Vertical shear finishing tool for the lathe - video

[Bony]

I use a set of tangential tools for really fine turning and as NortonDommi noted if you take the cut to the left with a right hand ground tool bit the finish is like a polished surface. If you use a round insert an extremely good finish can also be achieved, with the added benefit of many fresh cutting surfaces.

[tonyfoale]

In my own experience these vertical shear tools don’t do a good job of turning to a square shoulder. Am I expecting too much of this tool?

The cutting edge is set at an angle, so you cannot expect these tools to be good for a square shoulder. These tools are only meant for very fine finishing cuts.