Review on Efficiently Tackle Hard Metal Projects With Aiyun'S 6-Pack Metric Drill Tap Set For Steel And Aluminum by Joshua Vogel

using the M6 bit to tap the extruded center holes on 2040 aluminum t-slot rails. successfully threaded 4 holes. mid way through the 5th hole I bent down to pick something up off the floor and bumped the tap handle. I didn't whack it with a sledge hammer or lean on it with my entire body weight. just gently bumped it with my well padded shoulder and the bit snapped. I was using cutting oil if that should make any difference. sorry about the poor image quality but you can see this product is definitely not made from HSS. it looks very much like pot metal.