Machining sprockets in the third world - video

[Altair]

Machining sprockets in the third world.

Previously:

Assembling freewheel sprockets - GIF
Oxy-fuel cutting a sprocket - GIF
Cutting sprocket teeth - GIF
Waterjet cutting an aluminum sprocket - GIF
Induction heating sprocket teeth - GIF

[schuylergrace]

I have a yellow adjustable vernier micrometer just like his!

[metric_taper]

The way they tighten the 4 jaw chuck jaw screws, using a long pipe, I can see why the jaws are bell mouth loose, as seen in the beginning part of the video. He had several attempts at the raw steel disk falling out during his initial centering work.
The material looked very hard, so pre hardened heat treated steel. They showed him re-sharpening his trepan cutting tool at least three times, and on an open grinding wheel with no ability to control any angle, I guess that works for them.
I wish they would have had the camera zoomed out to see the horizontal machining of the roller chain teeth. I assume there was power feed. I don't know how concentric they mounted the wheels using inside calipers, but it must be close enough.