Ball bearing turntable for 3wd crab drive

Hello, im building a3wd triangle crab drive platform and are in need for a ball bearing turn table with a hole in the middle ofminimum 10.5 mm. The size of it side * side should not be more than 50 mm * 50mm.

The problem is the smallest I have seen is 3" * 3"

And I have been searching around for a while now ( ebay, google) andcan't find any one of use so I was wondering if someone now where to get one,or how would you make one by yourself, without it falling apart when you liftit.

2 extra question)

First question: How much torque from a motor do you think it takes to turn the wheels when its not moving and lets say the weight is 30 kg, with thin plastic el scooter wheels?

Second question:
is 0.5 second for a 90 degree turn a good reaction speed or should it be faster/slower, for a more smooth drive (I know i'll play around with the turn speed, but if someone know or have experience with it, it will make it easier for me to design a gearratio, now its 30rpm for a 90 degree turn in 0.5 second.

i need pictures for this to make sense

first concept, haven't figurered out how to assemble it in real life?
Attachment 4333Attachment 4334


Second concept will be uploaded when im done.


And this is the type of wheel im using:

http://www.ebay.com/itm/NEW-200WATT-...item3a65bc4f97


here is a pic of the sketch for the platform:

Attachment 4335

its a non co axial swerve drive, like this:

Attachment 4336

scrap that. Just use an omni wheel and one of these

http://www.robotmarketplace.com/products/RL-OMX3.html

Far simpler to get an omni directional bot

im not interested in omni wheels, I like the swervedrive since its much more robust.

I'd disagree there but best of luck with the design

Thanks, I'll post again when I've more