Looking at the Axminster adapters there seems to be enough meat and quite a length of metal to adapt threads from one to another since each thread only needs to run 1/2 way through to work perfectly unlike metal lathes desperate to hold a through hole size. For pens using a mandrel its quite small. My problem out here is I use what was a standard 1 inch 10 threads for a few pieces of equipment before we went metric then I had an adapter made to enable me to use any of my Hercus metal lathe chucks on my Wood Lathes at
a University workshop. Anyone using a Taig lathe can buy real cheap threaded couplings that can be used for whatever you choose up in size one end from the 3/4 inch. I used a Vicmarc Adapter for my step up from the 1 inch to the Hercus thread as they are precision cut as I presume Axminsters Are same rule applies. Peter. I noticed the last comments I made while I was typing two or three others sent in answers looked like I was copying them partly, not so.
Kind regards, Peter.