How do I cut melamine or veneered board without chipping the surface?

The melamine layer on a faced chipboard, and the veneer on a veneered ply, are thin, hard and brittle, and they are bonded to a soft core. Where a tooth enters the surface it is pressed down against the core and cuts cleanly. Where it exits, it lifts the surface away from the core with nothing behind it, and a flake breaks off. Every technique below is a way of supporting that surface at the moment the tooth breaks out.

What you'll need

• Fine tooth count blade, TCG grind
• Straightedge or saw guide
• Clamps
• Low-tack masking tape
• Scrap sheet for backing
• Sharp knife (optional)

Step by step

1. Work out which face chips on your saw.The face the teeth exit through is the one that chips. Hand-held circular saw: teeth travel upwards through the work, so the top face chips — good face down. Standard jigsaw blade: cuts on the upstroke, top face chips — good face down. Table saw: teeth travel downwards, so the underside chips — good face up.
2. Fit the right blade.A high tooth count with a triple-chip grind (TCG) is the correct blade for melamine, laminate and solid surface. The flat-topped teeth pre-cut the brittle face and the chamfered teeth clear the waste, and the usually negative hook angle stops the blade snatching at the surface.
3. Score the line before you cut it.Set the blade barely proud of the surface — a millimetre or so — and run the full cut along the guide at that depth first. That severs the melamine cleanly with the fibres fully supported beneath. Then raise the blade to full depth and run the same cut again in the same kerf. This single step does more than everything else combined.
4. Tape the cut line.Low-tack masking tape stuck along the line on the face that will chip holds the surface fibres down as the teeth break through. Mark your line on the tape and cut through it. Peel the tape off along the cut, not across it, or it lifts the chips it was holding.
5. Back the cut with sacrificial material.Clamp a piece of scrap ply or MDF hard against the face that chips, so the surface is supported right up to the kerf and the teeth exit into the scrap rather than into air. On a table saw this is a zero-clearance insert; by hand it is simply a board clamped underneath.
6. Score by hand for a short cut.For a small cut, run a sharp knife along a straightedge two or three times, hard enough to sever the melamine layer, on both faces if the saw will exit through both. Then cut just inside the scored line.
7. Feed steadily and let the blade do the work.A slow, hesitant feed rubs and heats the resin surface, which then chips more, not less. A steady moderate feed with a sharp blade is what you want, and the cut should be one continuous pass.
8. Deal with the cut edge.Even a perfect cut leaves a raw core edge. Iron-on edging tape, a T-moulding or an edge strip covers it; trim edging flush with a laminate trimmer, a sharp block plane or a purpose-made edge trimmer, working from the middle outwards so you do not lift the end.

Tips

• For a jigsaw, a down-cut blade reverses which face chips, which is exactly what you want for cutting an aperture in a fitted worktop where the good face has to be uppermost. It also makes the saw try to lift off the work, so clamp and hold it down.
• A router with a straight bit and a clamped guide gives the cleanest possible edge in melamine, because the cutter shears rather than chops — worth it on visible edges.
• Both faces of a melamine board chip on a circular saw if the cut is not scored, because the blade exits through the top and the trailing edge of the kerf lifts the bottom face at the end of the cut. Score, tape or back both faces on a visible panel.

Common mistakes

• Using a general-purpose 24-tooth blade — Each tooth takes too big a bite for a brittle surface and shells the melamine off in flakes wider than the kerf.
• Cutting good face up with a hand-held circular saw — It puts the visible surface exactly where the teeth break out. Turn the board over.
• Peeling the tape across the cut — It lifts the very chips it was holding down. Pull it off parallel to the cut, slowly, at a shallow angle.
• Relying on tape alone — Tape helps a good blade and cannot rescue a coarse one. The blade and the scoring pass are the substantive fixes.

Questions people ask