Abstract: An over-temperature safety device is provided. A slug of material fusible at a selected critical temperature is positioned on a heat conductive surface. A bolt is positioned through a hole in the slug. The bolt has a head which is smaller than the bolt hole. A plate overlays the heat conductive surface with the slug therebetween. The plate has a hole through which the bolt head may pass. The plate hole, bolt and slug hole are coaxial. A compression spring urges the plate and the conductive surface together with less pressure than required to cause the slug to flow at temperatures below the critical temperature. The bolt is connected to a switch by an extension spring urging the bolt to pass through the holes in the plate and slug. When the slug melts, the bolt passes through the holes in the plate and the slug and opens the switch.

Abstract: A speed changing device wherein the driver and driven pulleys can be replaced to attain a desired increase or decrease in rotational speed. The distance between the driver and driven pulleys is adjustable so that the tension of the drive belt coupling the driver and driven pulleys is also adjustable. The mounting plate upon which the motor and driver pulley are mounted can be tightened securely against the housing so that the previously set tension can be retained during the operation of the speed changing device.

Abstract: A method and apparatus for cutting a hole with at most one line of symmetry in, for example, a sheet metal panel is disclosed wherein a plurality of holes are first drilled in the panel and thereafter a punch is positioned on one side of the panel and a die on the other side which are threadedly coupled together by a plurality of bolts passing through the panel holes so that tightening one or more of the bolts will draw the punch and die toward one another forming the desired hole. Typically, a central one of three bolts is tightened to perform the cutting operation while the remaining two are primarily for punch and die alignment purposes but may also be tightened to compensate for misalignment or when cutting a particularly heavy gauge sheet metal panel. Additional threaded holes in the die may be provided for threadedly ejecting a slug cut from a panel and additional punch supported pointed screws for center-punching the panel for a subsequent drilling operation may also be included.