Originally Posted by
John KJordan
Could thebit or bits be getting dull? If so, perhaps try a new bit. Some like thestandard grind, some like brad point.
It's important that the drill bit be perfectly aligned with the lathe axis,otherwise the bit can enter in the center then try to drill off at an angle, orenter off-axis, either can make the hole too big or cause the kind of vibrationyou mention. If the bit has some upward slant as you mentioned I think thatwould the first thing I'd try to solve. Might first check the morse tapersocket in the tailstock to see if there is any dust or buildup that needed tobe cleaned or a burr that is causing the jacobs chuck to not sit parallel tothe bed. If you have a dial indicator and can mount a piece of perfectlystraight drill rod in the chuck you could move and lock the tailstock down andsee if the rod is parallel to the bed. (The lathe bed must also be perfectlystraight.) JKJ