CHAPTER VIII 



JOINTS IN WOODWOKK 



The proper connection of the different timbers used m building work 

 is of importance. In designing and making joints in woodwork 

 the following leading principles should be kept in view : — 



1. The joint should be cut, and the fastenings arranged, so as 



to weaken the timbers which are joined as little as possible. 



2. Any abutting surfaces, in a joint, which are subject to pressure 



or compressive stress, should be disposed at right angles to 

 the direction of that pressure. All surfaces, but especially 

 the above-mentioned abutting surfaces, should be accurately 

 fitted to each other. 



3. The fastenings and bolts should be properly proportioned, 



and arranged to the best advantage. It should be 

 remembered that the boring of a hole to receive a bolt 

 severs some of the fibres of the timber, thus diminishing 

 its strength. 

 Only a few joints, being those most applicable to farm purposes, 



will be discussed. 



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Scarfed or Spliced Joints. — Timbers may be joined, so as to 

 form one long piece, by the use of scarfed or spliced joints. 



The simplest type of scarfed joint is illustrated by Fig. 74. 

 Half the thickness of the end of each timber is cut away, 

 and the remaining parts are overlapped and bolted together. ^- - ^ 

 This is known as halving, and the joint is termed a halved 

 or half -lap joint. This joint is suitable to resist compression, 

 but any cross, bending, or tensional stress is thrown entirely 

 upon the bolts. 



The joint shown in Fig. 75 has the surfaces ah cut to a FlG ' 

 bevel. If the bolts are tightly screwed up this bevel helps the joint 

 to resist a pull or tension. 



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