Need.........

[justplugit]

Slowing down the lathe speed has made a big difference. Thanks Eben.

[Raven]

in granite....requires some skill ....and if you don't constantly clear your bit....the bit either gets stuck or it walks from the chips...
getting 80 feet of drill steel stuck is a total bitch....let me tell ya..

so in and out slowly gaining a little depth each time is the trick.
wood is only different because its softer and once the bit walks
every plunge afterwards goes in that walked direction....
so its even more necessary to prevent it from walking to softer wood by clearing your cuttings ....sawdust or chips....