A tool change unit includes a base and two tool arms rotatably mounted on the base and respectively located on two sides of the base. Each arm body includes a position-returning element, a gripping element, and an actuation element. The position-returning element enables the tool arm to rotate for upward and downward moving between a first position and a second position. The gripping element functions to grip a main-axle tool or a magazine tool. The tool change unit is combinable with a power unit to form a tool change device. The power unit drives the tool change unit to do rotation or rotation and upward and downward movement.

A tool change unit includes a base and two tool arms rotatably mounted on the base and respectively located on two sides of the base. Each arm body includes a position-returning element, a gripping element, and an actuation element. The position-returning element enables the tool arm to rotate for upward and downward moving between a first position and a second position. The gripping element functions to grip a main-axle tool or a magazine tool. The tool change unit is combinable with a power unit to form a tool change device. The power unit drives the tool change unit to do rotation or rotation and upward and downward movement.

A portable and field-adjustable milling machine comprises: a base; a milling assembly coupled to the base and that includes a milling tool rotatable by a driver; a roller bed coupled to the base and configured to support a tubular member thereon; and a vice assembly that is coupled to the base. Each vice member of the vice assembly is configured to be moved towards the other of the pair and includes camming surfaces configured to lift the tubular member off of the roller bed in response to the vice members being moved toward one another. The vice member may have a v-shaped notch defined by a pair of angled surfaces. The vice assembly lifts the tubular member and retains it in the notch at a position that is a predetermined distance away from the roller bed.

A portable and field-adjustable milling machine comprises: a base; a milling assembly coupled to the base and that includes a milling tool rotatable by a driver; a roller bed coupled to the base and configured to support a tubular member thereon; and a vice assembly that is coupled to the base. Each vice member of the vice assembly is configured to be moved towards the other of the pair and includes camming surfaces configured to lift the tubular member off of the roller bed in response to the vice members being moved toward one another. The vice member may have a v-shaped notch defined by a pair of angled surfaces. The vice assembly lifts the tubular member and retains it in the notch at a position that is a predetermined distance away from the roller bed.

A drilling and tapping machine includes a power head assembly supported at a vertical orientation, a parallelogram arm structure including a head support and an arm base, and an arm positioning assembly coupled with the head support and the arm base support for guiding corresponding movements of the head support and the arm base support so as to ensure a vertical trajectory of the power head assembly. The machine further includes a counterweight configuration to vertically move the power head assembly via a lever. The machine further includes an operational control assembly to selectively shift the power head assembly between a drilling operation and tapping operation. Therefore, the machine is suitable to make a hole with a diameter of 0.5 to 3 mm.