Attachment for pneumatic hammers for punching holes of varying size

An attachment for pneumatic hammers having reciprocatory internal hammer like drive means for driving a tool such as a hammer, chisel or the like, said attachment comprising a housing having means for supporting a tapered punch and adjustment means for limiting the effective length of travel of the punch exteriorly of the housing to vary the hole size in a work surface in which a hole is to be punched, said housing having an internally threaded rear end removably receivable upon an externally threaded muzzle end of said hammer, said tapered punch having a fixed axial travel within said housing, the housing having an axial opening defined by a forward barrel opening closely receiving said punch and an enlarged chamber opening having a forward boundary shoulder serving as a stop for said punch, said chamber opening having an axial length limiting the fixed reciprocal travel of the punch and said adjustment means having an axially adjustable stop means engageable with the work surface to be punched to limit selectively the travel of the punch in front of said stop means, said adjustment means being a tubular member slidably receiving the tapered punch and the tubular member being supported within said forward barrel opening on a muzzle portion of the housing in engageable relation with said work surface and axially adjustable with respect to said housing and a punch holder for said punch, said punch holder being slidably receivable within said housing and having a rear anvil end portion engageable by the drive means of said hammer and a forward end portion within said enlarged chamber receiving a rear end of said punch.