Lathe: what steel and cutter combo yields the best finish?

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spaceman_spiff

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I'm trying to keep this question as narrow as possible so the answer is as useful as possible.

Lets say the diameter is 1".

What steel alloy, and what kind of cutter geometry and material, will yield the smoothest finish?

And this is turning on a lathe.

Lets say we have 2000 rpm max, and 1/2 hp max, and we are dealing with rigidity in the realm of the cheapest lathes like an Atlas, but cutting either close to the spindle/chuck, or on a well supported between centers setup or with a follower.

And to any beginners reading this, if you attempt whatever is suggested, PLEASE POST PICS and describe how it went!!
 
Okay, I'll take a stab at answering my own question, and in a separate post so it doesnt get muddled up.

Things that make finish quality go up:

CUTTERS

Larger radius
Less stickout
Thicker tool


MATERIALS

Not sure...do free machining steels result in better finish or just easier machining?
Where in a given materials SFM range does a higher finish reside?
 
My Craftsman 109 1000 RPM (eye balling it) 1/6 HP lathe likes a Tangential tool with a small nose radius and maybe 10 degrees of back rake. I'm going to adapt a Derbyshire cross slide to it and will have to see what it likes then.

Don't laugh at 1/6hp, old 1/6hp motors are like 1/4hp motors of today. Never had the spindle on my lathe stall.
 
Andre said:
My Craftsman 109 1000 RPM (eye balling it) 1/6 HP lathe likes a Tangential tool with a small nose radius and maybe 10 degrees of back rake. I'm going to adapt a Derbyshire cross slide to it and will have to see what it likes then.

Don't laugh at 1/6hp, old 1/6hp motors are like 1/4hp motors of today. Never had the spindle on my lathe stall.
Click to expand...

what steel alloy, how did the finish look, and what were all the other details of the cut?
 
Okay a little more precision in the request..

If we are talking an atlas 10f..Id say our max rpm is probably 2000..maybe a little more..right? Not sure if it could actually be RUN higher..but I think with stock pulleys thats where you end up.

With a 1" part..thats 523 sfm...

This guy is getting mirror finish on 4130:

"Viper, Here's a quick video I shot last night. The work piece is 4140 3.75"dia it's a light finish cut with a Sandvik WNMG 432 WF (wiper) in their 5015 grade (cermet) at 975SFM. As you can see the finish looks ground. I can measure surface finish but it sure looks purdy. I uploaded it in 1080p HD so you can see how nice it looks."

If we want to do 975sfm thats more like 2" OD on our little Atlas.

http://www.youtube.com/watch?v=LRXjW3vGIVQ

So for your typical spindle bearing project..I think we need a tool bit that will work great at more like 500 sfm..not saying the above one wont, because I dont know..but it would be nice to find an example that does
 
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