Page:Practical Treatise on Milling and Milling Machines.djvu/39

Rh and constructed that work and tools can be readily placed in position and removed from the table, spindle and table feed adjustments easily made, and all working parts readily accessible.

As the station of the operator is at the front of the machine, all controlling levers and hand-wheels for stopping and starting the machine and the different table movements should be within reach from this point.

The spindle speed and table feed changing levers of constant speed driven machines are placed on the left-hand side of the column by some builders, and on the right by others. This is more a matter of choice than anything else, the chief advantage being in having them conveniently grouped and so designed that the manner of operation is clear.

Arrangements for lubricating the various parts and making adjustments to compensate for wear should be such that these can be accomplished with a minimum loss of time.

Hand or Automatic Feed. It is essential that the table of all milling machines used for manufacturing purposes, with the exception of the very smallest of the plain type, be fitted with both hand and automatic feeds. In the case of this exception, the work done is of such a small character that the machine can be operated more rapidly by hand than it could be if an automatic feed were applied. By the use of automatic feeds, one operator is enabled to run several machines on the majority of commercial work.

Tool room machines, and those used for miscellaneous milling, should be fitted with both hand and automatic feeds, for, while much of the work requires careful feeding by hand, there are, nevertheless, many times when an automatic feed can be employed and the mechanic can devote his attention to some other detail of the job while a cut is being taken.

Power Fast Table Travel. On large machines it is necessary that the table be provided with a power fast travel in order that the minimum amount of time will be consumed in moving the work to and from the cutter.

Also a faster rate of travel is thereby provided than is possible by hand, and the operator is relieved of the laborious task of moving the heavy table and work many times a day. Both of these are points which materially influence increased production.