Page:Practical Treatise on Milling and Milling Machines.djvu/115

Rh example of the use of arm braces that extend from the knee to the overhanging arm and carry the bronze bushing for the outer end of the arbor is shown at C. These braces firmly tie the knee and overhanging arm together, and give a stiff support for the arbor. They should be used whenever the character of the work is heavy. This illustration also shows the use of an arbor yoke for stiffening the arbor between the cutters. This yoke should be used to bring a bearing either between or as near to the cutters as possible.

Fig. 58

Before tightening or loosening the arbor nut, when putting on or removing cutters, be sure the arbor support is in position, so that a bearing is provided near the nut, otherwise the arbor is liable to spring.

Clamping Work. An operator should pay particular attention to clamping work on a milling machine, for the success of milling is more dependent on this than on would realize at first thought. It is an easy matter to place clamps on some work in such positions that the piece is sprung, consequently when the clamps are loosened and the piece resumes its natural shape, the milled surface is found inaccurate. Again, faulty clamping results in work becoming loosened during operation, and not only impairs the accuracy of the piece, but many