Duro-M Manually operated self-centering chuck with a flat scroll and through-hole

It is primarily used on conventional lathes for machining parts through a chip-removal process. The chuck body is made entirely of steel and designed to ensure optimal accessibility, while maintaining reduced weight and mass inertia. A drip edge is integrated around its circumference for controlled coolant drainage.

Designed for use on horizontal and vertical conventional lathes, as well as milling machines, rotary tables, and dividing attachments, Duro-M is ideal for single-part or small-batch production, and toolmaking applications.

Application: clamping rotationally symmetrical components for turning and milling.
The base body of the Duro-M features distinctive scalloped surfaces. These reduce weight, making the chuck lighter. This weight reduction protects the spindle bearings of the lathe, allows higher acceleration due to lower inertia, and reduces energy consumption. The design also improves tool accessibility, following the principle that material which is not present cannot obstruct.

This space-saving benefit enhances the working area around the chuck, increasing operational comfort and efficiency.

The chuck body is made from a single solid piece to ensure high rigidity.
This monobloc construction avoids chip accumulation, ensures a clean appearance, and above all, provides the structural stiffness needed for maximum precision.

On the external perimeter, the drip edge ensures coolant flows off in a defined and controlled manner, minimizing splashing and improving cleanliness around the machine.

Duro-M offers one of the highest levels of force transmission among flat scroll chucks.
It requires less input force to achieve maximum clamping pressure, which is among the highest available. The design also allows for very fine and sensitive adjustments, ensuring consistent and precise clamping force. The efficient force transmission contributes to a lower overall height, freeing up space in the machine envelope and enabling better access. The reduced height also means less material and a lighter chuck, which saves energy and supports higher spindle speeds.

This outstanding performance is the result of precision-engineered German design.

At the heart of the chuck is the flat scroll, responsible for converting the torque from the chuck key into clamping force on the jaws. The shape of the toothing, the material selection, and the finish reflect Röhm’s decades of experience. The scrolls are hardened, tempered, balanced, and ground on both thread flanks for maximum performance.

Duro-M enables concentric clamping of rotationally symmetrical parts.
Clamping is achieved using jaws that are guided axially along the rotational axis by a precisely designed adjustment system. In flat scroll chucks like the Duro-M, the scroll ring performs this function. Spiral guideways are machined into its upper surface, and the lower parts of the jaws engage into these tracks. Rotating the scroll causes the jaws to move radially inward or outward, tightening or releasing the part.

The scroll is actuated by toothed pinions that mesh with the underside of the ring. The clamping key is inserted into one of these pinions and rotated, while locking screws keep the pinions in place.

The entire mechanism—including the drive and the scroll—is housed in the rigid one-piece chuck body. The rear is sealed with a cover plate secured by screws.

At the back of the chuck, a reference edge is integrated, enabling concentricity checks on the machine tool using a dial gauge.