Flow friction drilling.
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Previously:
https://www.homemadetools.net/forum/...455#post142764
https://www.homemadetools.net/forum/...2814#post97209
https://www.homemadetools.net/forum/...7862#post86386
https://www.homemadetools.net/forum/...794#post124360
https://www.homemadetools.net/forum/...534#post110853