Tapping in copper - Practical Machinist
03/06/2020The right tapping fluid can make a world of difference also.Was years ago,but if memory serves we used a flavor of Tap Magic. Also,COPPER FREAKING BLOWS to machine,I hate that gummy crap. 3/8" bus bar I run a spray mist on it and peck all the way out about every 2 diameters. Use a slightly larger hole if possible.