Cutter suction dredger.
https://s3-us-west-1.amazonaws.com/h...er_dredger.jpg
Previously:
https://www.homemadetools.net/forum/...892#post152638
https://www.homemadetools.net/forum/...363#post154504
Printable View
This is a huge ball end, through coolant, indexable end mill - except the coolant flows the other way!