Curved-Waist Solid Pine Case Carving and Bending: Hourglass Joinery of Dalarna Clockmakers

In the world of antique horology, the silhouette of the Swedish Mora clock is unmistakable. While English grandfather clocks and German longcase clocks were engineered as rigid, rectilinear boxes of oak or mahogany, Dalarna joiners treated the pine case as an exercise in sculptural fluid form. The case is a harmonious symphony of curves: starting from a sturdy, flared base (fot), it narrows into an elegant ankle, swells outward into a generous, rounded belly (mage), tapers into a slender hourglass waist, and expands into a circular bonnet hood (huvud).

Achieving this fluid silhouette from solid timber presented a formidable challenge. Rather than relying on modern industrial bending presses or flexible plywood, 18th-century craftsmen utilized subtractive sculptural carving. Massive baulks of slow-grown Scots pine (Pinus sylvestris) were hewn and dimensioned, after which the master joiner carved away the excess wood using curved drawknives, framing adzes, and specialized wooden-bodied compass planes whose soles were curved along both longitudinal and lateral axes.

For particularly voluptuous cases—such as the famous Brudklockor (bridal clocks), which featured sweeping bellies up to 50 centimeters in diameter—carving from a single monolithic baulk was both wasteful and structurally risky due to cross-grain weakness. To overcome this, Dalarna joiners borrowed sophisticated techniques from the ancient craft of cooperage (barrel-making).

The curved sides of the belly were constructed from multiple vertical pine staves. Each stave was planed with compound-beveled edges using long jointer planes. The staves were edge-joined using internal dry pine dowels and hot animal-hide glue, forming a rigid, curved barrel segment that possessed immense strength while following the natural longitudinal grain of the wood. For tighter curves near the neck, carpenters made shallow horizontal kerf cuts along the inside face, steamed the wood over boiling cauldrons, and bent the staves around heavy wooden formers until dry and stabilized.

A tallcase clock is subjected to continuous dynamic forces: the heavy mechanical movement sits at the top, twin lead or cast-iron weights descend within the belly, and the heavy pendulum swings in perpetual oscillation. If the wooden case is poorly joined, this swinging motion induces structural racking, which throws the clock out of beat and stops the movement.

Dalarna carpenters assembled cases without a single iron screw or metal nail, relying on traditional draw-bored mortise-and-tenon joints. Deep rectangular mortises were cut into the vertical stiles to receive the tenons of horizontal stretchers. A hole was bored through the mortise cheeks, and a matching hole was drilled through the tenon, deliberately offset by 2 millimeters closer to the shoulder. When a tapered, dry octagonal pine peg (nar) was driven home with a wooden mallet, the wedge action pulled the tenon into the mortise with crushing mechanical force, locking the three-part case into a rigid, vibration-free fortress.

Scots pine is a living, breathing material that expands and contracts significantly with seasonal fluctuations in atmospheric humidity. In Sweden's sub-arctic climate, summer brings high humidity from lakes and rainfall, while winter brings extreme interior dryness caused by masonry tile heaters (kakelugnar). Tangential wood shrinkage across a wide pine panel can exceed 6% to 8%.

To prevent the case from tearing itself apart, Dalarna joiners incorporated sophisticated expansion details. The large belly door and lower base panels were never glued into their frame stiles; instead, they were engineered as free-floating panels seated within 10-millimeter deep grooves ploughed into the inner edges of the frames. Internal clearance gaps allowed the panels to swell and shrink freely across their width without buckling the frame or cracking the outer gesso finish. This masterclass in vernacular joinery has allowed authentic Mora clock cases to survive over two centuries of severe Scandinavian winter heating cycles without structural failure.