(1) Measure and mark a straight line on a selected surface. Have the exact length of the joists that will form the truss chord. This is baseline A (see Figure 3-31 ).

(2) From the center of the baseline and at right angles to it lay out the centerline (C) to form the leg of a right triangle, the base of which is at half the length of baseline A, and the hypotenuse of which (B) is the length of the rafter measured as indicated (see Figure 3-31 ).

(3) Nail 2- by 4- by 8-inch blocks flush with the ends of baseline A and centerline C as shown in Figure 3-31 . Mark the centerline on the center jig blocks.

(1) Start the assembly by setting a rafter in the jig with the plate cut fitted over the jig block at one end of the baseline. The peak is flush with the centerline on the peak jig block. Nail a holding block outside the rafter at point D as shown in Figure 3-31 .

(2) Lay one 2- by 4-inch joist or chord in place across the base blocks.

(3) Lay two 2- by 4-inch rafters in place over the joist.

(4) Center one end of 1- by 6-inch hanger under the rafter peak. Center the rafters against the peak block.

(5) Nail through the rafters into the hanger using six 8d nails.

(6) Line up one end of the chord.

(7) Nail through the rafter with 16d nails.

(8) Line up the other end of the chord.

(9) Nail as above.

(10) Center the bottom of the hangers on top of the chord and nail with 8d nails.