A handheld dehider comprising: a housing; a pneumatic motor having an air inlet in the housing for providing a flow of pressurized air to the motor; a pair of cutting disks (32, 34) mounted in the housing, the cutting disks (32, 34) driven by the pneumatic motor; a speed governor in the housing between the air inlet and the motor, the speed governor controlling the flow of pressurized air from the air inlet to the motor; and an air pressure regulator disposed along the air inlet, the regulator having a valve to open and close flow of pressurized air in the air inlet, a bias spring urging the valve in the direction of air flow through the inlet to close the valve, a plunger operable to move the valve from a closed to an open position against the direction of air flow in the air inlet, a piston connected to the valve on one side and exposed to flow of air through the air inlet, and a regulator spring disposed between the piston and the plunger, whereby upon depressing the plunger the regulator spring urges the piston to open the valve against the air flow direction to permit pressurized air to flow through the regulator and on to the speed governor and the motor, and wherein during operation the sum of spring force of the bias spring and force exerted on the piston by flow of air through the valve is continuously offset by force of the regulator spring to maintain the degree of opening of the valve and wherein maximum pressure of the air through the regulator and subsequently through the speed governor is determined by spring forces of solely the bias and regulator springs and resistance of the piston to flow of air through the valve. a housing; a pneumatic motor having an air inlet in the housing for providing a flow of pressurized air to the motor; a pair of cutting disks (32, 34) mounted in the housing, the cutting disks (32, 34) driven by the pneumatic motor; a speed governor in the housing between the air inlet and the motor, the speed governor controlling the flow of pressurized air from the air inlet to the motor; and an air pressure regulator disposed along the air inlet, the regulator having a valve to open and close flow of pressurized air in the air inlet, a bias spring urging the valve in the direction of air flow through the inlet to close the valve, a plunger operable to move the valve from a closed to an open position against the direction of air flow in the air inlet, a piston connected to the valve on one side and exposed to flow of air through the air inlet, and a regulator spring disposed between the piston and the plunger, whereby upon depressing the plunger the regulator spring urges the piston to open the valve against the air flow direction to permit pressurized air to flow through the regulator and on to the speed governor and the motor, and wherein during operation the sum of spring force of the bias spring and force exerted on the piston by flow of air through the valve is continuously offset by force of the regulator spring to maintain the degree of opening of the valve and wherein maximum pressure of the air through the regulator and subsequently through the speed governor is determined by spring forces of solely the bias and regulator springs and resistance of the piston to flow of air through the valve.