Can I use short rib bones alone to make beef stock?
A lot of the flavor comes from the marrow of the bone. Rib bones will need companion soup bones to help them. Alone, the flavor will seem weak or watered down. 
Now, if you are willing to put in the time.... Bake them first at 325f for an hour, let them cool and hit them with a hammer to crack them. you might want to cover them with a towel as not to send splinters about. This will allow the flavor to come out more during the reduction phase of the stock.