Civil Engineering Reference
In-Depth Information
the milling machine's column that allows the milling machine's head to move
in and out and often to rotate.) In this case, you leave the work in the same
position on the table and re-datum the work after moving the head on the ram.
Often, the ram can pivot to the left and to the right to access all areas of the
workpiece. If you are machining a large traction engine wheel rim on a tur-
ret milling machine where the head can swivel to the side, you can place the
wheel on the table so that the table is in the centre and completely surroun-
ded by the wheel.
Speed
The speeds required for milling will depend on the work you are doing, but
unless you are doing very fine work such as engraving, a maximum speed of
about 2,000rpm will be more than sufficient. A lot of the modern small mills
will have an electronic speed control, sometimes combined with a high/ low
gearbox. A Bridgeport milling machine will often have a two-speed motor as
well as back gear to reduce the speed. Another type of Bridgeport head has
a variable speed which is altered by turning a hand wheel.
