Page:Practical Treatise on Milling and Milling Machines.djvu/41

Rh Oil Can or Pump and Tank. Every milling machine must be fitted with some arrangement for lubricating the cutters when working on steel, or wrought iron. Either an oil can or a pump and tank are employed for this purpose. For machines that are used for light work and miscellaneous milling, an oil can is found satisfactory, as the amount of lubricant used is small and a pump and tank complicate the machine and make more for the operator to care for. When heavy and manufacturing milling is being done, however, and an abundance of oil is required, both to cool the cutters and wash out ships, it is not always practical to supply it through the medium of a can, as this cannot be made large enough to hold sufficient lubricant to last long. By fitting the machine with a pump and a tank to which the used oil returns by gravity, a copious supply is available at all times. When it is not needed it can be shut off and a relief valve in the piping returns the unused oil to the tank.

No Exertion to Run the Table Back or Run it Up to Cut