Originally Posted by
idahoron
I think it is tool chatter. If you look at the pictures above that barrel is new never fired stored. The only thing ever sent down the tube was the camera.
You could be right Ron, but most modern processes are using TiCn (titanium carbonitrate) coated spade drills with "through coolant" capability for applications such as deep drilling. Possibly the spade insert needed to be changed and the operator ignored it or the programmer didn't add a few seconds of dwell in the program segment prior to retracting the drill once the final depth is reached. It's all about time and money with regard to manufacturing costs and they probably figure the average guy isn't gonna spend any money on something to look down his barrel with as long as it performs as expected.
BPS