Scarf joint

The ends of a plain scarf are feathered to a fine point which aids in the obscuring of the joint in the finished work, while in other forms of scarf the ends are frequently cut to a blunt "nib" which engages a matching shoulder in the mating piece.

A plain scarf is simply two flat planes meeting on an angle relative to the axis of the stock being joined, and depends entirely on adhesive and/or mechanical fasteners (such as screws, nails, or bolts) for all strength.

The plain scarf is not preferred when strength is required, so it is often used in decorative situations, such as the application of trim or moulding.

The keyed-hook scarf is common in ship and boat-building,[2] as well as timber framing and wooden bridge construction.

In large timbers such as these the scarf is virtually always secured with through bolts, and is frequently reinforced externally with iron or steel fishplates, and/or strapping.

A scarf joint may also be used to fix problems caused when a board is cut too short for the application.

A plain scarf joint
A nibbed scarf joint
A keyed, nibbed scarf, reinforced with fish plates and through bolts
The scarf joint used on the beams above the post is known by its French name, trait de jupiter , or bolt-o-lightning joint .