turned on the face under the belt. A flat belt always tries to run on the highest place on the pulley; if there
is a crown in the center, making it the highest place, the belt will] run there and not need the flanges on
the sides. These are only to help if the belt stretches out of shape and one edge gets longer than the
other, in which case it will run to the side off the crown. When the belt starts to do this, discard it, as it
can start to whip at the high speed and cause vibration.
Make a pulley for the spindle, and a similar one for the motor, but fitted to the motor shaft. As these very
small mounted grinding wheels must run very fast, you may have to make several sets of pulleys to find
the maximum speed you can run it. This will be limited by the belt action.
Because of the high Speed required, it is not possible to use a belt of much weight, such as a "V" belt.
Such a belt would stand out away from the pulleys, due to centrifugal force, and would not only do very
little work but would be apt to start whipping. The small flat rubber belts, made for some floor polishing
machines, work very well at this speed. Since the total length of the belt is about 16 inches, you should
get one before making the base of the grinder.
Then, when the pulley diameters are known, the distance between pulley centers can be worked out.
This will govern the length of the 7/16-inch slot and the position of the bolt to the "T" slot of the compound
slide.
Make up two collars with parallel faces to grip the grinding wheel. After boring and reaming the hole,
mount them on a mandrel and finish both faces at the same setting. Use very light cuts so that the collars
will not slip on the mandrel. The face of the collar that bears on the grinding wheel is relieved so that
pressure on the wheel is concentrated well out on the wheel.
A layer of onionskin paper should be placed between wheel and collar to equalize the pressure. If the
collars are not relieved, one collar may put pressure on the wheel near the shaft while the other bears