ArcEuro do some soft end arbors....,you could machine one of them to suit your face mill bore, then drill and tap the end of the arbor to retain the cutter.....ok it won't be keyed to the shaft, but that has to be better than jammed cutter/burnt out motor/stripped gear teeth.....
How about these?
060-300-00600 or 060-281-00322 on offer at ArcEuro.....?
Any good?