Y axis Drift in rotary carving

[Baron Richard]

I did my first rotary carving yesterday, and almost everything came out the way I expected except for the left-right meeting on the "back" of the carving.

Here is the design file in Project Designer 2.007 build 11929
Front

and back


and here is how it carved:

The front is fine, 180 degrees through the carving, its when it gets to the wrapped portion that the carving shows the Y axis drifted as it turned on the X axis:

any suggestions on what could have caused this?

Richard