FWIW, the drill bit you used looks a lot like the bits used at McDonnell Douglas. When I first hired on and going through orientation the fellow in charge grabbed a handful of drill bits and put them in a piece of plastic conduit. He proceeded to bend the conduit breaking the drill bits and I never forgot the results. A lot of drill bits will just break in half under stress, these didn't. He dumped them out on the table and there were shards all over the place. The object was to convince us to always wear safety glasses and/or goggles and for me it struck home. Just a word to the wise. BTW, I have a container of those in varying sizes, all about a foot long.