While you might have some general working hours in your organization, some resources may not stick to those hours. You might have one person working a night shift, or someone else working four ten-hour days. Or, you might have a piece of equipment that runs nonstop. In Project, you can set a unique schedule for a specific resource.
Tip: You can also change resource availability without using a calendar.
Click Project > Properties > Change Working Time.
Note: Using Project 2007? Click Tools > Change Working Time.
Choose a resource from the For calendar list.
Choose the right Base calendar for the resource.
If the working times in the calendar aren't quite right for this resource, click the Work Weeks tab, and then click Details.
Note: What about vacation? Use the Exceptions tab to add vacation to the resource's schedule. Learn more.
Select the day(s) that you want to change the working times for, and then choose whether you want them to be working or nonworking time.
If you chose Set day(s) to these specific working times, use the From and To columns to set the working times for the selected days.
Click OK to return to the Change Working Time dialog box, and then click OK again.
What else can I do with calendars?
Project enables you to fine-tune scheduling using multiple calendars. If you understand how they all work together, it's easier to plan for how your project's dates will be impacted. Here are a few more articles you might find helpful in building a more accurate picture of the working and nonworking days in your organization.
Tip: If you don't need a calendar anymore, delete it!