4- Flywheel and Crankwheel
The kinetic energy in the flywheel caries the engine through the
portion of its rotation where there is no energy input, therefore it
must have the necessary mass and geometry to perform this
function. Carefully consider materials when designing this
component. Steel and brass have about the same densities.
Aluminum is about one third the density of brass or steel. The cost
of brass is about three and a half times that of steel and about twice
the cost of aluminum per pound. Steel is significantly more difficult
to machine than brass or aluminum, especially when milling
features in the sides of the flywheel.
Machining the flywheel
Cut off stock with band saw, about 1/16” longer than
finish size, and face one side to cleanup in the lathe.
Setting up form tool
Set form tool for approximate diameter.
Cutting with form tool and applying cutting fluid
Slowly plunge tool to about half finished depth. Apply
cutting fluid as the tool is cutting. About 100 RPM would
be appropriate when making a 2” diameter 1018 steel
flywheel.
Cutting to full depth in at least two steps
Cut the first step to finish diameters. ( I.D. and O.D.) Cut
remaining steps just to meet and blend with the first
step.
Finished flywheel side relief
Parallel setup
Use parallels to make finished side parallel with chuck
face. You must put machine in neutral while using
parallels!!
Remove parallels before turning on machine!!!!!
Mill setup for drilling and tapping flywheel for set screw
Machining the crank wheel
Face crank wheel stock. Polish outer diameter and face
if desired. Break sharp edge with emery cloth or file.
When filing use slow speed.
Cut off crank wheel in band saw
Cut off part slightly longer than the finish size to allow
for finish cuts on the back face.
Setup for facing the crank wheel
Use parallels to position crank wheel in lathe chuck then
face to specified thickness, center drill, drill, and tap the
center hole. Caution! You must put the lathe spindle in
neutral while doing this!!! Also remove parallels prior to
spinning chuck!!! You should put the machine in neutral
whenever using the chuck wrench.
Setup for drilling and tapping holes in crank wheel
Drill and tap the hole for the piston bushing retaining
screw. Edge find the vise jaws, split the difference and
move to the centerline. Then edge find off one side of the
part and move to the hole location.
End