Could someone point me to what i need please?

I’ve started making rings (for fingers!) as a hobby.
I have an Axminster 240 hobby lathe.
I can sculpt the outside of the rings easily enough by just mounting them on a tapered spindle.
What I need to be able to do it grip them externally so that I can work on the inside of the ring properly.
At the moment I’m just stuck with whatever diameter forstner bit I used to make the initial hole.
Every video I see on youtube shows people using (I think) Internal Safety Jaws to clamp around the ring so they can get at the inside.
And now for the question… I can find no details on this site, or anywhere else, about:

  • what size chuck / jaws I would need.
  • how wide I can open the mentioned jaws on a SK80 / SK100 chuck
  • if this is the right approach.
    Any ideas?
    I just need a secure way to hold a ring externally that will work with ring diameters up to around 3cm. Even a DIY approach is fine, so long as I can get the ring off and back on reliably centered.

The picture below is my ideal situation (but holding a wooden ring of course)

I think the SK80 has 12mm of travel on the mounting points, but that would only get me up to a 24mm object. Can I actually open the jaws slightly further safely?

Your picture shows an engineering, rather than a woodturning, chuck. If you consider that to be your ideal search for an engineering chuck with the correct mounting for your lathe.
You can get Internal Safety jaws to fit the Axminster range of chucks, so you have that possible solution.
Or you could use and Axminster chuck with other suitable jaws and/or make suitable jaws for the carriers.
Happy turning, Philip

You could try using a friction grip, mount a scrap block, turn a recess to fit the outside of your rings and push ‘friction’ fit the ring, this would also enable the ring to be reversed, to finish the other (what was the inside) surface.

I assume you have previously drilled the ring centres to aprox sizes.

Hope this makes sense to you. Barry

Apologies, I re-read my reply and your question:
I’d mount a scrap block in your jaws, and then hot glue or otherwise ‘stick’ the ring block to that, and use your the tail stock to hold whilst turning down to “outer size”. Then bore the finger size hole through just passed your ring width. Then once detached, use it, or another scrap block to turn a 'finger” spigot slightly tapered to slide the ring onto for finishing/polishing etc.
Hope this makes more sense. Barry