Plastic bobbin or quill

A quill of circular cross section for holding a supply of yarn wound thereon in overlapping layers having an elongated barrel and an enlarged butt end integral with said barrel, said butt end having spaced circumferential grooves provided thereon for accommodating retaining rings, said barrel being tapered from adjacent said butt toward the tip end thereof, the improvement comprising:

• said entire quill being molded of a mixture of a thermoplastic material susceptible to softening and melting at high temperatures and a blowing agent which generates a gas for forming a cellular plastic material having microscopic bubbles when heated above a predeterined temperature,
• said barrel having a solid portion extending from the tip end thereof towards said butt,
• a dense exterior hardened surface provided on said barrel and said butt,
• a less dense interior cellular core extending through said solid portion of said barrel characterized by said microscopic bubbles retained therein,
• an axial bore extending through said butt of said quill extending toward said tip and terminating in said barrel, said bore extending into said barrel a distance less than half the length of said barrel whereby said solid portion comprises the majority of the barrel,
• a dense interior hardened surface encompassing said axial bore,
• said dense exterior hardened surface and said dense interior hardened surface providing axial support which aids in maintaining dimensional stability thus avoiding warping.