EDH0387En1020 — 09/18
2
BG Series Goniometric Cradles
2.0 —
Description
BG Series goniometric cradles rotate on a transverse axis above the
platform. Compared to full 360° rotation stages, they offer maximum
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-sized cradles (e.g., BGS50 and BGS80) provides
two perpendicular axes of rotation at about the same point in space.
Mounting a rotation stage under the assembly adds a third orthogonal
rotation axis through the same point.
Precise 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 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.
2.1
Design Details
Base Material
Stainless steel with aluminum body
Bearings
Ball bearings
Drive Mechanism
Ground worm gear
Worm Gear Ratio
BGS50, BGS80 and BGM120: 1:180
BGM160 and BGM200: 1:60
Reduction Gear
BGS50CC: 14:1, BGS50PP: 43:1, BGS80CC: 44:20
BGS80PP and BGM120
(1)
: None
BGM160
(1)
and BGM200
(1)
: 3:1
Feedback
BGS50CC: Motor mounted rotary encoder, 2,048 cts/rev
BGS50PP and BGS80PP: none
BGS80CC: Worm mounted rotary encoder with index pulse, 4,000 cts/rev
BGM120 to BGM200: Worm mounted rotary encoder with index pulse, 2000 cts/rev
Limit Switches
Mechanical, at ±45° (for BGS50 Mechanical, at ±30°)
Origin
Optical, at 0°
Cable
3 m long cable included
Vacuum Compatibility
Available up to 10
-6
hPa using full step motor (BGM120PE to BGM200PE only)
1)
Additional motor mounted 10:1 reduction gear with PE versions.
