A new project I did last week.
I bought a new bike to my daughter but the chainring was too tall (40 teeth) do ride it in trails near our house. I decided to try to machine a 32 teeth chainring.
First I did a mockup in plywood to make certain it would fit the bike chain.
Then I proceeded to fix the 150mm x 150mm x 6mm thick 6061 plate.
I first started by roughing the pockets:
Then brought the outer rim to 2.1mm thick:
Video:
For both I used adaptive clearing. (Climb cutting)
Cutter: Yonico 31011-SC 1/8 single flute
RPM:15000
DOC: 1.5mm (0.060'')Feed: 750mm/min (30 IPM) This gives a 0.05mm chip load. (0.002'')
Tool engagement: 0.07mm (0.030'')
Once the roughing was done I proceeded to finish the 0.5mm (0.020'') left by the roughing operation.
Video:
Cutter: Hydracarb 1/4 3 flutesRPM: 11 000 rpmDoc: Full depth (6 mm)Feed: 850mm/min (33 ipm) gives a 0.001 chip load. (0.0254mm)
The finish is better than what I hoped for:
My daughter asked me to engrave hearts in the ring. I did this using a carbide 6mm diam. 2 flutes 90deg cutter from china. I also used it to make a 0.5mm chamfer on all the corners.
Finally I fixed the chainring using a bolt in the center hole to cut the teeth contour without having to use tabs.
https://www.youtube.com/watch?v=lAjeY3_k6PY
Also used the Yonico single flute but dialed the DOC to 0.5mm (0.020'') since the tool was fully engaged.
The result is quite good. I took some measurements and most are below 0.003'' from my CAD model