Motor shaft caulked within groove of eccentric load

A vibration generating device for a small wireless machine, comprising:

• an eccentric load portion;
• two side walls extending from said eccentric load portion, each of said two side walls having
• (i) an inner surface, such that a groove having an open end and a bottom is defined between said inner surface of one of said two side walls and said inner surface of the other of said two side walls,
• (ii) an outer surface,
• (iii) an end surface interconnecting said inner surface and said outer surface and positioned at a level relative to the bottom of said groove, said end surface having a first end and a second end, and
• (iv) a caulked portion extending into said groove from a location that is between said inner surface and said outer surface, and said caulked portion being positioned at a level that is closer to the bottom of said groove than is the level at which said end surface is positioned such that defined in said end surface is a recess which opens into said groove and does not extend completely across said end surface, whereby along an intersection of said end surface and said outer surface said end surface is continuos from said first end to said second end;
• and
• a motor shaft positioned within said groove between said caulked portion of each of said two side walls and the bottom of said groove.