Can you cut your dreads and keep them short?
Sure. You won't have to cut them very often because dreads gain length very slowly. The hair still grows the same speed but rather than adding directly to the length as it grows it winds around and around and knots so it takes a lot longer for the length to increase.
Cutting them is pretty easy; getting them to redread and not unravel at the ends is the tricky part. Before you cut them make sure there is really what you want to do!
Decide what length you want to cut them too - then cut them so they are about 1" longer than you'd like. This will give you some extra hair for making your new tips.
I would cut and finish each dread before proceeding to the next - that way you can make adjustments to your technique as you go if needed. Cutting is pretty final.
After you cut the first dread, leaving it an inch too long, use a dread comb to comb out the last inch so it's more flexible. You don't have to comb it out completely to straight hair, leave some knots behind.
As you comb much of the loose hair will come out. Don't be alarmed. Dreads are made of hair that is connected and hair that has shed. The loose shedded hair will comb right out.
Now insert a loose hair tool about 1" above the spot on the dread where it transitions from tight dread to partially combed out dread.
Slide the loose hair tool down the inside of the dread, right through the middle and push the tip of the tool out of the tip of the dread where the loose hair is.
Capture the loose hair in the latch and pull it up inside the dread. Just before you reach the point where you inserted the tool, stop and push the tool forward again and out through the side of the dread.
This will open the latch and drop the hair of inside the dread. Now close the latch and pull the tool all the way out.
This will leave you with a nice round tip that you won't have to work on. You can put a tight rubber band on it for a week or so to assist it in locking. Palmrolling the new tip will also help it lock together.
Now you can repeat these steps with the next dread. Fortunately dreads don't ever need to be cut and most people only trim them once every 5 years or so. =]