David Dundas, Elimbah, Qld

Zenwood Rocking Chair
Jarrah

Concept
The zigzag concept originated from the Gerrit Rietveld Zigzag chair. My first attempt at a zigzag rocker was built with the lower end of the legs joined to the balance point in the middle of the rockers, and with parallel rockers. A member of the Australian Woodworking Forum, with the appropriate login-ID Zenwood, suggested reversing the Z’s, and attaching the legs to the front end of the rockers; so this chair is named after him. The splay of the Z-assemblies made the provision of stretchers between the legs difficult, because of the compound angles that would be involved in their joinery; so it was decided to support the seat/back assembly with housing joints, instead of resting the seat rails on a stretcher.

Materials
The chair is built of jarrah (Eucalyptus marginata), with back slats and mitre keys of silver ash (Flindersia bourjotiana). The slip-seat frame is made of mountain ash, and is upholstered in leather over foam and elastic webbing. The timber was purchased from Lazarides Timber, Brisbane.

Joinery
The cross rails are all dominoed. The ends of the back rails are angled at 83° to their (original) front faces, in order to splay the seat sides, the arms, and the rockers.
The 29.5° mitre joints joining the legs to the rockers are aligned with a domino, and reinforced with twin 3.5mm thick keys glued into saw kerfs, and pinned with brass screws.
Four mitre keys provide a total gluing area of approximately 160 square centimetres, not including the area of the mitre faces. The kerfs for the keys were cut using a tenoning jig on the tablesaw.
The 27° mitres joining the arms to the legs are reinforced with a domino. The mitres on the legs and arms were cut using a triangular jig clamped to a Kreg mitre gauge. The mitres at the front end of the rockers were cut with a backsaw, and then planed to the mark-out lines with a block plane.
The seat side-rails are joined to the legs with interlocking housing joints reinforced by a screw; and the leg/arm mitres are glued into housings in the back stiles, reinforced by twin screws. The rockers and back-slats are glued laminations. The back-slats are set in mortises in the back rails.

Glue
All the joints and laminations were glued with Techniglue CA epoxy.

Finish
The finish consisted of four coats of Minwax wipe-on poly, waxed with Ubeaut traditional wax, rubbed in with fine steel wool.

Photo: David Dundas