Call us on +44 (0) 1252 531444 (08707 700700)

  • Servo Grade Worm Drive Gearboxes

Direct Drive Theta (DDT)


Direct Drive Theta (DDT) rotary stage

DDT-100 DDT-200
Type Direct Drive Rotary
Bearing type
Preloaded duplex angular contact
Kingpost style angular contact
Motor type
3-phase brushless
Through hole
15 mm (0.59 in.)
50 mm (1.97 in.)

Accuracy (±arc-sec)Deviation from commanded angle.

12 6

Kinematic wobble (±arc-sec)Tilt of rotary axis irrespective of table flatness or physical runout of table top OD.

12 10

Kinematic radial runout (µm TIR)In-plane wander of rotational centerline irrespective of table roundness or physical runout of table top OD.


Table top parallelism to base (µm TIR)Total indicated worst-case parallelism top to bottom.


Table top physical runout (µm TIR)Total indicated runout of the top of the rotating table under stationary indicator at the table’s outer edge.

20 5
Repeatability Control Dependent, ±1 count possible
Resolution choices (includes index pulse)
1 µm, 0.5 µm, 0.2 µm, 0.1 µm
(75 mm ring)
1 µm, 0.5 µm, 0.2 µm, 0.1 µm
(200 mm ring)

Table resolution (KCPR)Measured in thousands of pulses per revolution of the table (KCPR).

236.8, 473.6, 1184, 2368 629.8, 1260, 3149, 6298

Speed limit (RPM)Note that maximum speed for ring encoder units decreases as resolution increases.

178-1273 66-477

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.


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.


Maximum moment (N-m)Moment loads are for L10 rating life of 1 million table revolutions.


Rotational inertia (kg-m2)Rotational inertia of table.

0.0005 0.0052 0.0051
Stage weight (kg, less motor) 1.5
3.6 4.5