I would like to extract just the time component from a date/time column. I need the date/time column but for another column I need just the time portion of the date/time column. I cannot see a way to do this. The easiest way, in my opinion, is to allow computed column chaining (like formatting a lookup).
Is this just for display purposes? You can use a math column to redisplay an existing date column with formatting options to display just the time portion. The math formula could simply be date and you replace date with the column that contains your existing date and time. Underneath it will still contain the full date and time, but the formatting is unique to that column for display purposes.