Ace Designers Ltd. Offers Arm Drive Units. Ace Designers Ltd. Is an ISO 9001:2000 certified company. The Arm Drive Units are made in three basic sizes on the size of the globoidal cam. The smallest size Arm Drive Units can handle light weight tools [8 kg weight] and is suitable for 30 and 40 taper shank tools with small arm radius. The largest model can handle size of 50 shank tools of up to 30 kg weight. Three models of Arm Drive Units between themselves can handle most of the possible varieties of tools.