A cutting tool includes a cutter disc, a cutter base adapted to be attached to an arbor, a fastener, and a plate. The cutter disc includes at least one cutting surface on each of a top and a bottom side thereof. The fastener extends through the cutter base and removably secures the cutter disc to the cutter base in each of a first position and a second position exposing a respective one of the top and bottom sides of the cutter disc for use. The plate is mounted to the cutter base between the cutter disc and the cutter base, and fixes a position of the fastener.

Provided is a spindle, a router device, and a cutting bit. The spindle may include: a spindle body having an internal space; a rotary shaft in the internal space, and having a receiving space configured to receive one end of a cutting bit, the cutting bit including a plurality of fastening portions spaced apart from each other in a longitudinal direction of the cutting bit and a plurality of cutting portions disposed between the plurality of fastening portions and configured to cut a substrate; and a support head at one end of the spindle body, and including a collet connected to one end of the rotary shaft and configured to selectively fasten at least one fastening portion among the plurality of fastening portions.

Provided is a spindle, a router device, and a cutting bit. The spindle may include: a spindle body having an internal space; a rotary shaft in the internal space, and having a receiving space configured to receive one end of a cutting bit, the cutting bit including a plurality of fastening portions spaced apart from each other in a longitudinal direction of the cutting bit and a plurality of cutting portions disposed between the plurality of fastening portions and configured to cut a substrate; and a support head at one end of the spindle body, and including a collet connected to one end of the rotary shaft and configured to selectively fasten at least one fastening portion among the plurality of fastening portions.