Use Polar Tracking and PolarSnap
 
 
 

To set polar tracking angles

  1. Click Tools menu Drafting Settings.At the Command prompt, enter dsettings.
  2. In the Drafting Settings dialog box, Polar Tracking tab, select Polar Tracking On.
  3. In the Increment Angle list, select the polar tracking angle.
  4. To set additional tracking angles, select Additional Angles. Click New. Enter the angle value in the text box.
  5. Under Polar Angle Measurement, specify whether polar tracking increments are based on the UCS or relative to the last object you created.
  6. Click OK.
 Command entry: DSETTINGS