Howdy Tableau Tester,
The other option is to use parameters. Parameters have a built in ability to design your step size. The parameters can have sliders based on time and you can check with another calculation if your time is <= the big side and >= the small side.
There's also a much easier way to make your date calculation -
MAKEDATETIME(DATE([My Date]), MAKETIME(INT([My Date]),INT([TimeBin]),0))
I've attached a workbook and I hope it helps.
Date Example.twbx 19.9 KB
Unfortunately that's my old profile from a previous employer. But I can still get the emails and there was not a way to merge accounts.
Thanks for sending this my way though - was fun enough for a Sunday pre-football match.