thanks Ross,
DIY Spindle design is one of my favourite threads.
Main difference is that he wanted high speed router at 20k rpm, my target is 5k rpm - my application is different.
My pre-load is not adjustable. It is set by the manufacturer of double-row, angular contact ball bearing that is used in the front.
If I was doing high speed spindle I would use the usual design of matched pair with adjustable pre-load, but I am hoping that at lower rpm I will get away with what I am proposing.