My Bore has a taper ??

Any ideas guy? (and Gals)
when boring my bore diameter is coming out tapered.
check lots of stuff on the machine and everything seems ok.
when I bore 30mm to 60mm depth my bore comes out bigger, the deeper I go???
At first I thought it was boring bar deflection, but that would cause it to be smaller diameter, the deeper I go....
Any ideas???

How much taper? What lead-in angle on your tool? Tool could be digging in as it cuts. Could be misalignment of machine. Do you also get taper on OD? Could be part push off at a greater distance away from chuck. As the cut gets closer to the chuck it become more rigid.