Abstract: A fastener driving tool includes a housing defining a handle portion and a head portion with a nose portion extending therebelow. Mounted within the head portion is a cylindrical sleeve within which is reciprocally mounted a drive piston. A driver for driving fasteners is secured to the drive piston and reciprocates therewith. The tool includes a drive power control for controlling the penetration of the fasteners into a workpiece. The drive power control includes a choke encircling the sleeve to impede the flow of exhaust air from beneath the piston and under the sleeve during a driving stroke. The choke may be moved to a position spaced from the cylindrical sleeve wherein the flow of fluid below the piston is not inhibited. In addition, the tool includes a safety member with a workpiece engaging portion of at least one wear block secured thereto to engage the workpiece and protect the safety member from undue wear.

Abstract: A novel ink fountain comprises a fountain roller radially approached by an ink supporting doctor blade. In order to retain low viscosity inks in the fountain, the blade must approach very closely to the fountain roller surface without touching it. To accommodate the potentially irregular surface of fountain rollers, the blade is rendered transversely deflectable in segments by means of cut-outs, and vernier adjustment means acting on the segments may be used to conform the blade closely to the roller surface condition.