This turntable is the Goliath among the other tables which I had posted before:
viewtopic.php?f=6&t=2383
viewtopic.php?f=6&t=4291
It can withstand loads up to 200kg (per producer). But I never have tested the table with such high loads, only up to about 20kg. The (static) load is one thing, the other is that the mass also must be acceletated (against the inertia). Therefore I have implemented acceleration and deceleration ramps of the stepper motor speed.
The gear ring and its carrier ring are mounted together to one device. They are made of a very stable plastic. The upper ring is mechanically assisted by a lot of steel balls:
http://www.ebay.de/itm/Kugellenkkranz-L ... 43c73a7e13
The stepper motor with a planetary gear came from here:
http://nodna.de/nema-17-planetary-518-1-stepper-motor
The black plastic box for the motor is this:
http://www.conrad.de/ce/de/product/5384 ... 1GSBK-1-St
A cogwheel (it comes with the rings unit) is mounted at the gear's output shaft to drive the gear ring. An advantage is that the motor is lying horizontally, so the total height of the device is rather low.
Dimensions: Diameter of the platter: 280mm, overall height: 63mm.
Further specifications:
gear ring: 139 cogs
pinion: 24 cogs
gear ratio ( table gear ring / pinion): 5.79 / 1
gear ratio (motor / planetary gear): 5.1818 / 1
motor driver board: Pololu A4988 (¼ micro step mode)
platter: aluminium, 5mm thick
square plate: 300 x 300 mm, aluminium, 5mm thick
controller: Arduino Uno
power supply: 9V wall wart
Walter