Tongue-and-Groove Octagonal and Star Pine Assemblies: Geometric Lattices & Polyhedral Tenons in Kündekari

At the core of every kündekari assembly lies the sophisticated mathematical language of girih—the traditional Islamic system of geometric strapwork and polyhedral tile patterns. Pioneered by medieval Islamic mathematicians and master builders, girih relies on a vocabulary of five fundamental polygons: the regular decagon, elongated hexagon, bowtie, rhombus, and regular pentagon. When translated into three-dimensional woodwork, these geometric formulas dictate the exact angles and lengths of every interlocking rail and floating panel.

In Anatolian Seljuk practice, the eight-pointed star (sekizgen yıldız) and twelve-pointed star (onikigen) reigned supreme. To construct these configurations, the master woodworker drafted interlocking radial circles using precision brass dividers on full-scale timber parchment boards. Every intersection point represents a structural joint where multiple grooved framing rails meet, requiring exact angular tolerances down to fractions of a degree to prevent compounding errors from distorting the overall rectangular door leaf.

The mechanical brilliance of hakiki kündekari resides in the relationship between the kiriş (grooved framing batten) and the tabla (polygonal panel). The kiriş is a slender wooden rail, typically measuring 10 to 14 millimeters in thickness and 18 to 25 millimeters in width, into which continuous parallel grooves are plowed along both lateral edges. Where rails cross one another at star vertices, they are joined via intricate half-lap miters and locking bridle notches that prevent lateral displacement.

The central star and octagonal panels are fashioned with continuous stepped tongues machined around their entire perimeter. These tongues are dimensioned to slide snugly into the kiriş grooves with approximately 0.5 to 1.0 millimeter of lateral clearance and 1.5 millimeters of bottom depth clearance. This loose-tenon engagement creates an extraordinary engineering marvel: the panels physically brace the framing rails against twisting, while the rails lock the panels into a continuous, self-supporting architectural diaphragm without a single mechanical fastener.

Before the advent of motorized spindle moulders, Seljuk and Ottoman artisans executed these thousands of micro-joints using highly specialized hand tools. Master joiners employed custom wooden zivana planes crafted from dense wild service tree or hornbeam, fitted with hand-forged Swedish or Damascus steel irons ground to mirror-image step profiles. These planes cut the groove and tongue simultaneously, guaranteeing uniform cross-sectional dimensions across hundreds of meters of framing stock.

For shaping the intricate concave profiles, bead moldings, and chamfers along the exposed edges of the kiriş rails, artisans utilized çift sıyırgı—traditional brass scratch stocks fitted with custom-filed scrapers. Working with the grain of seasoned pine, the artisan drew the scraper repeatedly along the batten until the profile bottomed out against the tool fence, yielding satin-smooth moldings that required zero abrasive sanding.

Assembling a hakiki kündekari panel is an irreversible, sequential puzzle that must proceed strictly from the interior core outward. The joiner begins by placing the central eight-pointed star panel flat on the workbench and surrounding it with its primary ring of grooved framing battens. Next, intermediate hexagonal kite panels and diamond lozenges are slid into the outward-facing grooves of these initial rails.

Each subsequent layer of rails locks the preceding panels permanently in place. As the lattice expands radially toward the outer stiles, the assembly becomes increasingly rigid yet remains completely flexible within its micro-joints. Once the outer boundary rails are mortised and pegged around the perimeter, the thousands of individual parts become an unbreakable, monolithic structural field—a testament to the supreme mastery of medieval Turkish engineering.