A tube cutting apparatus of the type in which jaws carried by relative reciprocal slides move into and out of clamping engagement with tubing, the clamped tubing is thereof notched at its upper periphery with a scarfing blade, and the notched tubing is thereafter severed with a guillotine blade. The scarfing blade and the guillotine blade each are secured to their respective holders by a cam pin which coacts with a cam surface to bring an eccentric portion of the cam pin into wedging coaction with the blade in response to rotation of the pin and firmly and wedgingly secure the blade to its respective holder. The blade may be removed from the respective holder by simply rotating the cam pin a fraction of a revolution and then withdrawing the blade. A new or reground blade is replaced in the respective holder by simple insertion into the holder and rotation of the cam pin a fraction of a revolution in the opposite direction.