I've not drilled a brass screw but have drilled a 1/16" hole through a 1/8" stainless steel screw a little over an inch long. The trick is to back the drill completely out of the hole about every 1/16" of an inch of cut otherwise the cuttings jam the hole and tragedy ensues. Use constant pressure when the drill is cutting and don't allow it to rub.

Pero

Stone the rake off the drill, withdraw regularly to claer swarf, use a collet as Andrew has said and drill dry.

regards Martin

Type of brass makes a huge difference to the ease with which the hole can be drilled, CZ121 will be easy to do while hard brasses can be difficult, just like some I had got from a steam rally stall.

Some weeks ago I made some small parts using 6mm OD brass, total length 20mm with a 1.6mm hole through, when drilling 1 of the pieces I could see something was wrong, the drill had run off centre and broken out through the wall at about 15mm depth but the drill did not break, needless to say I fitted a new drill.

Emgee

How did the screw break in half? Was it sticking out of the chuck? Sounds like workholding — or lack thereof– might be a contributing factor. Some kind of threaded collet that holds the job without crushing it hard enough to nip up on the drill could help.

You have about 40 thou wall thickness between hole and thread root so it should be do-able with suitable care.

Edited By Hopper on 24/07/2020 10:43:22

A commercial screw brass material will probably be tougher than the usual brass rod, so I would not back off the drill cutting edges with a stone, and then use coolant ,its a long hole and drill runing at high speed,the drill needs some lubrication on the flutes. My experience when at work was to turn brass dry on the fast plain bed lathes,and full flood soluble oil on the capstan lathes,the coolant kept the tools cool and flushed away the chips.