Civil Engineering Reference
In-Depth Information
Fig. 1.20. This is a three-phase motor. The outwards appearance is no different to a
single-phase motor other than that many single-phase motors will have a capacitor to
make the motor run in the correct direction.
The column
The milling machine's column is usually a substantial iron casting, although
ground steel tubes have often been used as columns. There are two main
types of milling machine column: the round column and the dovetailed
column. The dovetailed column is usually quite substantial, and the head
does not move out of alignment when it is raised or lowered. The round
column however does not usually retain alignment when the head is raised or
lowered, and this means that you will have to reset the X and Y datums when
you raise or lower the head on a round column machine. The easiest way to
do this is with a wobbler and a wobbler extension. When you have the milling
machine head raised high, perhaps because you are drilling with a long drill,
you can use the wobbler in an extended adaptor, and when you lower the
milling machine head you can re-wobble the datum using a standard wobbler
without the extension.
