I have spent all morning trying to figure out how to add centerlines and other construction lines to my drawings without success.

For example I have some holes on a pulley I want to give angular dimensions to. Pretty much an identical situation to this tutorial.

At about 11 minutes he gives an angular dimension to two holes just like I want to do. I just can't figure out how to add the lines he is referencing in the middle of the circle.

http://www.canadianmanufacturing.com/design-engineering/cad-cam/applying-geometric-tolerances-in-draftsight-50588