Originally Posted by wschruba

There is a small margin of error, since the handles need to turn freely, but Park's frame tap/facing (by far the most common in US shops now...) tools are located by the threads. You thread in one side of the tool, slide the other half over the large guide, and start the other tap as you would any other bolt. As you turn in said side, it is being held in line with the already threaded side by the guide pin. It is an odd bike, that doesn't have some cutting done as you thread in the tap. Once both taps are in and about 1mm below the face of the shell, you withdraw one handle, place the facing cutter on, and slide the whole assembly back together. A few turns, and switch sides. It would be very difficult for the tool to cut out of plane, due to the design, but not impossible, as Andy notes. Misalignment on that order is okay...you're not prepping parts for a rocket, after all.