How would I deal with this finishing issue on my Atlas Craftsman lathe?

[woodchucker]

Too me, it looks like you have a very sharp tool point, no radius and with a .004 feed rate, that's what mine would look like too.
But with a slight radius it would be smoother.
I don't see the need for a slower feed rate. If anything it's very slow. But in my opinion based on the look, that is too sharp a point on the cutter.

 

[MikeInOr]

I have made similar rough cuts on my lathe and they have all turned out to be user error (my errors). I think @woodchucker is correct that you need a tool with a slight radius on the end instead of a sharp point. Also make sure that the tool height is correct. I personally have solved many cut problems by setting the tool height correctly. It also looks like soft steel that is exasperating your problem. Is the tool tight? Is the tool extended too far from the tool post? Does the tool vibrate when cutting? Is the compound locked down tight? Try a completely different piece of steel from a different source when working out the issues.

I don't have the expertise of most on this board but I have completely mastered the art of making bad cuts with rough really bad finishes. RPM, feed speed, tool height, tool choice, the steel you are trying to cut, etc. all kind of have to come together.

 

[markba633csi]

It's just the feed rate I think. 4.8 thou isn't terribly fine compared to feeding by hand slowly
Mild steel also is prone to tearing when cut no matter the feed or speed

 

[GrifterGuru]

A couple of things here...

@woodchucker is on the right path with the tool nose radius. It appears to be too sharp. Great for fast roughing, bad for smooth finish which requires a bigger nose radius and you might want to check nose rake and top rake, that too can have a (smaller) effect on finish.

Is the tool chipped or burred? that also can cause poor finish. Is it just ground or have you honed it?

Also, get the tool tucked as far back into the toolpost / toolpost tool holder as much as possible to avoid flex/vibration.

Harmonic resonance can also be an issue at specific RPM & feed speed, sometimes exasperated by slightly loose gibs in cross slide, compound slide or carriage.

As to rigidity, you do not know flex and lack of rigidity until you try heavy turning on a 7x. Those things really teach you about what you need to know.