Apparatus for adjustably retaining an expendable medium for writing and/or drawing

An apparatus for adjustably retaining an expendable core for writing or drawing, said apparatus comprising:

• a tubular barrel having an outer barrel surface and an inner barrel surface;
• an elongated trough having an outer trough surface and an inner trough surface, the inner trough surface comprising spaced surface features, wherein the trough is immovably affixed along a portion of the inner barrel surface with the outer trough surface positioned in abutting engagement with the inner barrel surface;
• a follower positioned within the trough in abutting engagement with a portion of the inner trough surface, the follower having a helical surface feature corresponding with the spaced surface features of the trough such that the spaced surface features define a spiral path along the length of the trough for the follower, the follower having an aperture configured to receive a non-writing end of an expendable core;
• and
• a collet configured to rotate relative to the tubular barrel, the collet comprising a non-circular shaped passageway corresponding in shape to the expendable core such that the core can freely slide through the passageway along a longitudinal axis of the passageway but not rotate relative to the collet, and such that a writing end of the core protrudes from the passageway.

An apparatus for adjustably retaining an expendable core for writing or drawing, said apparatus comprising:

• a tubular barrel having a writing end and a non-writing end;
• a plurality of body members, each body member comprising:
• a head portion;
• a collar portion;
• a guide portion having an inner guide surface, the inner guide surface comprising spaced surface features;
• and
• a connection portion;
• an elongated cradle having an outer cradle surface, an inner cradle surface and cradle edges, wherein the outer cradle surface is configured to engage abuttingly with the inner guide surface of each of the plurality of body members;
• a plug coupled to the elongated cradle, the plug being configured to engage the connection portion of each of the plurality of body members, said engagement securing the plug and the plurality of body members together while permitting the plug to rotate about a longitudinal axis of the apparatus relative to the plurality of body members;
• and
• a follower positioned within the cradle in abutting engagement with the inner cradle surface, the follower having a helical surface feature corresponding to the spaced surface features of the inner guide surface of the plurality of body members such that the spaced surface features define a spiral path for the follower along the length of the apparatus, the follower having an aperture configured to receive a non-writing end of an expendable core, and the follower further having two contact surfaces corresponding with the cradle edges such that the follower rotates with the cradle when a respective one of the contact surfaces abuts a corresponding one of the cradle edges and torque is applied.