Although the calk-holes may be punched in a hot shoe, yet boring and reaming them is much better, because by this method a more perfect fit can be secured. For this purpose we require a drill (a spiral drill is the best) whose diameter is exactly the same as that of the small end of the calk-tap (Figs. 165, _c_, and 166, _c_). After the shoe has been fitted to the hoof, the provisional holes are drilled and afterwards reamed out from the ground-surface of the shoe with the reamer shown in Fig. 167. Since the tap of the reamer corresponds exactly in size to the tap of the calk, it is evident that the latter must exactly fit and be tight. The wire edge that is raised around the hole is removed with a file, and the edge then smoothed by introducing the reamer a second time. The calks are made of rolled round steel, which has the thickness of the tap-end of the calk. For this purpose we require a calk-mould or matrix, in which one or more holes have been finished with a reamer. A piece of rod steel is heated at the end for a distance nearly twice the length of the calk, is swaged, thrust into the matrix, then broken off, and back-set. This will give a blunt peg-calk. If a sharp calk is desired, the upper part of the head of the calk is sharpened in the ordinary manner, although this is accomplished most easily by using a pair of tongs with short jaws that are hollowed upon the inside for seizing the tap of the calk. Before the shoes are nailed on, the normal punch should be oiled and driven into the calk-holes, and the calks passed into the holes to see that they fit perfectly. The calks are driven into place =after= the shoes are nailed to the hoofs. A light blow is sufficient to fasten a calk, yet a necessary precaution is first to remove every trace of oil from the calks and calk-holes. The first calk driven into place must be held with the hand while the second is being driven, otherwise it will either spring from the calk-hole or be loosened so that it will soon afterwards be lost. To remove such a calk we strike its head from different sides with a hammer, stone, or other hard object until it becomes loose, when a rather hard blow upon the shoe causes it to spring out. Calks which have worn down are seized by a pair of sharp nippers and loosened by blows upon the shoe. Since a calk which is firm soon rusts and is then very difficult to remove, it is recommended that all calks be removed every night. The =advantages= of peg-calks over screw-calks are: 1. They do not break off. 2. They are easier to make and simpler to use. 3. They are =cheaper=.