Line Drilling (32 mm Grid): Spacing & Diameter for Shelf Supports

Line drilling based on the 32 mm grid is a standardised system in cabinet making where drill holes for shelf supports, hinges, and runners are spaced at an exact distance of 32 mm from each other. The typical drilling diameter for these continuous rows of holes is 5 mm, whilst the standard distance from the cabinet front edge is 37 mm.

What Exactly Is the System 32?

The System 32 acts as the DNA of industrial and bespoke furniture construction. It ensures that fittings remain compatible across different manufacturers. Instead of calculating individual positions for every single shelf or hinge, joiners use a continuous line of holes along the carcass side panels.

This grid dimension is not limited solely to the vertical adjustment of shelves. The mounting plates of concealed cup hinges, cabinet runners for drawers, and even fixing centres for furniture handles are based on multiples of 32 mm. This results in standard industry handle centre-to-centre dimensions of 96 mm (3 x 32 mm) or 128 mm (4 x 32 mm).

Dimensions and Standards: Spacing & Diameter

Strict geometric guidelines apply to the correct layout of line drilling to guarantee the precise fit of all fittings:

• Hole spacing (vertical): Exactly 32 mm from hole centre to hole centre.
• Drill diameter: Standard 5 mm. Less commonly, primarily in delicate shelving units, 3 mm is used.
• Distance to the front edge: The front line of holes is always located 37 mm behind the front edge of the cabinet carcass.
• Drill depth: For blind holes (non-through holes), the depth is typically 13 mm to 15 mm, matching standard support pins.

Application & Selection of Shelf Supports

The 5 mm hole is primarily designed to accommodate shelf supports. Depending on the shelf material and the required load capacity, different designs are used.

For classic wooden shelves in cabinets, a solid push-in shelf support made of steel or die-cast zinc is sufficient. If shelves need to be secured against sliding or tipping out, fitters use shelf supports with a clamping function or an additional retaining pin that slots into the underside of the wooden shelf.

Care must be taken with glass shelves: bare metal can scratch the surface. Suitable glass shelf supports feature a resting surface made of soft plastic or rubber, protecting the glass whilst providing an anti-slip effect.

For installations requiring extremely heavy load capacities that can no longer be held by a simple 5 mm line of holes inside a cabinet, external wall mounting using a heavy-duty shelf bracket is used instead.

Processing in Carcass Construction

Line drilling is usually carried out before assembling the carcass, using a dedicated multi-spindle drilling machine or a router fitted with a guide rail. If unused drill holes remain visible and disrupt the aesthetic after assembling the furniture and inserting the shelves, they can be plugged.

Whilst small plastic blanking plugs are used for the 5 mm hole line, larger cavities are often created in cabinet making by connecting fittings (such as cam and dowel connectors). These are concealed using matching cover caps, such as cover caps diameter 14mm. For larger system drillings, cover caps diameter 18mm are used accordingly.

The 32 mm grid can be found in virtually every carcass component – from wardrobes to office furniture. When planning the latter, fitters often supplement standardised drilling patterns with functional cut-outs, such as incorporating a cable grommet for desk. However, this falls outside the 32 mm system and is drilled individually using a hole saw (typically 60 mm or 80 mm).

Related Terms

• System 32
• Shelf supports
• Concealed cup hinge
• Hole centres

Matching Categories

• Shelf supports
• Shelving shelf supports
• Glass shelf supports