A technology capable of improving the accuracy of true-circular machining while avoiding an occurrence of intermittent cutting. A control unit of a machine tool determines an intermediate center position (Pi) in the moving direction for each divided rotation angle (E) smaller than a single rotation of the spindle and an intermediate eccentric radius (ri) around the intermediate center position (Pi) according to an initial position (Po) of the cutting edge in contact with the workpiece in the moving direction, the eccentric center position (Pc), and the eccentric radius (rc) to keep the cutting edge in contact with the workpiece as the moving object moves in the moving direction within a predetermined maximum feed speed (F) until a true-circular machining around the eccentric center position (Pc) is complete on the workpiece.

A hole expansion device includes a cutting portion main, body formed to have a diameter for the cutting portion, main body to be housed within a joint hole and including a cutting blade tool movable in a range from a housed position at which a blade is housed within a diameter for the cutting portion main body to an extended position at which the blade projects out of the diameter, an advancing and retracting member that is constructed to move in an axial direction by an external force and rotate about an axis of the advancing and retracting member, and a link mechanism that converts an advancing and retracting movement of the advancing and retracting member into a rotational movement of the cutting blade tool.

A hole expansion device includes a cutting portion main, body formed to have a diameter for the cutting portion, main body to be housed within a joint hole and including a cutting blade tool movable in a range from a housed position at which a blade is housed within a diameter for the cutting portion main body to an extended position at which the blade projects out of the diameter, an advancing and retracting member that is constructed to move in an axial direction by an external force and rotate about an axis of the advancing and retracting member, and a link mechanism that converts an advancing and retracting movement of the advancing and retracting member into a rotational movement of the cutting blade tool.

A cutting method in which, in cutting a circumferential face of a work, control is enabled to make a cutting velocity constant accurately by using a cutting tool projecting from a main shaft which turns around a predetermined position serving as a center and for which a turning radius is adjustable, wherein, in the case that a turning angular velocity of the main shaft is represented as , a distance from a turning center to a tip of the cutting tool is represented as R, and a cutting velocity of the tip of the cutting tool is set to a constant value C, making the cutting velocity of the cutting tool constant by performing control such that 0 changes in association with a change in the distance R so that
=(C.sup.2{dot over (R)}.sup.2).sup.1/2/R
is formulated (where {dot over (R)} denotes a time differential of the distance R), thus providing an even cut face.

A cutting method in which, in cutting a circumferential face of a work, control is enabled to make a cutting velocity constant accurately by using a cutting tool projecting from a main shaft which turns around a predetermined position serving as a center and for which a turning radius is adjustable, wherein, in the case that a turning angular velocity of the main shaft is represented as , a distance from a turning center to a tip of the cutting tool is represented as R, and a cutting velocity of the tip of the cutting tool is set to a constant value C, making the cutting velocity of the cutting tool constant by performing control such that 0 changes in association with a change in the distance R so that

=(C.sup.2{dot over (R)}.sup.2).sup.1/2/R

is formulated (where {dot over (R)} denotes a time differential of the distance R), thus providing an even cut face.

A cutting method in which, in cutting an inner circumferential face or an outer circumferential face of a work based on turning of a main shaft around a predetermined position serving as a center, control is enabled to make a cutting velocity constant. To achieve the object, a cutting method is provided for an inner circumferential face or an outer circumferential face of a work, using a cutting tool projecting from a main shaft which turns around a predetermined position serving as a center and for which a turning radius is adjustable, wherein, in the case that a turning angular velocity of the main shaft is represented as , a distance from a turning center to a tip of the cutting tool is represented as R, and a cutting velocity of the tip of the cutting tool is set to a constant value C, making the cutting velocity of the cutting tool is made constant by performing control such that changes in association with a change in the distance R so that

[00001]$={\left(C^2-{\stackrel{.}{R}}^2\right)}^{\frac{1}{2}}/R$

is formulated (where {dot over (R)} denotes a time differential of the distance R), thus providing an even cut face.

A hole expansion, forming device includes a cutting portion main, body formed to have a diameter for the cutting portion, main body to be housed within a joint hole and including a cutting blade tool movable in a range from a housed position at which a blade is housed within a diameter for the cutting portion main body to an extended position at which the blade projects out of the diameter, an advancing and retracting member that is constructed to move in an axial direction by an external force and rotate about an axis of the advancing and retracting member, and a link mechanism that converts an advancing and retracting movement of the advancing and retracting member into a rotational movement of the cutting blade tool, a tip portion bearing that is provided on a tip end of the cutting portion main body, and serves as a tip end side bearing when being housed in an inner side of the joint hole.

A router sled for woodworking. The router sled includes a router, a housing for holding the router, the router being slidably mounted to a rail. The rail being defined on a platform. The housing is slidably mounted to the rail. The housing slides with the router along the rail.

A router sled for woodworking. The router sled includes a router, a housing for holding the router, the router being slidably mounted to a rail. The rail being defined on a platform. The housing is slidably mounted to the rail. The housing slides with the router along the rail.