The run-out on my mill is measuring about 0.1 mm, I've checked it with a few other tools I think I've narrowed it down to the taper inside the spindle.

I've cleaned out the spindle bearings and this improved things a tiny amount, but this is really stopping me from squaring the machine / head properly; this is also evident in the poor finish Im getting.

I've also found that the taper is only in contact with the lower 50% of the tool, is this going to be a contributing factor?

As I only have the Mill, my options are a bit limited, but Im currently thinking of getting a MT3 reamer to centre things up a bit, are there any other idas/ways to approach this problem?

Thanks in advance,
James