An employee was attempting to remove a grinding blade on a 4" grinder. He lifted the grinder and put it under his right arm to help him grip the tool. While grabbing the blade with his left hand and applying pressure, he inadvertently flipped the safety switch with the underside of his arm. The trigger then activated, causing the blade to move and suck his glove between the guard of the grinder. The blade then cut into his left index fingertip.