Page:Practical Treatise on Milling and Milling Machines.djvu/122

116 position. In these cases, washers should be employed. The following thicknesses are convenient: .001", .002", .004", .008", .016", and .032", as these give all steps from .001" to .032". The collars should be of uniform thickness, otherwise they are likely to spring an arbor when they are clamped up. Lead or Brass Hammer, and Brass Bar. Lead or brass hammers are useful to drive arbors or collets into the spindle, and seat work in a jig or vise. A steel hammer should not be used for these purposes, as it will mar pieces. Short lengths of gas piping with a cap on the protruding end make good handles for lead hammers. A bar of brass or copper, $3⁄4$ inch in diameter and five or six inches long, will also be found useful to place against end mills, or the end of small collets after the mills are in place. In this way the driving is often more conveniently done, and any hammer may be used.

TYPICAL MILLING OPERATIONS

In the illustrations of milling operations given upon the following pages, it should be understood that we have not attempted in every case to show how a job should be rigged up for commercial manufacturing, as special fixtures designed solely for certain operations are then employed. Our object is simply to show the novice how any number of jobs he is likely to meet with daily can be best set up. If it is a question of performing the same operation continuously, special fixtures, by use of which the work can be more conveniently and quickly handled, can be designed.