When burning out wound rotating elements? It has been our practice in the past when burning out the cores to do it by hand. What is everyone general practice on this? Associated Risks?

We approach the stripping of winding from rotating fields, with the exception of armatures, by putting them in our burn off oven. I notice you are standing by a synchronous motor. When we have to rewind the this type of field we remove the fields form the rotor and put them in the burn off oven. This type of field is normally rewound directly onto the field pole. The burn off oven makes for ease of data recovery, coil removal and cleaning of the pole-piece. With slip ring induction motors, after the slip-rings have been removed, the only risk is the shaft. Support the shaft as close to the core as possible. Keep the temperature at 650 degrees maximum and the integrity of the shaft will not be compromised. On occasion we have had difficulty in removing the slip-rings. This only happens when a previous repair shop has dipped and baked the rotor and decide that it would be a good idea to drop and bake the slip-rings also. Slip-rings and commutators should not be dipped except as a last resort. By last resort I mean that they will be replaced if ever the unit will require rewinding in the future. Slip rings should come off without too much difficulty, commutators are more difficult.
In the early days I was hesitant to take the burn-off approach, basically because on the shaft. Then I considered the fact that when there is welding done to a shaft, possibly attaching a spider for example, they require stress relieving which entails high temperature ovens. We gave it a try with some pressed out shafts and did not find any damage.
In the case of armatures, we do strip them by hand unless a new commutator is being installed.