Huge rock drill.
https://diqn32j8nouaz.cloudfront.net...rock_drill.jpg
Previously:
https://www.homemadetools.net/forum/...260#post141990
https://www.homemadetools.net/forum/...830#post129255
https://www.homemadetools.net/forum/...515#post155011
https://www.homemadetools.net/forum/...794#post124360
https://www.homemadetools.net/forum/...718#post147960
