Nice work, it will be interesing to see how you get on.
Have you seen the "Diy spindle design" thread? It might be worth a read as I seem to remember he had an initial issue with putting to much preload on it and it got very hot. If you have it adjustable then you can get the balance between removing play and to much friction.....

I'm interested to see what you are going to drive it with? I have the Er11 spindle but not tried to power it yet. I've got a 100amp esc and Rc motor but not sure wether to belt or direct drive it?