Abstract: An auxiliary device for use with vertical turning and boring machine tools having rotary work surfaces. The auxiliary device has a generally circular-shaped pallet and a support or mounting frame for supporting the pallet. The pallet has a hub for centering the pallet on a rotary work surface of a machine tool or for centering the pallet on the mounting frame. The pallet is fixed in such manner to the mounting frame that it can rotate with respect to the mounting frame and is fixed to the machine tool in such manner that it rotates with the rotary work surface. The pallet includes a plurality of radially extending openings which are engageable by clamping devices to position one or more workpieces in a desired position on the pallet. The mounting block has a central portion for supporting the hub of the pallet and radially extending arms having rollers engageable with a circular track positioned on the bottom surface of the pallet. One of the rollers is driven to rotate the pallet.