About the Lathe Spindle End
Standards covering the lathe spindle end are stipulated in ISO, ASA, DIN, etc except JIS. Japan major lathe manufacturers manufacture the great majority of lathe spindle end parts at standards of JIS-A l, A2 (ISO-Al, A2). However, a part of lathe spindle end parts is manufactured at ASA-Al , A2.
Although the spindle end dimensions according to each standard are the same, the dimensional tolerance of a face plate (chuck or back plate) varies by a few microns.
Mounting the short taper (direct type) chuck for Spindle end.
The taper diameter of the short taper chuck for the spindle end is small slightly and the chuck has the some amount of interference (tolerance). A little gap occurs in mutual mounting end faces when the chuck is set. The chuck is closely touched by screwing mounting bolts. (The face having mounting bolt holes is the mounting face.) Tighten the chuck evenly by screwing bolts diagonally.
When interference (tolerance) of the chuck is large or small, any gap may occur in diameter direction. In the former case. the chuck may be deformed at the time of chuck mounting. In the latter case, a gripping accuracy becomes low for increasing a mounting error.
Similarly, the scroll chuck will also be deformed by tightening it excessively when mounting the chuck to the small end face of spindle end taper. Thus, the handle operation or chuck motion becomes heavy extremely.
Moreover, take care since the more interference, the more failure becomes large.
