trying to figure out where I'm going wrong...1 3/8" brass hex stock chucked up nicely in the lathe, need to bore a 7/8" x 3" deep hole. i center drill then progressively drill up to 1/2" and slightly shallow on the depth so i can finish later. everything good so far. i switch over to a small boring bar to open it up another 1/8" so i can switch to the 1/2" bar for the finish. The small bar leaves some ripples which i attribute to tool flex, but i figure the bigger bar will be stiffer and there shouldn't be a problem. However, with the bigger bar, the problem is remaining the same. i have lots of ripples, some as big as 3-4thou down the length of the bore. all combinations of fast/slow feed rate, fast/slow RPM, large/small cut seem to make no difference. the larger boring bar is a 1/2 kennametal with clean, sharp insert. Turning the outside diameter down results in clean, smooth finish.
I'm ripping my hair out on this. aluminum, steel, etc. seems to have the same effect.