Profile: Tradex Instruments Ltd. specializes in precision gear cutting. Our products include bevel gears, gears, gear hobbing, spur gears, helical gears, worms/wheels and sprockets. We also provide CNC turning and swiss turning services. There are two types of spur gear the external spur gear and the internal spur gear. External spur gear teeth are used to provide a constant speed and torque relation between parallel shafts.