A curtain assembly comprises a rotatable drive element wherein at least one helical guide structure is formed on, or into, the outer surface of the drive element. A drive attachment element having a structure that communicates with the helical guide structure to move the drive attachment element axially along the drive element when the drive element is rotated. Specific embodiments incorporate either a manual or motor-driven rotation assembly for rotating the drive element. Further specific embodiments involve a helical guide structure that comprises a helical groove and a structure that comprises a tooth that engages with the helical groove.

An apparatus is provided for lightening of thin, flexible and shaped workpieces by removal machining of material from surfaces thereof, on a machining unit having a worktable and a counterthrust member which rests against a part of the surface of the workpiece opposed to the one on which said tool must work from time to time. The worktable includes a support member of the workpiece to be machined, and gripping mechanism which supports the workpiece during its machining independently of the support mechanism. The counterthrust mechanism includes a board movable according to several axes and carrying a plurality of supporting elements. The supporting elements can be individually translated or in groups between a draw-in position and an extended position to define a supporting plane depending on the shape of the surface of the workpiece against which the counterthrust mechanism rests. A method is also provided for mapping the workpiece surface.

A lathe 1 includes a first tool rest 10 and a second tool rest 20 disposed to face each other with a spindle axis between them and is configured to, when machining a workpiece W with a tool attached to the first tool rest 10, support the portion to be machined of the workpiece W at a side opposite to the portion to be machined of the workpiece W with a support member 28 attached to the second tool rest 20. A servo motor 24 that moves the second tool rest 20 when supporting the workpiece W is supplied with a current within a preset limiting range. The limiting range is previously set based on a current value detected by driving the servo motor 24 to move the second tool rest 20 and detecting a value of a current supplied to the servo motor 24 during the movement.

A work material stabilizer for a lathe. The work material stabilizer comprises a center support bar having a predetermined opening from side to side and near one of the end pieces. The center support is detachedly affixed to a linear slide block and the linear slide block is detachedly affixed to a linear slide bar and the linear slide bar is detachedly affixed to a metal cutting bar. There is a bearing having a centered opening located in an opening in the center support bar.

Apparatus for working a sheet comprising movement means configured to move at least one sheet at a time in a direction of advance, and at least one working unit comprising a working head on which there are installed at least one working tool and a stabilizer device having opposite first gripping members and second gripping members facing each other, and reciprocally mobile along an axis of grip and release to tighten said sheet between them and to release it.