Abstract: A retracting internal tube cutter for severing a tube from the interior is disclosed. The tube cutter includes a pair of swing arms mounted for pivotal outward displacement for effecting cutting of the tube. A retractor collar biased by a spring is mounted about the swing arms such that the collar maintains the swing arms in an insertion position except when the cutter is rotated. When the cutter is rotated the arms are forced outwardly causing the retractor collar to retract such that the cutter may sever the workpiece where desired. Upon discontinuance of rotation of the tube cutter, the retractor collar is urged into the insertion position withdrawing the cutter arms from the workpiece such that the tube cutter may be removed from the tube.

Abstract: The cutter blade and mandrel of a tube cutter coact through sloped surfaces having a tongue-and-groove connection. Relative axial movement between the mandrel and cutter blade causes the cutter blade to move radially inward or outward and the tongue-and-groove connection permits the mandrel and cutter blade to rotate as a unit to thereby increase the effective cutter height of the blade by the height of the underlying mandrel.