Tuesday, March 25, 2014

Timber Works 04-Timber Joints

Timber joints are used to join timber parts in a structure. Timber needs to be joined in 03 positions when making timber structures:
1.      Lengthening
2.      Widening
3.      Angled or Cross
Halving Joints
A halved joint is formed by removing material from each at the point of intersection so that they overlap. The two members can be joined either on the flat or on the edge. When joined on the flat it is termed a lap joint.
The simple halved joint is created by cutting a slot in opposite edges of the members to be joined so that they slip together. Most commonly, the amount of material removed is equal to half the width of the members being joined, although this depends on the relative dimensions of the members. This joint is relatively weak and prone to splitting, due to the lack of shoulders which would otherwise prevent twisting. When extra strength is required, a strengthened version of the joint is called for. This involves a more elaborate cut out which incorporates shoulders to prevent twisting of the joint.

                 End Lap Joint                                                                       Tapered end lap joint

                           Halving joint with bolts                                             Angled halving joint

     Cross halving joint                Dovetailed cross halving                   Oblique halving

Mortise &Tenon Joints
The mortise and tenon joint is one of the oldest timber joints. This joint is used to join pieces of wood, mainly when the adjoining pieces connect at an angle of 90°. In its basic form it is both simple and strong. Although there are many joint variations, the basic mortise and tenon comprises two components: the mortise hole (female) and the tenon (male). A mortise is a cavity cut into a timber to receive a tenon. The mortise is usually 1/3 thickness of the member. A tenon is a projection on the end of a timber for insertion into a mortise. Usually the tenon is longer than it is wide. The tenon, formed on the end of a member generally referred to as a rail, is inserted into a square or rectangular hole cut into the corresponding member. The tenon is cut to fit the mortise hole exactly and usually has shoulders that seat when the joint fully enters the mortise hole. The joint may be glued, pinned, or wedged to lock it in place.

Haunched Mortise &Tenon                                                                   Wedged Mortise &Tenon

Bridle joint
Bridle joint is similar to mortise &tenon, in that a tenon is cut on the end of one member and a mortise is cut into the other to accept it. The distinguishing feature is that the tenon and the mortise are cut to the full width of the tenon member. The corner bridle joint (also known as a slot mortise and tenon) joins two members at their respective ends, forming a corner. This form of the joint is commonly used to house a rail in uprights, such as legs. It provides good strength in compression and is fairly resistant to Stacking, although a mechanical fastener or pin is often required. Corner bridles are often used to join frame components when the frame is to be shaped. Material can be removed from the joined members after assembly without sacrificing joint integrity.
A variation of the bridle joint is the T-bridle, which joins the end of one member to the middle of another.


Corner Bridle Joint

‘T’ Bridle joint.

Timber products.
Timber products are the structural or non-structural items made out of wood. These are widely used for construction items and house furniture and fittings. The examples are numerous:
1    1.      Doors
2.      Windows
3.      Stairs
4.      Tables
5.      Cupboards
6.      Roofs
7.      Partitions
8.      Floors

Door                                       Window                                              Stair
Table                                                              Cupboard


Timber Roof                                                              Timber Partition



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