Abstract: A knife sharpener has a slotted casing for housing grinding wheels made up of modular elements placed in back-to-back relation to form an assembly interfitting with a second assembly. The two assemblies rotate in opposite directions for peripheral grinding. Plastic gears adhesively fastened to the wheels interconnect a high speed universal motor to the grinding wheels to effect a 3.55 speed reduction. Simultaneous hollow grinding is effected with a burr free edge.

Abstract: A portable grinder, honer and polishing machine is provided which has a horizontally rotating cylindrical grinding wheel continuously cleaned of swarf and wetted by a porous wiper extending into a liquid reservoir in the grinder housing. A tool rest with a phantom pivot point is pivotally and laterally movable relative to the grinding wheel and carries a tool guide protractor which permits accurate horizontal angular positioning of a tool being sharpened. A scissors blade guide is provided to precisely sharpen scissors and a retaining leg is pivotable into an operative position to hold the grinder stationary on a work surface. A tool stop is provided on the tool rest to ensure linearity of the sharpened edge on an elongated tool.

Abstract: An electronic charging circuit for battery operated appliances has a thermostat in physical, heat transferring contact with a battery pack to be charged, a power resistor in physical, heat transferring contact with the thermostat, the power resistor being connected in series with the battery charger and an electronically timed switch. Because certain types of fast charge batteries must be cooled after relatively rapid discharge, such batteries requiring approximately 10 times longer to reach full charge when overheated than when cooled, the electronically timed switch prevents commencement of charging of the battery pack after a rapid discharge until after the elapse of a selected amount of time sufficient to permit the battery pack to cool.

Abstract: A portable workbench including a pair of front legs and a pair of rear legs, with a support extending between the legs. A pair of beams extends laterally across the support and provides a work surface. The pair of beams and the support are adjustable to permit the beams to be positioned at a plurality of predetermined spacings relative to each other. Each of the beams has a plurality of spaced vertical axis apertures extending therethrough. A vise member having a mounting shaft extending therefrom which is proportioned to be received through one of the vertical apertures is also provided, the vise including a stationary jaw and a movable jaw together with a screw which extends between the stationary and the movable jaws for moving the movable jaw toward and away from the stationary jaw.

Abstract: An apparatus is provided for sharpening, grinding, polishing or honing metal objects which has a motor driven vertically mounted grinding wheel provided with a stream of water which can be recirculated to cool the grinding wheel. The device is provided with an adjustable guard to be mounted at the top of the device which has formed in it several guide means for use in sharpening various tools. A pivotable guard plate can be selectively locked throughout a range of angles with respect to the grinding wheel to provide an appropriate support surface. The guard can be adjusted upwardly and downwardly to accommodate wearing down of the grinding wheel and to adjust the grinding angle.

Abstract: A portable electric grinding tool for use in sharpening saw chains by means of a guide attachment attachably mounted at the sharpening end of the tool. The guide attachment consists of a detachable housing axially mounted on the tool having a separately detachable and reversible guide plate mounted parallel to the axial direction of the grinder rod displaced to either side of the axis of the grinder rod.