I made a set of thread chasers out of a set of old chrome bb cups. Take a dremel tool and cut 4 grooves in line with the bb axle direction and set a carriage bolt through it with the head inward. Set a pair of nuts on the end, tightened together to form a wrenching flat and voila, you have a thread chaser. I have used the same pair(you will need one for each side due to opposite threads) for several years. Be very generous about bolt torque.

Note: the parts list includes 1. a fender washer
2. A carriage head bolt
3. 3 Nuts