A. Brushes are fitted by cutting a strip of No. O sandpaper about the
width of the commutator surface. (Have the dynamo idle.) Place the strip
of sandpaper under the brush on the commutator with the rough side
towards the brush, then pull the sandpaper from right to left; continue
this process until the brush has been fitted to a true smooth bearing.
Then trim about one-eighth of an inch off the front edge of the brush.
45. Q. Is it advisable to ever try to fit a brush up with a file or
knife?
A. No.
46. Q. Why is it important to clean the scale off the point of the
copper electrode each trip?
A. To allow the point of the carbon and the electrode to touch to form a
circuit; this scale being a non-conductor of electricity and with it on,
the current would not pass from the carbon to the electrode and holder.