if using a lantern tool post , turn the rocker base upside down & shim if necessary to correct height ( center ) ..an openside block is even more ridgid ,which i now use.just a stud on a tnut /plate & a block w/cutr out for tool ..snug up the gibs ,particularly on light lathes....i ususally start w/ 1/2 or less normal sfm on late model craftsmn 12x36 .( cutting mild steel) ..if chattering does not stop as u start to seriously cut , drop the speed down ...& REMEMBER to feed in slowly at the reduced speed so u dont crowd the tool .....relief on front & sides ,as stated ,minimum overhang .,constant drip of dirtiest old engine oil i can scrounge for mild steel ( chip clearance is paramount ) ..if u cant get a stdy cut , u r most likely not on center /not sharp/no front clearance & it either wont cut or digs in ..... i use a slight top rake ground in w/ a large radius...cutting a V in the face of the bit helps tremendously ,minimizing chip clogging ,since u r not trying to dispose of a wide chip ( when u get to the point of v ,u r removing stock that has clearance around it ....) other helps in a deep cut are backing tool out & taking cuts on side of primary cut , to provide clearance..........there are other tool placements ( rear tool post , that some prefer)..
on the crftsmn , the power x feed is too fast for use , necessitating hand feed , at least for me ......
now after all that , a goosenck holder makes life a lot easier ....a shop made one on my 1895 14 in reed (1600 # ) is very forgiving ,since it will flex OUT of the cut rather than IN & a wreck...in fact i can turn a 60deg point on a one inch bar by plunging in a full width 3/8 flat bit w/out chatter at 140 rpm...it will flex down 1/8 in when needed, plainly visisble ...the armstrong gooseneck holders are not as flexible , but still forgiving ....
final thot is there is a serious learning curve on parting off ..each machine / operator has different parameters ( evidenced by posters using LOWEST speed possible & normal SFM , & neither of theses extremes comes close to suiting me )....
best wishes
docn8as