 mg/m³ under COSHH Regulations 2002. Hardwood dust WEL is 3 mg/m³. Both are inhalation hazards.

MDF is worse. Routing MDF releases both fine particulate and formaldehyde from the resin binders in the board. The dust from MDF routing is finer than sawing or sanding, and the formaldehyde adds a chemical irritant to the mechanical hazard. Kitchen cabinet carcasses are typically MDF or MFC (melamine-faced chipboard), and routing them for hinge cup holes is a routine task.

The minimum PPE for router use is an FFP3 mask (not FFP2, not a basic dust mask). FFP3 provides an Assigned Protection Factor (APF) of 20, which the HSE specifies as the minimum for woodworking machines. For MDF routing, ventilate the work area and connect dust extraction to the router if it has an extraction port.

A dust bag or shop vac connection at the router reduces airborne fine dust significantly. Not all routers have a direct extraction port, but aftermarket extraction attachments are available for most base plate configurations.

What to buy

One important nuance on the Trend T4EK: it's excellent for hinge recessing and light edge profiling, but UK Workshop forum members report heat build-up during sustained use (multiple hinge recesses in a single session). The 850W motor has a lower thermal tolerance than the larger Bosch or DeWalt mid-range machines. For a door's worth of hinges, it's fine. For a full internal door schedule of ten or twelve doors, the T4EK may need cooling breaks.

If you're planning to do worktop joints, buy a 1/2" router and add the T4EK as a second lightweight machine for hinge work if budget allows. Running worktop joints through a 1/4" router is a decision you'll regret once the bit starts chattering at depth.

Alternatives

For hinge recessing only, a sharp chisel is a complete alternative and produces excellent results with practice. The technique is to mark the hinge leaf outline with a marking knife, make a series of shallow chisel cuts across the grain inside the marked area, then pare out the waste to depth. A good carpenter can match a router for accuracy on a single hinge. For a dozen hinges, the router wins on time.

A jigsaw handles worktop cutouts (sink and hob) more practically than a router for most homeowners. The router's advantage is edge quality on the profiled joint faces; the jigsaw's advantage is speed and simplicity for internal cutouts where a plunge cut is required.

Where you'll need this

Routers appear across multiple phases of any extension or renovation project:

• Kitchen installation - routing hinge cup recesses in cabinet doors; cutting bolt channels for worktop joins; edge-profiling worktop butt joints
• Windows and doors - routing butt hinge recesses in door stiles and frames; rebating door linings
• Flooring - routing housing joints for timber floor battens and engineered board systems
• Second fix electrics - routing cable channels in timber stud partitions where chasing masonry is not possible
• Sourcing units and worktops - understanding worktop jointing systems before ordering (butt joints vs mitre, bolt spacing requirements)