SECTION C - Assembly.

HEADERS.

The parts comprising each header are shown in figure 5. A thimble is forced open, a "C" ring threaded on, and the thimble closed; the wire is threaded through a sleeve, around the thimble and back into the sleeve until the bound end is almost at the bottom of the sleeve. The complete assembly is pulled tight, and in this position the sleeve is squashed fairly tight. Either end of the sleeve is then soldered, using a micro-bunsen burner and soft solder (60% lead, 40% tin.)

Figure 5

RUNG FIXING.

The rungs are threaded on two wires which have had headers assembled at one end of each. The first rung is placed in the slot of the rung spacing and fixing jig (described on page 3) having the rung stop, and the rung is spaced exactly five inches from the top inside curve of the "C" ring by using the header distance attachment described on page 5. This distance of exactly five inches ensures that, on joining two ladders together, there is no difference in distance between rungs at the join. The first rung is fixed in position by hammering a taper pin between the inside of the rung and the wire, care being taken not to damage the wire with the pin. (The effect of the pin is shown in figure 6.). Having fixed one side, the ladder is reversed in the jig so that the other end of the same rung is then against the rung stop, and the rung is then fixed to the other wire in a similar manner. The pins must be placed on the same side of the wire for each rung, with reversal of the side for succeeding rungs - this is done to prevent any curling and spiralling of the ladder due to the slight bend in the wire imparted by the taper pin. Having fixed the first rang, the ladder is moved up in the jig and the position of the second rung taken from the one already fixed. One rung is placed in each pair of slots, the wires pulled taut, and a pin driven in. For this operation it is advantageous to have two people working on the construction. Due to the rung stop fitted to the jig, it is necessary to reverse the ladder before hammering in the second pin, but this operation also cancels out any errors that may be present in the construction of the jig.

BOTTOM HEADERS.

Having fixed the last rung of the ladder, it is left in the jig and the bottom header assembled in the same manner as the top one. The correct position in relation to the bottom rung is obtained by using the header distance attachment. When the header is assembled in the correct position, it is pulled tight, the point where the cable left the sleeve being marked. The header is then disassembled and the wire cut at the mark made. It is then reassembled without using the jigs, pulled tight and squashed as mentioned in (1) above, and soldered, thus completing the ladder.

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