Drilling holes in a coper is a pain.

And bigger pain is to cut the thread in it.

Copper is a viscous metal. And any spinning stuff can stuck in there.

I’ve spent a few hours to extract broken drills and thread taps from the plate. But now i have some experience. Expensive experience in case of time and labor costs.

Better to use some lubricants and take drills and thread taps off, while drilling just one hole, to clean them from shavings, multiple times.

And looks like extract small thread taps is almost impossible from fat copper plate without cutting it off with a part of metal around. So now i have some useless holes in the plate.