Civil Engineering Reference
In-Depth Information
Fig. 2.11. Use an electrical test meter to check that your milling machine has a good
electrical earth connection from the earth pin of the plug through to any metal com-
ponents of the machine. (Note: this type of test meter is usually powered by a 9 volt
battery, so it is not suitable for electrical resistance checks as the insulation may not
break down until the test voltage is several hundred volts.)
Noise check
Next you need to run the milling machine in all its speeds from its slowest
speed to its fastest speed and in back gear if it has any. You are listening for
noise which indicates wear in the motor, belts, pulleys, spindle bearings and
gears. You may be able to live with a noisy machine but can your neighbours?
Axis wear
Next, turn the machine off and wind each axis to the ends of their travel. Is
there any wear? Do the slides feel loose in the middle and tight at the ends in-
dicating the table has worn unevenly? Some unscrupulous people have been
known to slacken the slides right off hoping that you will not notice the dove-
tail slide is worn in the middle.
