[LongRat]

I can't view the video for some reason, but if it is a clattering sort of sound it is likely to be the quill splines rather than the gearbox. If you pull the quill down a bit and then check the noise and it goes away or changes significantly then that would be it.

[GusBiz]

try this for the video link

https://www.youtube.com/watch?v=yU7PD8AB-zM

[LongRat]

Hm, that doesn't sound like I was expecting. Most likely something else then. Just check it does the same thing with the quill lowered. If the sound goes away then it isn't a bearing problem I would suggest.

[GusBiz]

I have come to realise its actually some vibration in the drawbar. I changed the collet chuck and all of a sudden the noise was happening at a different RPM and yet it was consistent to that initial RPM while I only changed collets. More on this as I solve this.

[soltrold]

Hey

it is okay for the spindel to get 60-70´C
if you losen the upper nut to mutch is will result in bad finish,