Hi Peter, yes you can engrave on a curved surface with a sprung loaded spindel. Ithink that if you look in the showcase forum, somebody has made a really nice version. I have a very old dahlgren engraver with this facility, but have not yet had time to make a new controller for it. If you do get a machine, it will probably need a fairly high Z clearance to accommodate whatever fixtures you need to hold your material ( I know that goes without saying, but Iv'e said it anyway). Goodluck. G.