Cordless belt grinder. By Maciej Nowak Projects. 10:23 video:
https://www.youtube.com/watch?v=Sz4JnoeFUK4
Previously:
https://www.homemadetools.net/forum/...925#post175651
https://www.homemadetools.net/forum/...671#post174548
https://www.homemadetools.net/forum/...360#post173292
https://www.homemadetools.net/forum/...986#post171820