FKOST COGS. 



165 



A mould, the holes in which have been made by the counter- 

 sink, is necessary ; the steel rod is slightly warmed and drawn 

 until it will enter the mould to within about one-twentieth 

 of an inch of the end. A sufticient length is then left pro- 

 jecting and the bar so deeply notched that it can easily be 

 broken off. This may be done immediately, and the cog 

 cooled, a blank resulting ; or if a chisel edge is required, the 

 cog is grasped with special tongs having short jaws bored 

 out to receive the shank, and the chisel edge is then formed 

 with a hammer. 



It is much easier, however, not to give the shank a conical 

 form, but merely to produce a chisel edge and to cut off the 

 cylindrical cog thus formed. Diamond-headed cogs are pro- 

 duced on an oblique tool, similar to that in fig. 142, b, by using 

 a special hammer and turning the bar frequently. 



The cogs (fig. lo7) can easily be cut to the same length by 

 fixing a stop at the necessary 

 distance in front of the cutter. 

 They are made on the anvil shown 

 in fig. 114, it l)eing only neces- 

 sary to have proper moulds and 

 a proper hammer. Before nail- 

 ing on the shoes the cogs should 

 be tried. They are well made 

 when the shanks fit tightly all 

 round and their ends fill the en- 

 tire hole, with the exception of a 

 space of J^ to ^ inch at the upper surface of the shoe. The 

 coo^s are insertecl after shoeiuo; : the first introduced can be fixed 

 by means of a light blow ; in inserting the second, however, it 

 is necessary to press gently on the first, which might otherwise 

 jump out under the shock of hammering. All that is necessary 

 to insure their holding is care in manufacture and fixing. 



(b) Quadrangular cogs were suggested by Dominik of Berlin. 

 In usina' cosis of -3- inch thickness in the shank, a hole is 

 punched through the heel of the shoe by means of a square, 

 moderately conical punch, the end of which measures, say, ^ 

 inch ; this hole is enlarged with a drift. The holes should be 

 punched from the ground surface, care being taken to hold the 

 tool at right angles to the surface of the shoe. 



Fig. 137.— Rountl sharp cogs, a, for 

 tlvaught; h, for riding horses (nat. 

 size). 



