Hi mcm,
If you enter a Duration of 1 day, Project looks to the settings in
Tools/Options.../Calendar tab to see what a day means - 8 hours is the
default. So a 3 day task will span 3 8-hour days with the default Standard
calendar. If you now change to a 24-hour calendar, the task will now span a
single day - that's why the days change. I think you might be confusing
Work (the man-hours) with Duration ( the working time defined by the
calendar from start to finish). You might like to see FAQ Item: 5. Default
Working Hours
FAQs, companion products and other useful Project information can be seen at
this web address:
http://www.mvps.org/project/
Hope this helps - please let us know how you get on
Mike Glen
MS Project MVP
See
http://tinyurl.com/2xbhc for Project Tutorials