(c) Two cups set in the batten frame, which support the cylinder. The cups are made of iron or brass and are held in place by a bolt with thumb screw on the outside of the frame of the batten. Set into the bottom of the batten frame and pressing upwards against the cups, are two set screws whose purpose is to raise or lower the cylinder.
(d) The cylinder. This is a square prism with a number of holes bored on each side to correspond with the needles in the machine. On each of the four sides of the cylinder and near each end there is a small brass peg (shown in Fig. [17]) for the purpose of holding the card in the correct position on the cylinder. (The perforations in the cards should be over the holes in the cylinder). The pegs are set so they can be adjusted to the right or left. At the ends of the cylinder square iron castings with rounded edges are fixed.
(e) A spring hammer, the flat end of which rests on the casting on the end of the cylinder. What might be termed the handle of the hammer passes through the lower cross rail of the bottom frames and through the top frame. A spring is placed between the two rails and around the handle of the hammer. The object of the hammer is to keep the cylinder perfectly level so that the cylinder will strike the board level.
Fig. 17. Spring Peg.
Fig. 18. Cylinder Out of True with Needle Board.
Flat springs also are attached to the inside of the batten, the lower end of the spring pressing the card to the cylinder. It is impossible to overestimate the value of these springs, especially on single cylinder machines, for it would be almost impossible to work without them. Their great value is shown when the cylinder is leaving the needle board by preventing the card from swinging on to the points of the needles, and also preventing the cards from slipping off the pegs as the cylinder is drawn over by the catch.