Abstract: A precision boring bar and a numerical control boring machine using the precision boring bar are provided. The precision boring bar includes a bar body having an inner chamber therein. The inner chamber is filled with a fluid medium which is not compressed. An active diaphragm assembly and a passive diaphragm assembly are provided at two ends of the bar body and communicate with the inner chamber. The passive diaphragm assembly includes a blade seat for selectively locking a blade. When the active diaphragm assembly is activated to press inward, the blade on the passive diaphragm assembly is driven synchronously to protrude. To cooperate with the program control of the numerical control boring machine, the blade will generate micro feed during processing for the inner hole of a workpiece to form a non-round hole.

Abstract: A musical door lock comprises a generally rectangular housing having enclosed therein door lock, an electric door bell and a battery chamber. When a push-button on the outer periphery is pressed to actuate a sound generator inside the housing, the combined electric door bell will release a musical melody or the sound of bird chirps inside the door. A second example provides a frequency regulator instead of a sound generator incorporated with a movable wireless door bell that offers more convenience to the house owners. In addition an anti-burglar device combine with the lock mechanism for releasing a warning signal which may be received by a portable radio receiver. This disclosure is characteristically providing an economical utility of space in a door lock as well as its variety of functions.