A top can be threaded to a vessel with the Rose Engine. The threads on tail end of the spindle can be engaged with the thread follower to feed the spindle head assembly on its linear bearings into the thread cutter bit. A half round thread follower was used to allow engaging and disengaging the threading action. The threading follower is clamped in both the front and rear rubber clamps. The spring holds the threaded spindle against the thread follower. The follower assembly can be flipped over to allow thread engaging and disengaging for inside thread cutting also.
If any other threads are needed a threaded sleeve can be secured over the back end of the spindle and meshed with an appropriate thread follower.
The threading process would be much like cutting threads on a metal lathe. To engage the cutter at the same spot for each cut would require returning to the same rotational point for each successive cut. The position of an index hole number could be used as a starting point.