CONSTRUCTION FIXINGS Joyner Bolt™
became frustrated with the limitations of traditional UK methods of securing structural timber.
W
“ Joyner Bolt is a task specific, engineered fixing designed by users for users.”
Daniel is a chartered surveyor and managing partner in a
building design consultancy based in Cambridgeshire; Mark, an established construction professional in the same region. Thrown together on a building project designed by one and delivered by the other, the result was a critical scrutiny of the structural, aesthetic and purely practical difficulties in using traditional UK construction methods, and the germ of a design to solve them. A work book full of drawings, a series of homemade prototypes and, in the final stages, the assistance of Barton Coldform in refining the design to make it capable of series production and Joyner Bolt samples began to land on merchants and users desks during the first months of 2012. The limitations that catalysed the Joyner Bolt will be
readily recognised by anyone working with timber structures. Using a coach bolt to secure timber members demands correctly sized and accurately aligned holes, something in practice rarely to be relied upon. Coach bolts commonly turn within the timber before the joint is completely and correctly tightened. It is also very common for the relatively small head to be pulled into the wood used commonly
gets to grips with UK timber construction
Like many remarkable innovations Joyner Bolt™ was born from the frustration of hands-on practitioners. Also like many inventions that go on to stand the test of time, the solution appears remarkably simple – once, of course, someone has thought it up.
hich makes light of a long development that has demanded a depth of financial, personal and technical commitment certainly never anticipated when Daniel Hardingham and Mark Doye first
in UK construction, reducing the effective structural depth of the timber as designed. The domed head can also presents difficulties in fixing finishing materials such as plywood or plasterboard. Threaded rods also have drawbacks – including wastage, as the entire rod is rarely used; deformation of the thread when the rod is cut; and the need for additional nuts and square washers. Rotation when tightening can also be an issue, drawing the rod through the timber resulting in uneven protrusion of the thread. In contrast the Joyner Bolt is a task specific, engineered fixing
designed by users for users. Its distinctive feature is a 45mm square, spiked head incorporated to a grade 4.8 cold-formed metric coarse threaded shank. The standard range currently comprises 23 sizes, ranging from M8 to M16 in diameter, and from 80mm to 205mm in length although, given sufficient demand, production of special dimensions is quite feasible. Joyner Bolts are UK manufactured and carry a minimum 9 micron of Chrome 6 free zinc plating. There are two versions of the Joyner Bolt covering the same size range – one fully threaded, the other incorporating a slot at the end taking the nut. The underhead spikes, spaced around the edge of the 3mm
deep square head engage into the timber – finger pressure is generally adequate but additional security is ensured simply by tapping with a hammer. Dislodging the Joyner Bolt when the two timber members are brought together is rare, unlike a coach bolt that can all to easily be knocked back through the hole and in some cases lost forever. The large face compensates for oversized holes and a square washer and nut are easily fitted to the other end. Tightening the nut is a one- handed operation: the Joyner Bolt resists rotation as the spikes embed deeper into the timber surface and the wide face provides the resistance to ensure correct torque is applied to the assembly. The end result is an
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Fastener + Fixing Magazine • Issue 75 May 2012
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