Thank you, Phill.
Do you mean the tapered octagonals or the octagonal "London pattern" handles? The latter are a favorite, but much more work than the ones that are simply turned.
The tapered (on both ends) octagonals were made with this jig (that works quite well):
View attachment 194945
I have found no faster way to make the London Pattern other than to:
1) Square stock.
2) Create octagonals on table saw or band saw.
3) Plane octagonals to smooth and accurately size.
4) Turn and fit ferrules.
5) Finish as desired.
Yes, I have literally hundreds of tangs. As I may have mentioned prior, I have a friend in Dawlish who regularly shipped me tools (prior to the postal regulation changes); many were just tangs.