The first of these seems like a simple enough idea. If you draw it, you might want to erase it. In order to erase an object, type in the command E and press return. It will now ask you to select an object to erase. In almost all editing commands, after you type in the command ACAD will ask for the objects to be modified. To pick them, simply click on the objects needing modification with the mouse and when you are done picking them press return. In the case of erase, it will immediately erase the objects selected. In older versions of ACAD if you use the pull down menus you will actually be using a slightly modified version of erase that doesn't give you the ability to pick multiple objects. It simply erases them after every pick. This can add greatly to the amount of time spent erasing, plus if you want to undo your command, you have to undo 20 erase commands rather than 1.
Fillet is one of the few editing commands that doesn't let you select multiple objects. It will only let you pick 2 objects that it will either trim or extend until they meet at a common point. To use this command, simply pick any two of the following: Line, Arc, Circle, Pline, Solids' surface edge, or Xlines. You cannot fillet Splines, Meshes, Polygons, etc. You also cannot fillet 2 Plines or 2 circles, but you can fillet a Pline to a line or arc. If you want to take the fillet command a step further you can also have ACAD place a specified radius arc between the two objects being filleted instead of simply joining them. To do this, after you type in the command and before you pick the objects use the subcommand R for radius then simply type in your radius amount and press return. Once you press you return, it will kick you back out to the command prompt. Press return again and it will take you back into the fillet command and you will notice if you read the command line area that it now is telling you the current radius amount for the fillet. Simply pick the two objects and ACAD will draw the arc for you. A few things to note about the Fillet command. In earlier versions of ACAD there was a bug if you try to fillet with a radius outside of the limits of the drawing it would sometimes not let you. Next, if you decide you want to stop filleting with an arc, redo the process above and for a radius value type 0 and press return.
