Machining > Milling > Square End Mills | Bordo Imperial Threaded HSS Cobalt Slot Drill - Short | Bordo Threaded HSS Cobalt Slot Drill - Short | Imperial. | HSS-Co8 (Cobalt) centre cutting, short threaded, square end. | Sometimes referred to as two flute end mills. | For general milling operations - creating slots and cavities. | Commonly used when milling steels and non-ferrous materials that produce large chips. | Fewer flutes are best for chip evacuation, keeping the bit cooler, but leave a rougher surface finish.