Andrew,
Good point, hand facing tools are not that accurate and it's easy torque the cutters to one side or the other leaving an uneven surface.
The head tube and fork crown faces affect headset alignment and are more critical than the BB faces.
I've had to reface these surfaces a 2nd time because a headset wasn't properly aligning.
If the bores on the head tube are already to the correct size, it's easy to cut them oversize with the head tube facing tool.
I had someone make me a brass bushing to use in place of the head tube ID reamer on my VAR #32 facing tool to prevent this.
http://www.sheldonbrown.com/
Chas. Colerich Oakland, CA USA
Andrew R Stewart wrote:
>
> I have chased and faced the same frames two or three times over the
> years and each time the facing showed slight unevenness had existed
> before. Yet the same tools and techniques were used (I've owned my own
> Campy tool kit since 1980). I think I could repeat any number of times
> and still see a very slight change each time.
>
> Andrew R Stewart
> Rochester, NY