When I fabricate site-built ridge vents like those described by Doug Amsbary (FHB #21, pp. 51-52), I use a jig to make quick and accurate 2x ridge-block assemblies. Once I know the pitch of the roof, I set my miter saw accordingly and cut the blocks for either side of the ridge. Then I face-nail a pair of these blocks all mated up to a firm flat surface, such as a plywood subfloor. This forms the bottom of the jig. Just above one leg of the pair, but well back, I nail two pieces of 2x scrap as shown in the drawing. These act as fences to help align the blocks and to hold them steady as I nail them together in the jig. A 16d nail driven straight through one block into the other on the outside corner and a toenail near the inside corner are all it takes to join the two blocks, and they’re ready for installation on the roof.
Jim Halls, Johnson, VT