Vivek,
The Martians, Team 494, lead engineer Jay Tenbrink has designed our robots with turrets for several years. We use a Kaydon bearing. It's mounted by it's outer and the inner race. We secure the bearings race with machined blocks that clamp it to the robot via a mounting plate and use the same block method to attach the arm or whatever the device may be to the other bearing race. It's hard for me to describe. A picture is worth a thousand words! See the publication that's out on robot design. You will find our robot featured in it with drawings of the turret. You can also contact us and we can advise you over the phone. PM me and I'll help out the best I can. Good luck.
Gene