Thanks Arail,
Yes the CNC machine was doing the whole thing including groove on the outside rim. on top of that the dimensions for the wheel were requested to be changed a couple of times so it was a really difficult first model to do for CNC!! The spokes were separate to the rim. What I've learnt is as you say:
Keep things as clean and simple as possible
I was advised to increase the facets of any curves, segments or circles as high as possible
It might be an idea to draw in parallel projection as far as possible
I'm also thinking of upgrading to SU Pro8 from my current Pro7 as I was reading about creating outer shells. Maybe this would help?!
Thanks again for the advice!!