Condenser printing - base chamfer in the wrong place

From issue #236 (closed), merge request !290 (merged) added a chamfer to the condenser so that if there is over extrusion and elephant's foot on the print bed it does not foul the fit to the dovetail.

The chamfer is taken at the bottom end of the dovetail - in the orientation when it is on the microscope. As the condenser is printed upside down, the chamfer is not on the build plate when printed.