THERE ARE SOME POINTS TO ENSURE a good cut, we had many problems with the Rotary joint, we did some change in ours procedure taking the best practice for several procedure, here some Highligth in order to avoid dammage to the rotary
-Speed of rotation of rotary between 8 to 12 RPM,
-Cutting speed dropping between 3 to 4 ft / min (there are people that cut higher speed, which can generate the tool beaten the bed coke (these can lead to breaking some bearing inside the rotary) (actually this systems have a protection in order to avoid that)
-Cut the coke bands stripe between 3 to 5 feet,
-Cut from the tope to the bottom
Carlos if you read spanish I can send you some procedure, let me know, Best Regards