Cladding, flooring and stairs on a CNC bridge saw

The work

Architectural stone work is mostly straight cuts in large numbers: wall cladding panels, floor tiles, skirting and strips, window sills, copings, stair treads and risers. The pieces are simple, but every one has a position number on the shop drawing, and many need secondary work: a chamfer, a drip groove, a kerf for the fixing, or a 45° joint at an external corner.

Multi-cut and strip programs

A CNC bridge saw handles this with parametric programs instead of a DXF per piece. The operator enters strip width, piece length and quantity, and the saw:

1. Trims one long edge of the slab straight.
2. Rips the slab into strips (multi-cut in X).
3. Turns the head 90° with the C-axis head rotation and crosscuts the strips to length.

A vacuum manipulator separates the strips after the rip cuts, so the crosscuts do not trap pieces or chip the ends. Without it, the operator stops the saw to pull strips apart.

Kerf loss counts on small pieces. Every cut removes one blade width, so a slab cut into 100 mm skirting strips loses more material to kerf than the same slab cut into 600 mm panels. Put the kerf into the yield calculation before quoting.

Edge work: chamfers and drip grooves

• Chamfers and eased edges. With the A-axis tilted to 45°, the blade cuts a small chamfer along the top edge of a tile, tread or panel. This replaces hand work with a grinder and gives a constant width.
• Drip grooves. Window sills, copings and exterior soffits need a groove on the underside near the front edge, so water drips off instead of running back to the wall. The saw cuts it with the slab face down at a set depth. The NBGQA specification asks that moldings, washes and drips have a constant profile over their full length, which is easier to hold with a CNC cut than with a hand saw.
• Anti-slip grooves on stair treads near the nosing are cut the same way, at shallow depth.
• Rodding grooves are used on long, narrow pieces such as sills, as on countertops.

Fixing kerfs and undercut anchors

Ventilated cladding is hung on metal fixings. Two common systems:

• Kerf fixings. A continuous kerf or anchor slots are cut into the top and bottom edges (beds) of the panel, and an agraffe or clip engages in the kerf. On a CNC bridge saw, this needs the A-axis tilted to 90° so the blade runs horizontally into the edge of the panel lying on the worktable. The kerf position from the face must be accurate, because it sets the face alignment of the whole wall. Depth is limited by the blade flange and head clearance; check this for your panel thickness.
• Undercut anchors. A cylindrical hole is drilled into the back of the panel, not through it, and undercut conically so the anchor sits form-fitting. The KEIL system uses a 7 mm bore with a 9 mm undercut and is offered for panels from 6 mm thick. The hole is made with the anchor maker’s drilling tool. ETA-16/0096 covers this anchor for rear fixing of porcelain stoneware façade panels. This is normally done on a drilling station, not on the saw.

Laminam also describes a hidden mechanical safety holder in a kerf cut into the back of the slab, for exterior wall tiles fixed with adhesive.

Stair treads and risers

Stair sets mix thick treads, thin risers and landings, each with its own size. The saw cuts treads to length and depth, chamfers or profiles the nosing and cuts anti-slip grooves. Where the tread and riser are joined at 45°, both pieces are mitered on the saw. Laminam specifies two-component epoxy for this joint and a bevel of at least 2 mm after curing. See mitered edges for miter accuracy.

Dimensional tolerance

Architectural work is checked against the shop drawings and the project specification. The NBGQA specification for architectural granite is one common reference:

Item	Tolerance (NBGQA)
Panel face dimension	±1.5 mm (±1/16 in)
Out of square (max.)	1.5 mm (1/16 in)
Panel thickness 20–41 mm	±3 mm (±1/8 in)
Panel thickness 10–13 mm	±0.8 mm (±1/32 in)
Continuous kerf, width and depth	±1/16 in (about ±1.5 mm)
Anchor slot, face to centerline	±1/16 in (about ±1.5 mm)
Anchor slot depth (max.)	±1/8 in (about ±3 mm)
Back anchor depth	-0, +1.5 mm
Sawn beds and joints	within ±3% of 90° to the face

The tolerances assume panels up to 4 in (102 mm) thick, not larger than 5 × 5 ft, and sawn on all six sides. A CNC bridge saw holds face dimensions and squareness well inside these values. It does not correct thickness: thickness comes from the gangsaw or calibrating machine that made the slab.

When a multi-blade line beats a single-blade saw

Be clear about volume. A single-blade CNC bridge saw makes one cut at a time. A dedicated tile line puts several blades in each pass. One example, a Barsanti line listed for resale, has a long-cut bridge with 7 blades and a cross-cut bridge with 11 blades, an automatic slab loader, conveyors and a dryer. It is about 36 m long and the listing gives a capacity of around one slab per minute, for slabs up to 3,500 × 2,100 × 50 mm and tiles from 300 × 300 mm.

A single-blade saw needs many minutes for the same slab. For a plant that produces standard floor tiles or strips every day, a multi-blade line, or a multi-blade bridge saw with electronic blade positioning, is the right machine. It needs floor space, a loader and steady volume to pay back.

The single-blade CNC bridge saw is the better choice when:

• Sizes change from position to position, as on most cladding and stair projects.
• Pieces need chamfers, drip grooves, kerfs or 45° joints.
• Batches are small and the same machine also cuts countertops.
• Slabs are porcelain or sintered stone, where the slab maker’s feed limits apply to every blade anyway.

Many shops run both: a line for standard formats and a CNC bridge saw for the project pieces.

Next step

Send a typical project schedule (piece list, sizes, edge work, fixing system) through request a configuration and we will tell you whether a single-blade saw fits it. Specifications are on the 5-axis CNC bridge saw page.