"Bob Engelhardt" wrote in message
news
On 5/16/2017 3:37 AM, Aussie wrote:
...
The sides of the cut are terrible, not smooth at all.
...

PVC and poor finish says "heat" to me. Try water as a coolant.

The photos appear to show that the bit deflected when the decreasing
rigidity of the parted-off end could no longer force it straight.