G02/G03 Synchronisation problem

I am trying to make a groove on a 340 Dia bar on a CNC lathe machine Lepond with Sinumerik 810T controller. The groove radius is 6.68mm and the sharp corner is rounded by 1.5mm radius. I use a button tool with 9.5mm (4.75radius) width. When I check the profile after machining, I found that the width of the groove is increased by around 0.25mm. But this is not uniform along the profile. I have NC program with nose radius compensated manually and without compensation generated using CAM software. Coordinates from the both method found ok. Compensation parameter like tool type and radius were entered on the machine.

I suspect synchronisation during the circular interpolation. Is there any method to check this?

Or is there anything should I check?

Please help.

Have you checked that your approach distance is enough to allow the control to initiate compensation?

Approach is distance is enough. I have program without nose radius compensation generated from CAM software. This program also follows the same path.

http://www.cnczone.com/forums/contro...ml#post1912818