A spindle crank is considered an obsolete attachment in the United States because of its limited utility in production machining, however it can be a lifesaver in prototype or maintenance machining as it allows external threading to or between shoulders and to the bottom of a blind hole. It is essential where change gears are used to generate metric threads with an inch lead screw as the thread dial is no longer functional and the split nut must not be released.
The rectangular steel was generously donated by R & R sheet metal of Borger. The cylindrical steel was donated by a student's employer as salvage from a pump rebuild. The all-thread rod and SHCS were donated by N.B.S. of Borger. The crank was designed and manufactured by our machining students over two terms.
The crank tightly grips the inside of the lathe spindle when the arbor expands when tightening the nut causes the sections of the arbor to shift sideways. The front part of the arbor is threaded and the all-thread rod is retained by the jam nut. The back part of the arbor, welded to the crank handle is drilled such that the all-thread is a sliding fit with enough room to move sideways slightly.
This view shows the spindle crank installed in operating position on an Emco Compact 10 lathe. When the nut visible in this view is tightened, the crank is firmly clamped in the spindle. The back portion of the spindle was welded to the crank arm at no cost by the welders of an employer of one of our students.
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last updated by GmcD on 27-May-14 14:59
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