Clamping nut - ER11 collet... am I being thick?...

[Doddy]

Okay, I've finally got a 800W chinese spindle mounted, finished wiring, plumbing in coolant, decided to try it for the first time and the drill bit was obviously off-kilter (tracing a nice 2 mm diameter arc on rotation). So, I tried reseating it again and again, no joy, but what I noticed was with the clamping nut released the bit spun normally, and it was the action of tightening the nut that offset the drop of the bit.

Anyway, looking down into the internal thread of the nut, something seems amiss - see photo.



Before I try to source a replacement, am I being thick, or is this the Chinese at their best, unable to bore a hole centrally?


Mike