Got a long overdue mini-lathe on Friday. Checked runout using the supplied 3-jaw self-centering chuck and got some very disappointing readings until after fiddling discovered that one particular pinion when tightened resulted in runout typically 1/4 of that when tightened any other way. Even though results were now acceptable and repeatable I still though something was wrong with the chuck based on conventional wisdom which dictated tightening all pinions in turn. About to mark this pinion when I discover that it's already marked.
Searching Google on >lathe chuck runout< led to the term "master pinion" and an explanation but searching Google on >"master pinion"< returns only 4 relevant hits. Is there another name for this pinion? Is it common knowledge that there are 3-jaw chucks that operate this way? Can't find any mention of this on