TOOL HOLDER BALANCERS The BTI model THB-25 is the first spindleless balancer in the world. The new (Patented, US Patent Numbers 5,763,777 and 5,965,815) tool holder balancer is capable of exceeding ISO balance grade G-1.0. Typical tool holders today are standard sizes CAT-30, 35, 40, 50, as well as HSK. Historically, tool holder balancers have had difficulty achieving ISO balance grade G-2.5, and as machining center spindle speeds have continued to increase the task has become even harder. Customers are now requesting the ability of balancing to ISO G-1.0. Tighter balance grades equate to faster speeds and feeds, and therefore less machining time. BTI manufactures balancing equipment capable of balancing tool holders to this lower level. In the past tool holders were balanced by placing them into a mating conical adapter or directly in the shaft of the spindle, with or without a drawbar mechanism. There are numerous disadvantages to this method including the cost of a precision spindle, limits to the accuracy of centering the tool holder because of conical surface misalignment, and the added weight of the suspended balance spindle.