Bench Grinder

Overview

A bench grinder is a fixed power tool that spins two abrasive wheels on a common motor shaft for sharpening, deburring, shaping and light stock removal. It bolts to a workbench rather than being handheld, so the operator brings the work to the wheel instead of the other way round. Mounting one coarse and one fine wheel lets a single machine rough a tool edge down and then finish it without changing wheels. This unit is a ½-HP, 150 mm machine running a capacitor-start induction motor at roughly 2,850 rpm.

Power enters through the Power Cord & Wiring and is controlled by the Switch & Control Board, whose large paddle switch and no-volt release keep the grinder from restarting on its own after a power cut. The Induction Motor is the heart of the tool: a single-phase induction motor with a double-ended arbor shaft that carries a wheel at each end. Both wheels are fully enclosed by a Wheel Guard, and an adjustable Adjustable Tool Rest in front of each wheel steadies the workpiece close to the abrasive face.

How it works

When the switch closes, the start capacitor inside the Induction Motor phase-shifts current through the auxiliary winding to develop starting torque; once the rotor is up to speed the motor runs on its main winding alone. The shaft spins both the Coarse Wheel Set and the Fine Wheel Set, each a vitrified aluminium-oxide wheel clamped between recessed flanges and held by a handed arbor nut so it cannot work loose against the cut.

The operator rests the tool on the platform and feeds it lightly into the spinning wheel; the abrasive grains shear away metal as heat and sparks. A Spark Deflector & Shield above each wheel deflects that spark stream downward and carries a flip-up clear shield, while a flexible Work Light illuminates the contact point. Because grinding heats thin edges quickly enough to ruin their temper, a Water Quench Pot bolted to the Base & Feet holds water for dipping the work between passes. The whole machine sits on a heavy cast base with rubber-isolated feet that soak up vibration so the wheels run true.