Rotary Positioning

ServoBelt™ Rotary Stage

High-precision rotary motion control in an easy-to-integrate package.

ServoBelt™ Rotary is a series of compact, high-torque motorized rotary stages that offer through hole size and speed comparable to direct-drive rotary tables costing thousands more.

  • Room in the Middle. ServoBelt Rotary stages offer two different through hole configurations. Available with 50-, 100- or 200-mm center openings, our large through hole stages accommodate large bundles of power, signal and pneumatic conductors. They also make it easy to integrate laser and optical systems. Standard-sized models with 16- or 25-mm through holes offer a more economical choice when fewer utilities need to pass through the center of the stage.
  • Direct Drive Performance. Designed for NEMA 23 and 34 motors, the ServoBelt rotary stages offer speeds up to 1,000 rpm, continuous torque to 6.6 N-m and resolution down to 0.16 arc-sec with Renishaw ring encoders or tape scales for partial rotation.
  • Application Flexibility. ServoBelt Rotary stages support both continuous rotation and variable indexing applications.
  • Robust, Lubed-for-Life Bearings. ServoBelt Rotary stages incorporate large full duplex, angular contact bearings, imparting moment and load capacities far in excess of its usual application requirements. This excess load capacity translates into virtually limitless bearing life.
  • Cost Effective. ServoBelt Rotary stages offer an economical solution for a variety of medium-duty rotary motion jobs such as driving carousel tables on packaging and assembly machines and providing fourth-axis rotary motion for laser cutting and mini CNC machines.

From gantry-mounted electromechanical assemblies, to cartesian robots with extended travel lengths, our engineered solutions are tailored to your needs. While our standalone stages must fit within a predefined physical space and tie into your machine’s motion control system, these larger turnkey systems free us up to optimize all aspects of assembly and controls integration.


SBR Through Hole Options

SBR Rotary stages with an extra-large through hole make it easy to pass power, signal, pneumatic, optical and other connections through the center of the stage. The large through hole also allows a tight integration between the positioning stage and related inspection, laser or robotic systems. SBR Rotary stages with standard-sized through holes offer a more economical choice when fewer utilities need to pass through the center of the stage.

Large Through Holes

For Easy Integration

Standard Through Holes

For Cost Savings

Custom Rotary Stages

While off-the-shelf rotary stages will do the job in most cases, sometimes your application requirements call for a customized ServoBelt Rotary stage. It may be something as simple as a special bolt-hole pattern on the top of the rotary stage. Or you may need a way to secure a workpiece in the stage’s center opening. Whatever your requirements, we can help. We’ve introduced accessories and modular design features that make it easy to customize our standard ServoBelt (SBR).

  • Collet Closer
  • SBR With Integrated Pneumatics
  • Three Jaw Chuck for Workholding Solutions

Customizations for the ServoBelt Rotary include:

  • Mounting Flexibility. Custom bolt-hole patterns and other machined mounting features are the simplest and most common stage customizations. We can modify the tops and mounting surfaces of all our SBR rotary stages.
  • Workholding Solutions. Often, the most difficult part of using a rotary stage is securing devices to the stage top for tasks such as inspection, laser marking or CNC cutting. We’ve introduced a new and growing line of workholding accessories that mount seamlessly into our rotary stages. These include air-actuated collet closers and three-jaw chucks to secure a variety of items.
  • Optimized Form Factor. Our standard stages are compact—both in profile and footprint. But sometimes you need a rotary positioning stage that has to fit in tight or oddly-shaped spaces. Our custom rotary positioning devices have met difficult space constraints on a variety of semiconductor, military and medical machines.
  • Challenging Environments. From vacuum systems to less-than-clean manufacturing processes, our rotary stages can be hardened and sealed to run reliably in environments that would shorten the life of an unprotected stage.
  • Drive Options. All of our ServoBelt rotary stages can be set up with third-party motors and controls of your choosing. Assistance with motor sizing is always available from our engineering team.
  • Extra Precision and Accuracy. For applications with the most stringent run-out and parallelism requirements, we can precision-machine tops of fully assembled, rotary stages. We often go through this extra manufacturing step for stages used in metrology or semiconductor manufacturing.

SBR Technical Specifications

Technical Specifications SBR-16-31 SBR-50-31 SBR-25-51 SBR-100-51 SBR-200
Type NEMA 23 3:1 Belt Drive Rotary NEMA 23 5:1 Belt Drive Rotary NEMA 23 or 34 11:1 Belt Drive Rotary
Bearing Type Preloaded duplex angular contact
Stage Diameter/Height (mm) 100/50 100/54 165/54 165/60.6 275/69.2
Through Hole 16.0 mm (0.63 in.) 50.8 mm (2.00 in.) 25.4 mm (1.00 in.) 101.6 mm (4.00 in.) 203.2 mm (8.00 in.)
Accuracy (±arc-sec)
Deviation from commanded angle.
16KCPR: 90
Ring: 36
16KCPR: 75
Ring: 48
16KCPR: 60
Ring: 66
Kinematic Wobble (±arc-sec)
Tilt of rotary axis irrespective of table flatness or physical run-out of table top.
8 16 10
Kinematic Radial Run-out (µm TIR)
In-plane wander of rotational centerline irrespective of table roundness or physical run-out of table top OD.
13 20 30
Table Top Parallelism to Base (µm TIR)
Total indicated worst-case parallelism top to bottom.
80 80 125
Bi-Directional Repeatability (±arc-sec)
With motor encoder versions only, assumes 0.2 degrees lost motion at pinion, divided by ratio.
16KCPR: 120
Ring: Control Dependent, 1 count possible
16KCPR: 40
Ring: Control Dependent, 1 count possible
16KCPR: 100
Ring: Control Dependent, 1 count possible
Uni-Directional Repeatability (±arc-sec)
Angular conversion of 10µm at bull gear radius.
16KCPR: 30
Ring: Control Dependent, 1 count possible
16KCPR: 12
Ring: Control Dependent, 1 count possible
16KCPR: 15
Ring: Control Dependent, 1 count possible
Resolution Choices 16k @ motor
Ring: 1μm, 0.5μm, 0.2μm, 0.1μm (100mm ring)
16k @ motor
Ring: 1μm, 0.5μm, 0.2μm, 0.1μm (150mm ring)
16k @ motor
Ring: 1μm, 0.5μm, 0.2μm, 0.1μm (225mm ring)
Table Resolution (KCPR)
Measured in thousands of pulses per revolution of the table (KCPR).
16KCPR: 48
Ring: 314.9, 629.8, 1574, 3149
16KCPR: 80
Ring: 472, 944, 236, 4720
16KCPR: 176
Ring: 800, 1600, 4000, 8000
Speed Limit (rpm)>
Note that maximum speed for ring encoder units decreases as resolution increases.
16KCPR: 1300
Ring: 1300-134
16KCPR: 800
Ring: 764-66
16KCPR: 360
Ring: 374-52
Continuous Torque, N-m (motor)
RMS torque allowed at table. Assume peak torque to be 3 times RMS torque for no longer than 3 seconds.
1.3(-1), 2.4(-2), 3.0(-3), 4.0(-4) 2.1(-1), 4.1(-2), 5.4(-3), 6.6(-4) NEMA 23: 9.0(-2), 11.9(-3), 14.5(-4)
NEMA 34: 20.0(-2), 30.0(-3), 38.0(-4)
Load Capacity Axial/Radial (kN)
Load capacity are for L10 rating life of 1 million table revolutions. Load capacity is not equivalent to payload. The ability to servo control a given payload is dependent on inertia, motion profile, duty cycle and control architecture.
14.0/26.0 7.0/4.0 48.0/39.0 14.0/8.0 21.0/12.0
Max. Moment (N-m)
Moment loads are for L10 rating life of 1 million table revolutions.
480 120 1150 434 1050
Rotational Inertia (kg-m2)
Rotational inertia of table.
16KCPR: 0.00048
Ring: 0.00093
16KCPR: 0.00051
Ring: 0.00096
16KCPR: 0.0033
Ring: 0.0050
16KCPR: 0.0060
Ring: 0.0070
16KCPR: 0.0037
Ring: 0.0046
Stage Weight (kg, less motor) 1.55 1.32 3.2 2.8 7.5
Recommended Payload Maximum (kg)
Bearing capacity is far in excess of these numbers for enhanced bearing life. Ability to control recommended payloads entirely dependent on move profile and moment of inertia.
10 252 100

Design Principles

ServoBelt Rotary stages embody design principles that ensure backlash-free operation and a long lifespan at high speeds about 1,200 rpm:

Duplex Angular Contact Bearings

 Duplex Angular Contact Bearings

ServoBelt Rotary stages are built around duplex angular contact bearings that can handle hundreds of pounds both statically and dynamically in the axial and radial directions, allowing the bearings to withstand combinations loads even when faced with tight wobble and run-out requirements. This design consists of two angular contact bearings whose faces have been precision ground so that the two bearings can function as one in a matched set. When clamped face to face within the rotary stage, the bearings have a preload that helps improve precision—by reducing backlash.

Backlash-Free Belt Drives

 Backlash-Free Belt Drives

All drive belts require some clearance between the tooth and mating groove to avoid interference when the belt is loaded. Excess clearance, however, results in backlash and loss of positioning accuracy. Our drive belts on our SBR 16, 25, 15, and 100 units feature a modified curvilinear tooth profile that minimizes the amount of clearance required between the belt teeth and grooves, reducing the potential for backlash. At the same time, this tooth profile has excellent load carrying capacity and smooth motion. Our large SBR 200 Rotary stage uses a trapezoidal tooth profile, owing to the larger loads these stages experience. While trapezoidal teeth usually require significant clearance, which results in backlash, our design eliminates clearance through tensioning at the motor pinion.

ServoBelt Rotary Applications

With its through hole, mounting and drive options, ServoBelt Rotary stages serve in a variety of applications, including:

Configure and CAD

© 2021 Bell-Everman, Inc.