Quote Originally Posted by m_c View Post
How did you manage to preload the bearings if you only used grub screws?
The ER20 have threaded hole at the end (you may see it on web pics). I've just put another steel bush onto the shaft, put some load with screw pressing bearings towards each other. Truloc bounds within one hour, but I left it overnight. While I inserted a shaft seal on the coupling end, I left the other end without. The next day I filled spindle with oil leaving air gap that makes allowance for oil temperature expansion and then I put the seal on.
The only thing I would change is to replace the whole strait shaft chuck for tapered one. Of course I would then have to change the whole design: instead of unscrew chuck nut to replace tool I would replace the whole chuck with another one. That would make it a bit faster and there would be no need for Z axis resetting or at least I would know the offset. I'm not sure my lathe would handle bigger dia bars, definitely not my budget. It's quite exiting idea to try to produce this kind of spindle thou.