When the excentric-rod is disconnected from the gap-pin, the guard, which is fixed by screws to the underside of the excentric-rod, forms a parallel path, in which is the gap-pin, instead of being in the excentric-rod gap. Very little abrasion attaches to the guard, consequently, it is forged either of iron or of steel that is very fibrous. The guard, with the two screws for fixing, are shown by Fig. 20.

The guards are made of thin bars of suitable width and thickness, which are then bent to the shape desired. This bending is named cranking. There are several ingenious modes of cranking adopted by smiths ; of these methods it is necessary, in this place, to mention only one, which is suitable for a thin, flat bar, and consists in first forming the two outside bends which are nearest to the two ends of the guard, and afterwards making the two inner bends or curves.

The two outer bends are effected by heating the iron or steel to a bright yellow, and cooling to an equal distance on each side of the spot intended to be the centre or middle of the intended curve, named the corner ; the cool end is then placed into a slot in a heavy block, and the work bent while therein.

The length of iron placed into the slot is the length of the end required ; and while one end is in the slot, the opposite end is in a tongs, shown by Fig. 100. The tongs, and the work to be bent, together constitute the lever by which the smith bends the iron to a right angle; after which, the corner is shaped by applying a flatter or a set-hammer. If a long curve is desired, instead of a sharp angular corner, the end of the piece to be bent is put into a slot having curved edges, instead of into a slot with angular edges, which is necessary to produce a sharp or square corner. There is also a difference in the length of iron which remains heated after being cooled to the proper distance. For a small corner, the length of the heated part is only sufficient to allow the tar to be bent without the risk of cracking. For a longer curve, or curve of longer radius, the length of the heated portion is about the same as the length of the curve required; if not, the iron will require to be re-heated, and cooled to proper distances from the corner, in order to make the curve to the correct length.

When one end of the work is thus bent to a right angle, the bent part is fixed in tongs resembling Fig. 101, and the opposite end of the piece is bent in a similar manner, so that the two bent portions, or arms, will be on the same side of the work. The two inner bends are next effected by placing the work, while heated, between two studs or pins loosely situated in two slots or holes in the heavy cast-iron block. In some cases, the two studs constitute one solid tool,, having a square stem to fit the square hole in the anvil.

The two inner bends are produced by similar careful heating and cooling, to make the curves of the correct length ; and by bending in the opposite direction to that of the two previous operations, the two cranks in the work are made.