Design of the Flywheel BY MILLING AND TURNING

The start of the machining, feature 2
Machining the spoke grooves, feature 3
The machining of the spoke holes, feature 4

The trepanning cut around the flywheel, feature 5 The next step was to
remove the work, clean off the chips and burrs protruding from the
surface, and remove the edge clamps. The blank workpiece now looked
like a pulley had sunken into it. The clamps were replaced on the left
side of the bar and the work flipped over on its y-axis so that the
filed notch was now on the lower right hand side. I loaded in the
g-code program for the bottom half ("flybot.cnc"), zeroed the x and
y-axis, this time to the right hand lower corner, then moved 2" to the
left for the x-axis and up again for the y-axis. In theory I was now at
the same 0,0 location as I was for the top half.

"The blank workpiece now looked like a pulley had sunken into it."
"The work flipped over on its y-axis."
I began the machining and had a small moment of self-doubt as I waited
for the program to start milling the spaces between the spokes. When
that operation started I was gratified to find that the spaces now went
clear through the flywheel and that I had located the edges correctly
and kept everything square. The machining continued until the profile
cycle finished it's last pass and the flywheel came free of it's
surrounding material. If I had used a vise it would have dropped down,
but as the groove was 3/16" wide the endmill just kicked it to the
side. Be careful when machining a part using this technique, sometimes
it will jam against the cutter and it will always put a small ding in
the side of the work, but in this case I was going to turn the OD so it
didn't matter.

"The spaces now went clear through the flywheel."
"The machining continued until the profile cycle finished it's last
pass." The flywheel, although rough on the periphery and bore and
needing copious deburring, looked just like I had imagined it. I
mounted the flywheel on my Taig lathe, drilled and reamed the ID to
5/16" and turned the OD. I polished up the rim and removed the
flywheel. I then spent some time deburring all the edges.

"Although rough on the periphery and bore and needing copious
deburring, looked just like I had imagined it."
"I mounted the flywheel on my Taig lathe, drilled and reamed..."
"...turned the OD..."

"I polished up the rim..." The finished flywheel looked as good as any I had machined from a casting.


This prototype flywheel showed me that it was certainly possible to
produce an interesting and aesthetically pleasing flywheel on my CNC
mill, and that with some more time spent on design and machining I
could produce almost any design I imagined. This strategy of milling
half of the design, mirroring the drawing, milling the other side,
trepanning and turning to final size could be used not only on
flywheels but on small wheels for R/C cars, train wheels and drivers,
or machine hand wheels. The project shows that while a simple flywheel
like this would be difficult to produce manually, CNC can reduce the
complexity and allow the unfettered design of beautiful small parts.