Belts or Balls getting me Screwed up! Help I need advice Please.

[JAZZCNC]

No need to get confuddled it's not rocket science really. The letters will correspond the Ballnut type. You just want standard flanged ballnut.

Regards dropping the diameter for Y axis then it won't affect setting up at all. What the larger diameter tends to do is reduce the acceleration and overall rapid speed you can tune the motors to, inertia and all that, but in practice with 10mm pitch and slaved 3Nm motors you have more than enough power in reserve and will still get perfectly acceptable feeds/accel that excede what you'll ever need for cutting. Whip is something you want to avoid at all costs and your in the region of where it can happen and for the little difference I won't take the risk.

Regards the Profiled linear rail and Ballscrews for that matter then Give Chai at lineramotionbearings a email with the sizes you need, give him total length of screws including the machining, ask for them machined and he will give you a price.
I don't think he shows profiled linear rails on his Ebay site but he does supply them, I've had loads of them now and they are fine.

I'll PM you his email.