Lathe turning finish help

[Ira]

I have a question about machining a shaft down to a diameter, sometimes I get a finish that's baby butt smooth, and sometime it's a little gritty, no matter how deep or shallow of a finishing cut. I use Tap magic cutting fluid and the carbide tip as shown. Should the cutter be dead parallel or slightly kicked in?

I got the Patriot dialed in so I can cut a diameter from the DRO measurement and the part matches exactly to the accuracy of my digital calipers. (after a final final pass). The inital finishing pass leaves the part about 0.001" oversized, and a second cut gets it right on the money. When writting a CNC program, how do you compensate for tool flex? Do you take a couple of redundant passes? Or, maybe I shouldn't be so anal, I'm not making dowel pins

[CountZero]

That looks like it could use some support from the tailstock. Might not cure all your problems but should reduce your workpice flexing.

[riverking]

try changing the tool, you are using a boreing bar. use a small rad tip to minimise push off.

[Ira]

The tool was set a little high, and the carbide tip was gouged or dull or something. It's a good thing I bought a box of ten tips on sale. I've been using this same cutter for everything and just changing its orientation for facing and spindle work; reverse turning gets me into facing mode.

I got a pretty good finish when I took a huge cut, cranking on the x-feed about as fast as possible (even using a dull tool), see first picture. But after I adjusted the height to a wisper below center, it cut smooth at slow feeds, and then after I played a little too rough and broke my cutter tip, the new carbide cut a very shiny surface. That's what I had seen before. The second picture is the part I was making. It's a small handle for the quill lock.

Thanks for the tips countzero and riverking, I'll try some new cutting tools, and try using the tailstock. I really want to do some drilling on the lathe, but I've been draging my heels, because I want to dial in the tailstock first. Yes, when I was little, I took the screws out of my toys before ever playing with them, drove my mom nuts.