Using an M6 drill bit, successfully tapped 4 holes into the extruded center holes on 2040 aluminum T-slot rails. Halfway through the fifth hole, I bent down to pick something up off the ground and banged on the faucet handle. I didn't hit him with a sledgehammer or put my full weight on him. just hit him gently with his well-stuffed shoulder and the teeth broke. I used cutting oil if that matters. Apologies for the poor picture quality, but you can see that this product is definitely not made from high-speed steel. very similar to pot metal.