Carmex Carbide Tiny Tool - Small Threading ACME Tool - Grade BXC - 7.2mm Min Bore x Reach 22mm | Tiny Tool Inserts | Protool Ltd
HSS Threading Die Hole Diameter G1/2 inch For Water Pipe Screw Thread 1Pcs | eBay
Cored holes: Direct tapping with no tool breakage - Yamawa
Don't try threading holes freehand do it in a drill press or fixture. You MUST maintain EXACT coaxiality between the hole and the tap. : r/MarbleMachineX