Civil Engineering Reference
In-Depth Information
THE PARTS OF A MILL
The drive motor
As mentioned previously, an industrial machine's main motor can often work
from single or three-phase electrics. However, the majority of milling ma-
chinessoldspecificallyforhomeworkshopusewillhavesingle-phasemotors.
The spindle and head
The motor usually drives the spindle via a single drive belt with multi-step pul-
leys on the motor and spindle. Sometimes there is a gearbox between the
motor and spindle containing the back gear, which allows for a large reduction
in spindle speeds. Other machines may just contain a small reduction ratio to
reduce the speed a bit.
Some heads have a quill feed to the spindle so the spindle depth can be
wound up and down to set the Z height. Larger mills often have a power
down-feed to the quill for use when drilling, reaming and boring. These down-
feeds usually have a knock-off system so the down-feed stops automatically
when it reaches the stop.
