NO I'M NOT GETTING MARRIED :)
The title is to differentiate what I want from other kind of rings.

Yesterday I offered my wife to make a copy of her gold ring in titanium, I needed a project to improve my CNC lathe skills and it sounded good, so there I went.

The dimensions of the ring are: OD: 19mm ID:16.5 width: 4mm

So before starting in TI I decided to test in 7075 aluminium to anticipate and practice the difficult operations:

1) reduce diameter to 19mm - DONE
2) Make hole - Done
3) Bore to 16.5 - DONE
4) make inside diameter fillet - DONE
5) make outside diameter fillet - DONE
6) parting - DONE
7) use a collet to hold the piece and face it to 4mm width - DONE
8) make inside diameter fillet (the other side)- DONE

Here my problem begins, the collet needs about 2~3mm to grip the almost finished ring leaving almost no space to make the outside fillet, do you guys have an idea about how to hold the almost finished ring to make the final outside fillet?

My idea is to make a fixture with an expanding screw to hold the ring outside, with enough distance from the chuck to turn it. What do you think? Other completelly different methods for turning a ring are welcome too!

Thanks!


Pablo

Internal expanding arbor?

Dick Z

expanding screw ,internal expanding arbor - inside out collet or whatever yu might collet is nice and fancy ofcourse or just pressing it onto a nice piece of wood should give you just enough clamping since gold isn;t that hard and tolerances aren't that tight.
sandwiching between to slightly smaller diam pieces of anything softer like delrin or wood might work but would be less preferrable.

so i guess when tolerances are the matter a expanding arbor as the gentleman had pointed out or pressfit to a piece of conical wood when looks are the matter would be my 2pences.

just finished it, its exactly like this one (4mm wide): http://www.titaniumrings.com/stealthB.html

http://peu.net/mods/titaniumring-s

Ended using manual tools for the last operation :)