Threaded rods can also be used to join planks. You need a drill bit long enough to drill through the width of the board, and a doweling jig is almost a necessity for boring straight holes. Drill the hole to a slightly larger diameter than that of the threaded rod. Rods should be at least ½-inch in diameter.
Mark the planks for drilling in the same way as shown for doweling. Use two threaded rods for any table of less than 5 feet; three rods for tables up to 8 feet. Where holes pierce outer edges of tabletop, drill larger holes (about 1-inch-diameter) to receive a washer, nut, and wooden plug.
When all holes are drilled, slide rods through planks to check fit. Also check the length of the rods – if too long, cut them with a hacksaw (leave room to fill edge holes with wooden plugs). Remove rods. Put a washer and nut on one end of each rod, then slide the rods through first end plank. Brush glue generously on the inner edge of the plank and slide second plank onto rods. Continue until all planks are together. Cap the rod at the last plank with a washer and nut, cinching it tight (you will probably need a socket wrench). Glue a wooden plug in the holes at the end of each rod.
Cut table ends when glue is dry, and sand the surface flat.
Cutting a Circular Tabletop
Cutting a circular tabletop is fairly easy using either hand or power tools.
To cut a disc from a single slab of hardwood or plywood, first scribe the circle with a pencil attached by a string or a wood strip (a yardstick will do) to a nail in the center. Cut along the line with a coping saw, saber saw, or band saw; or make a series of straight cuts with a handsaw or bench saw. If you use a saber saw, you can attach it to a wood strip nailed to the center and make your cut without having to scribe it first. Sand the edge smooth.
If you plan to cut a disc from doweled planks, it may be easier to assemble the top first without glue. Scribe the circle and mark the boards, then take it apart and cut the individual planks.
If you use a band saw to cut a very large plank top you will need to support the edge not resting on the saw table. Suspend the top from the ceiling by wire and turnbuckle attached to the center-point. If you wish, rest it on an auxiliary bench, or persuade a helper to hold it while you guide it past the blade.
Source by Protechwood