New to Project need some guidance

[Dryseals]

OK for the past few days I have tried to familiarize myself with MS Project, but I am not grasping a few things here and could use a push in the right direction.
I have a project that will take approx 12K man hours to complete. Its data entry so its a fixed amount of mhrs. Everyone is on a different schedule.
I set the project calendar for 12 hr work days, and then built individual calendars for the different shifts and assigned each person the correct shift calendar.
Everything seems to work fine with the exception of the duartion of the job.
What I want to do is to add in the total man hours (12K) and have it stay there add the resources to the task and see how many people I will need to complete this task within a give set time frame. But the duration of the task keeps changing. Can anyone help?

 

[johnherman]

Make sure your workday length is set to 8 or 12 hours as appropriate. Make your tasks fixed work, not fixed duration. Needless to say, save off a copy of the current plan before doing any of this.

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The trouble with doing something right the first time is that noboby appreciates how difficult it was.
- Steven Wright

 

[cosmicchris]

You didn't mention which version of project you're using. Previous guys advice is sound, but you're going to run into other problems too. Try working through the following book - Planning & Scheduling with MS Project by Paul E Harris. The book is divided into chapters with easy to follow exercises at the end. There are reference books available such as The Bible.. etc. but for usability quickly, Harris's book is the one.

 

[PDQBach]

There is one equation:
Work = Units * Duration.

There are three types of tasks:
Fixed Work
Fixed Units
Fixed Duration.

When you change a task there are three steps you must follow because of the equation:
1. Decide which you want to keep unchanged (work, units or duration)
2. Make the task that type (fixed work, fixed units or fixed duration)
3. Change one of the two remaining elements and the third element will change in an appropriate amount to keep the equation true.