Concealed Hinges: Bore Distance, Overlay, and Face Frame vs Frameless

July 19, 2026  ·  by CabiAI  ·  about 8 min read

Short version, so you can get back to the machine: a European concealed hinge needs a 35 mm cup bored about 13 mm deep into the back of the door, set back 3–7 mm from the door edge — and that setback is measured to the edge of the hole, not its center. Two hinges up to roughly 35" of door height, three above that.

Everything else — overlay, plate height, opening angle — depends on one question that splits the whole topic in half: does your cabinet have a face frame, or is it frameless? The same hinge does not work the same way on both, and that is where most of the expensive mistakes live.

Yes, the hardware is metric. Even in the US.

This trips up a lot of American shops. Concealed hinges came out of the European 32 mm system, and the whole category stayed metric worldwide. Your cup is 35 mm — not 1-3/8", which is 34.9 mm and close enough that Forstner bits get sold both ways. System holes are 5 mm on 32 mm centers. Plate heights step in 3 mm. Buy the metric bit: the 1-3/8" will physically work, but the cup sits slightly loose and the two screws end up doing structural work they weren't meant to do.

How many hinges per door

Hinge count follows height and weight, not width. More hinges means the door resists warping over the years. This is a safe starting point for a standard 3/4" (18–19 mm) melamine or plywood door:

Two exceptions. A heavy door — glass, painted MDF, thick slab fronts — gets one more than the table says. And a very wide door on two hinges will lean out at the latch edge even if it's short. An extra hinge costs a few dollars; a callback costs a morning.

Boring the cup: three numbers

Diameter — 35 mm, always

Blum CLIP top, Hettich Sensys, Grass Tiomos, Salice — all 35 mm. This is the one number in cabinet hardware you can treat as universal.

Depth — 12 to 13 mm

Deep enough that the cup seats flush, shallow enough that you don't blow through the face. In a 3/4" door that leaves around 5–6 mm of material in front of the cup. On a 1/2" (12 mm) door it doesn't work at all — thin doors need a hinge rated for them, not a shallower bore into a standard hinge.

Bore distance — 3 to 7 mm, and here's the gotcha

Bore distance is measured from the door edge to the near edge of the 35 mm hole. Not to the center. Blum's charts, Hettich's charts, everyone's charts use the hole edge. So a 5 mm bore distance — the most common default — puts the center of your cup at 22.5 mm from the edge (5 + 17.5).

Shops that program a CNC from a hole-center coordinate and type 5 mm instead of 22.5 mm bore straight out through the door edge. It's an easy mistake to make once, and only once.

The tradeoff: a smaller bore distance gives you more overlay, a larger one gives you less. Below 3 mm the wall between cup and edge gets thin, and that's exactly where a melamine front chips or a painted MDF front cracks under screw pressure. Stay at 3 mm or above and let the mounting plate do the fine work.

The other half of the hinge: the mounting plate

A concealed hinge is two coordinated positions, not one. The cup goes in the door; the mounting plate goes on the cabinet. Get one right and the other wrong and the door will never hang square, no matter how long you spend on the adjustment screws.

In a frameless cabinet the plate screws to the inside face of the side panel, usually onto 5 mm system holes bored 37 mm back from the front edge (some plates use 32 mm — check the one you actually bought). Those holes sit on the 32 mm vertical grid, which is the point of the system: shelf pins, plates, and drawer runners all land on the same line.

Plate height is your overlay dial. Plates come in 0, 3, 6, 9 mm and up, each step pulling the door in by roughly that much. A 0 mm plate with a 5 mm bore distance on a full-overlay hinge lands in the neighborhood of 1/2"–3/4" (13–19 mm) of overlay, depending on series. Pull the actual overlay chart for the hinge you're buying — this is the one place where "about right" isn't.

Face frame vs frameless: what actually changes

Most American shops still build face-frame cabinets. Most of the concealed-hinge literature is written for frameless. That mismatch causes a lot of confusion, so here it is plainly.

Frameless (Euro / full-access): the door covers the edge of the 3/4" side panel. Overlay is measured off that panel edge. Standard Euro hinge, standard plate, screwed to the panel face. Clean, fast, fully drillable on a CNC in the same operation as the rest of the part.

Face frame: there is no panel edge to overlay — there's a frame stile, typically 1-1/2" or 2" wide, and the door overlays that. You have two options:

• A dedicated face-frame hinge — Blum COMPACT 39C, Salice and Grass equivalents. The arm wraps around and screws directly into the edge and face of the frame. Same 35 mm cup in the door, completely different cabinet-side geometry. No plate, no system holes.
• A standard Euro hinge on a face-frame adapter plate, which screws to the frame and re-creates the frameless mounting position. Useful if you want one hinge in inventory for both cabinet types, and it keeps the full three-way adjustment.

The number that changes most: on a face frame, two doors sharing a stile leave each about 3/4" to cover, so 1/2" overlay is the practical standard. Frameless, you're overlaying a 3/4" panel shared by two doors — which is what forces the half-overlay hinge below.

Honest take on which to build: face frame is more forgiving on site, since the frame hides a lot of out-of-square wall, and it's what many US customers expect visually. Frameless gives more usable interior, fewer parts, and it machines cleaner. Already cutting on a CNC with customers who don't demand a traditional look? Frameless is less work per box. Matching existing cabinetry or building inset in a period kitchen? Face frame, and that isn't a compromise.

Overlay, half overlay, inset

Three hinge cranks, three geometries, not interchangeable:

• Full overlay — one door per cabinet side, covering the panel edge. The default.
• Half overlay — two doors sharing one partition, each covering half of it.
• Inset — door sits flush inside the opening. Least forgiving: the reveal has to be even all the way around and the box has to be square.

The classic failure: two doors meeting on a shared 3/4" partition with full-overlay hinges ordered for both. Each door wants the whole panel. They collide, or you shim them apart and leave a gap you can see from across the kitchen. Half-overlay hinges exist for exactly this and cost the same.

Opening angle — and the corner cabinet trap

110° is the standard and covers almost everything. Reach for others in specific cases:

• 155° — corner and blind-corner cabinets, and any door that must swing clear so a pull-out behind it comes all the way forward.
• 95° or so — thick doors and profiled fronts that bind at wide angles.
• 170° — appliance panels and doors that need to lie nearly flat against the run.

The one that gets discovered on installation day: a 110° door next to a perpendicular cabinet in a corner opens far enough to look fine, but the door edge swings into the adjacent cabinet's face and stops — or marks it. Shops often find this only after the boxes are hung and the doors are already bored. Check swing clearance in the design, not in the kitchen.

Adjustment: three screws, one right order

The beauty of the European hinge is that everything is fixable after installation, without removing anything. Typical ranges: about ±2 mm side to side, ±2 mm in height, roughly -0.5 to +2.8 mm in depth.

1. Height first — usually at the plate. Get every door in the run to the same top line.
2. Depth second — moves the door toward or away from the box, fixing a door that stands proud on one side.
3. Side last — closes the vertical gaps between doors.

Do it in that order. If you start with the side screw, every height correction afterwards throws off the gaps you just dialed in, and you'll go around twice.

Soft close: when to skip it

Integrated dampers — Blum BLUMOTION, Hettich Silent System, Grass Tiomos with its adjustable damping — are effectively standard now, and on a kitchen you should just spec them. The honest exceptions:

• Very light doors sometimes lack the mass to close fully against a damper. Most systems have a damping adjustment or a deactivation switch — use it.
• Garage, utility, and shop cabinets. Nobody is paying for a quiet close on a plywood shop cabinet. A plain 110° hinge is genuinely enough.
• Retrofits where the hinge stays — clip-on damper adapters fix it for a couple of dollars per door, no re-boring.

Where this gets automated

Every number above is correct, and every one of them shifts with door height, overlay type, door thickness, and hinge series. Re-deriving them per door, per cabinet, at six in the evening is precisely the task that produces the mistakes this article is about.

CabiAI sets hinge count from door height and derives both positions — cup in the door, plate on the cabinet — from the overlay type you picked, so the two halves always come out of the same calculation. The holes go straight into the DXF/NC output, on the same nested sheet as the rest of the parts. You still need to know what's right. You just stop recalculating it for every door.