Teaching
Resources
Star Tool Grinder (STG)
Eberhard Bamberg, Ph.D. Massachusetts Institute of Technology, May 2000
My Ph.D. thesis at MIT, titled Principles of Rapid Machine Design, presents a set of principles used in the design and manufacturing of the Star Tool Grinder (STG), a CNC-controlled five-axis grinding machine used to manufacture endmills and similar workpieces. The machine has been designed for a loop stiffness of 50 N/microns and system modal frequency of above 35 Hz. Using the principles developed in this research project, the prototype of the STG was assembled in less than half the time required for the assembly of the existing machine, which is going to be replaced by the STG. A great success indeed!
The novel base of the machine consists mainly of two steel round tubes that are welded together to form a "T". The main beam of the gantry is made from a round tube as well and provides very high static stiffness. To ensure high dynamic stiffness, the round tube is equipped with a constrained-layer damping design called ShearDamper, an internal damping design.
Assembly of the bridge is simplified by replicating the assembly surface using a high-strength polymer. A thin O-ring between the bridge and base mounting surface creates a small gap between the two components. Three leveling screws are used to align the bridge with respect to the base, and once completed, moglice is injected through four spouts until the gap between the two mounting surfaces is completely filled. After the moglice is cured, the leveling screws are removed and the bolts around the joint tightened.
A complete presentation on the Rapid Machine Design can be found here.
