Upgrading a TV Unit: Installing Metal Cable Grommets & Premium Furniture Knobs

A TV unit can be upgraded both functionally and visually by retrofitting cable grommets and replacing standard handles with solid furniture knobs.

Introduction: Adapting the TV Unit for Modern Technology

Modern home entertainment systems require structured cable routing. When assembling a standard TV unit, you often find that factory-made cable openings are missing, placed in the wrong spot, or too small. Particularly with compact furniture pieces, such as a sideboard that is 35 cm deep, space for AV receivers, games consoles, and their rigid HDMI cables quickly becomes tight. If cables cannot be routed cleanly downwards or out through the back, equipment cannot be pushed deep enough into the compartment.

Even with wider models, for instance when a lowboard measures 250 cm and holds multiple devices side by side, a chaotic tangle of power and data cables easily forms without deliberate cable management. Retrofitting cable grommets solves this problem permanently. At the same time, such a modification provides the opportunity to visually enhance the furniture. Standard plastic handles supplied with flat-pack units can be replaced with minimal effort using heavy metal furniture knobs, giving the cabinet a completely new level of quality. This guide explains the technical differences between the components and walks you through installation step by step.

Cable Grommets: Types, Shapes, and Materials

Choosing the right outlet depends on the number of cables, the position on the furniture, and your desired design. In principle, these components consist of an outer ring that sits firmly in the cut-out hole, and a removable cover, which is often fitted with a brush seal.

Material Differences

The choice of material determines durability as well as the tactile quality of the component.

• Plastic: Lightweight and practical. Ideal for concealed areas inside the cabinet.
• Metal: A metal cable grommet is typically manufactured from die-cast zinc or steel. It resists warping, will not crack under pressure, and provides a cool, weighty feel. Metal versions are particularly suited to visible surfaces because they can be colour-matched to other hardware.
• Aluminium: An aluminium cable grommet is corrosion-resistant and delivers a matte, technical aesthetic that complements modern Hi-Fi equipment well.

Shapes

The geometry of the cable tidy must match the available tools and the cable volume.

• Round: The round cable grommet is the absolute standard in furniture making. It can be neatly recessed in just a few minutes using a standard hole saw.
• Rectangular: A rectangular cable grommet provides a wider slot and is suitable when numerous thick power leads or wide plug extensions need to be fed through. A jigsaw is required to cut this opening.

Selection Criteria: Finding the Right Dimensions

Before using any tools, the exact dimensions of the required components must be determined. An incorrect diameter means plugs will not pass through or the fitting will wobble inside the hole.

The Right Diameter

The dimension of a round cable grommet always refers to the required cut-out hole, not the outer rim of the cover ring.

• 60 mm: A 60mm desk cable grommet is sufficient for standard cable bundles. HDMI leads, USB cables, and slim two-pin plugs pass through easily.
• 80 mm: When thick mains plugs or bulky laptop power supplies need to be routed through the furniture, an 80mm desk cable grommet is essential. A standard plug has a diameter of roughly 36 mm to 40 mm and can be difficult to manoeuvre through a 60 mm opening when other cables are already present.

Visual Integration

The colour of the fitting should harmonise with the furniture finish or the remaining hardware. For a light cabinet carcass, such as a lowboard in beige or white, a white cable grommet blends seamlessly into the surface. If you want to create a bold contrast or match black furniture legs, a black cable grommet provides a crisp, industrial accent.

Retrofitting Furniture Knobs: Technical Basics

Swapping handles is the fastest method to upgrade a typical TV lowboard that is 140 cm wide and fitted with two or three drop-down flaps. However, several technical parameters must be taken into account.

Threads and Screws

Metal furniture knobs are usually fixed with metric machine screws. The industry standard for this fixing is the M4 thread. Unlike wood screws that bite directly into chipboard, a metric thread requires a complete through-hole drilled through the cabinet front.

Front Thickness and Screw Length

The length of the required M4 screw depends directly on the thickness of the furniture front. The screw must extend fully through the panel and engage sufficiently into the thread of the knob without bottoming out in the blind hole.

• For a standard front made of MDF or chipboard with a thickness of 16 mm, a 20 mm screw is typically used.
• For a front thickness of 19 mm, a 22 mm screw is used.
• Many high-quality furniture knobs are supplied with snap-off segmented screws. These feature threadless neck sections every few millimetres. They can be cut cleanly to the exact length needed using pliers.

Installation Guide: Professional Retrofitting

Achieving a clean cut in coated furniture boards requires the correct technique. A blunt drill bit will tear through a melamine resin coating like a blunt knife through fresh bread. Follow this method for a tear-out-free installation.

Required Tools

• Cordless drill driver or drill
• Hole saw (matching the exact diameter of the cable grommet, e.g. 60 mm or 80 mm)
• Wood drill bit (4 mm or 5 mm) for the furniture knobs
• Cross-head screwdriver (PZ or PH, depending on the screw head)
• Folding rule and pencil
• Masking tape

Step 1: Positioning the Cable Grommet

Measure the position on the top panel or back panel of the unit. Ensure that no vertical dividers, cam lock connectors, or drawer runners are in the way beneath the intended hole. Cover the planned drilling area generously with masking tape. The tape prevents chipping on delicate coatings. Mark the exact centre point onto the masking tape.

Step 2: Pilot Drilling

Position the hole saw. The hole saw features a pilot bit in the centre. Drill into the wood at a strict right angle. IMPORTANT: Do not drill completely through the board in one go. As soon as the tip of the pilot bit breaks through the underside of the panel, stop drilling immediately.

Step 3: The Reverse Cut

Remove the hole saw from the opening. Move to the underside (or inside) of the furniture panel. Insert the pilot bit of the hole saw into the small pilot hole that broke through, and continue drilling from this side. Drilling from both sides prevents the teeth of the hole saw from tearing out large flakes of veneer or melamine as they exit.

Step 4: Inserting the Grommet

Remove the masking tape and clear any sawdust from the cut edge. Push the metal outer ring of the cable grommet into the hole. It should fit snugly. If the hole has turned out marginally too large, you can secure the ring with a dab of assembly adhesive or silicone on the inside. Route your cables through and insert the cover with the brush seal.

Step 5: Replacing the Furniture Knobs

Loosen the screws of the old handles on the inside of the front panel. Clean the surface around the old screw hole. Push the new M4 screw from the back through the existing hole. Place the new metal knob onto the front and tighten the screw by hand using a screwdriver. Do not use a cordless drill for this final step, as it can easily strip the fine internal thread of the metal knob.

Frequently Asked Questions (FAQ)

Can I install a rectangular cable grommet without a router?

Yes. A jigsaw is entirely sufficient for rectangular or square outlets. Drill a hole in each of the four corners of the marked rectangle (for example using a 10 mm drill bit). Insert the jigsaw blade into one of the holes and cut along your marked line to the next corner.

What size cable grommet do I need for a TV plug?

A flat two-pin plug (commonly found on many televisions) passes through a 60 mm opening with ease. However, if several HDMI cables with bulky plugs plus network cables must pass through together, an 80 mm opening is recommended to prevent jamming.

What should I do if the pre-drilled hole is too large for the new knob?

If the previous handle was fitted with a thick sleeve and the hole in the front is now larger than 5 mm, the new M4 screw will have too much play. In this case, place a matching metal washer under the screw head on the inside of the front. On the outside, the base of the new knob must be wide enough to completely cover the drilled opening.

Why is the coating chipping during drilling despite using masking tape?

If the surface coating is tearing, the drill speed is often too low or excessive downward pressure is being applied. Work at a higher rotational speed while applying only light pressure. Let the sharp teeth of the hole saw do the cutting. Drilling from both sides (as described in Step 3) is the most effective safeguard against tear-out.

Do metric screws fit into old wood screw threads?

No. If the previous wooden knob was fastened with a wood screw that threaded directly into the knob material, the furniture front usually only has a simple clearance hole (often 4 mm or 5 mm). The new metric M4 screw is simply pushed through this hole to engage with the metal internal thread of the new knob. The old thread in the wooden knob is no longer relevant.

Can cable grommets be installed in solid wood?

Yes, installation in solid wood follows the exact same process as in chipboard or MDF. With hardwoods (such as oak or beech), it is even more important to lift the hole saw clear periodically to clear out sawdust. Otherwise, frictional heat can scorch the wood and cause black discolouration.

Related Guides and Categories

To complete your furniture upgrade project, explore our range of dedicated hardware for professional cable management and cabinet enhancements:

• All Furniture Cable Grommets
• Desk Cable Grommets
• Plastic Cable Grommets
• Cable Grommets with Matte Satin Finish
• Brushed Steel Cable Grommets