Right. Here I was thinking I had the answer. lol. I hadn’t remembered to consider the timing of when this flypress was made (which I haven’t really ever found any details for the years Denbigh actively made fly presses, and mine is a bit odd, in that it has a F. J. Edwards Ltd nameplate attached. But I could read and see the remnants of it saying “The Denbigh”, along with their logo or symbol just below the words on both sides. Perhaps this machine was a second, if they even did that sort of thing back in those days?), and the inch to metric changeover there. Man, to have been a fly on the wall, to know what all has transpired with this old piece of iron.We still used inches when that thing was made. Goodness knows what has happened since then with that sleeve insert.
Sounds like you will be drilling/tapping out the retaining bolt. ironically perhaps, that means you really will need to ream out the hole afterwards. If a tool galls its way into that hole, it will get stuck like it's been welded.
Good luck!
I certainly appreciate you driving home the reason why one would need to follow any operation that could/would create a remnant burr! I think opening up the sleeve, to allow the lock screw to physically contact the tooling shank, is an operation I hope to avoid. It feels like the end results might be fraught with peril. I will however, absolutely obtain a precision reamer, if I do go down that pathway.
Cheers
Lee