BG Series goniometric cradles rotate on a transverse axis above the platform. Compared to full 360° rotation stages, they offer maximum free access to the rotating part and allow construction of very compact multi-axis rotation assemblies. BG cradles are designed so that orthogonal mounting of two adjacent-size cradles (e.g., BGS50 and BGS80) provides two perpendicular rotational axes intersecting at about the same point in space. Mounting a rotation stage under the assembly adds a third orthogonal rotation axis through the same point.Precision rotation is ensured by a precision ground, hardened worm gear drive. Single row ball bearings and precision ground tool-steel races ensure smooth rotation with minimal wobble and eccentricity. A home switch, conveniently located at the center of travel, facilitates the return of the platform to a level position.BG Series goniometric cradles are available in 5 sizes and may be configured with DC motors or stepper motors. The selection of the motorization is dependent on the application.
Stepper-motor-driven goniometers are available in a mini-step (PP) and full step (PE) versions. The PP mini-step drive version enables high angular speeds up to 20°/sec. The larger models BGM120PP to BGM200PP feature a worm mounted rotary encoder for improved accuracy and repeatability. The encoder also provides a method for detecting motor stalling, an important feature for applications with high loads or torques.The BGS50PP and BGS80PP are not equipped with an encoder and position is attained by the number of commanded steps or micro-steps. The high output torque of the stepper motor, combined with extensive performance tests, ensures position accuracy as long as the recommended load and torque are not exceeded. The BGS50PP and BGS80PP provide very high motion sensitivity with good linearity between commanded micro-steps and the actual motion of the stage. The PE full-step version with a reduction gear provides a higher torque and is recommended for high inertia payloads and vacuum applications. This version is available only on the BGM120 to BGM200 size.The DC-motor driven versions use three different motors and encoders depending on the size of the cradle. The BGS50CC uses a miniature DC servo motor with a motor mounted rotary encoder, a reduction gear and a belt drive in order to fold the motor. The result is a very small and lightweight package providing a very high resolution output and great minimum incremental motion capability. However, reversibility is compromised due to some backlash and hysteresis in the reduction gear and belt drive system.The BGS80CC features a high resolution 4,000 cts/rev rotary encoder with index pulse for precision homing and is the recommended choice for applications requiring accurate bi-directional positioning. For tightest position control, the rotary encoder is directly mounted on the worm screw. This avoids the majority of drive train error sources that affect other stages with indirect position read out. The BGM120CC to BGM200CC use high torque DC motors. This motor also features a built-in tachometer to provide superior speed stability.
For the definition of specifications see Motion Basics and Standards.
Motor cables are included.
1. Enhanced System Performance (ESP) Controller2. Compatible, but speed is reduced by 2.5x of the rated speed (ie, 40% of rated speed).3. Compatible, but MIM is 1/20th of a full step.4. For integrated stage and controller products, CONEX Integrated Rotation Stages and DC Controller.