Originally Posted by
philbur
The diagram clearly shows open ends facing out, both top and bottom, as you would expect. So that leaves us with the advice 4Z7 received from the bearing technician - quote:
"My original bearings were installed both sets open end facing down and the technician told me that is how I should also install the new NSK bearings which I did".
I'm also curious about the rebuild quote 4Z7 received.
$100 to dismantle and inspect.
$300 for the 2 sets of bearings,
$3,000 for the complete rebuild.
That makes it look like $2,600 just to put the thing back together again, sounds odd to me.
Tormach will sell you a complete new spindle cartridge for $564. Of course you (or better still Tormach) may need to check the bearing orientation!!!!!
I would also question trying to squeeze 10,000 rpm out of this set-up. There is a compromise. Preload gives spindle rigidity, which is good. Preload with lots of rpm produces heat, which with this bearing arrangement would reduce the preload. The long "preloaded" length of this spindle design makes the preload sensitive to temperature changes. Finding a single preload setting that is equally good for the spindle grunting away “cold” at 500 rpm and running “hot” at 10,000 rpm might be quite difficult.
Maybe the answer is adjustable preload.
Phil