How to Make Ducts With Fibrous Board
- 1). Set a table saw blade at 11 3/4-inches from the fence to the blade. Raise the blade to 1-inch from the tip of the highest tooth to the point where the blade emerges from the table.
- 2). Cut the fibrous board into four pieces lengthwise on the table saw. Lay one strip perpendicular across a worktable so that both ends overhang the sides of the table. Run a bead of construction adhesive lengthwise along both sides of the strip 3/8-inches from the edge.
- 3). Stand up two strips on their edges on top of the glued edge, flush with the edge. Kneel down underneath the overhanging ends and shoot two staples straight up into all four corners, securing the sides to the bottom.
- 4). Run a bead of construction adhesive along both top edges. Place the last strip on top of the duct. Shoot two staples down through both corners to secure the top to the sides. Turn the duct parallel with the table and wrap circles four circles of duct tape evenly spaced around the duct. Pull the tape tight as possible with the tape. Glue should ooze out the cracks.
- 5). Shoot staples 2 inches apart down through the top and bottom the length of the duct. Run long strips of duct tape lengthwise along each edge to cover the points where the fibrous board is joined together. Wait 24 hours for the glue to dry before handling.