A plumb bob is made from steel, brass or lead. It's an old fashioned tool that uses gravity to help determine vertical alignment. Still in very popular use today, due to their simplicity and practicality, they are useful for straightening doorway frames, walls or any other vertical structure. They are exceptionally easy to use as well.
Step 1-Making Preparations
First, get the right plumb bob for the job. They come in many different sizes and weights for different applications. For typical home use, you will want to plumb bob which is between 4 and 10 ounces. To begin, cut a length of string that extends from the floor to the top of the surface whose alignment you want to check.
Step 2-Testing the Vertical Alignment
The plumb bob should then be attached to the string. The other end of the string should be attached to the ceiling or wherever it is level with the top of the vertical surface. The plumb bob should dangle down and because of its weight, it will be perfectly vertical. Because the plumb bob is hanging in a perfectly vertical line, you can use this as a reference to test the alignment of the surface.