When I had a Smithy the best thing I found was a 3" 'screwless' grinding vise - I think I even got it from Smithy. My Smithy has been gone 20+ years, but I still have, and use, that vise. The vise that comes with a Smithy is junk - it's completely inadequate for milling and I can see a lot of people blaming themselves while it's the work walking all over the place.
GsT