Incogs Lathe Bitch.

[Incogneeto]

Running a Haas 25 Lathe the material is the Prob .
1-7/8 0d. 1-3/8 ID. Steel Tube.
Boring at 1.445 =/- .001 5"deep SS 180 RPM F.005
1" boring Bar .
I'm only taking out .035 per side.
Have used .032 R. and .015R. Carbide Tin and AlTin coating.
 I get 5 parts per tip? Then it goes to Chit. Raucous Finish and sounds Terrible. Any increase on speed produces Chatter.
Have used M38 for Variable spindle adverse effect. Sloppy Finish. Any Suggestions??

[gcode]

Use 2 bars
One to rough, one to finish
And I`d try a higher rpm
You should be running 350 sfm in stainless
but your boring bar's L/D ratio is not ideal so 350 SFM may be too hot

[byte]

Running a Haas 25 Lathe the material is the Prob .
1-7/8 0d. 1-3/8 ID. Steel Tube.
Boring at 1.445 =/- .001 5"deep SS 180 RPM F.005
1" boring Bar .
I'm only taking out .035 per side.
Have used .032 R. and .015R. Carbide Tin and AlTin coating.
 I get 5 parts per tip? Then it goes to Chit. Raucous Finish and sounds Terrible. Any increase on speed produces Chatter.
Have used M38 for Variable spindle adverse effect. Sloppy Finish. Any Suggestions??

When you feed forward into the material the wear is concentrated on the tip of the tool.
Plunging in the x axis the cutting in reverse on the z axis can clear the chips and increase tool life, especially in shallow cuts.
This video demonstrates the concept fairly well.
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[byte]

Make sure the bushings are tight around the tube, even a little wiggle room can cause a lot of vibration, we would wrap tape around the raw material if it was loose.. I've seen loads of trouble due to a lazy setup.

[byte]

Some stainless steels have impurities that can wreak havoc on your tool, also if your inserts aren't good .005 per tooth can be too much.
Try .003 to .0035. What can I say shorten up your tool as much as possible, gcodes idea is about using 2 boring bars is a good one.

[byte]

You know... if you have 2

[byte]

If your setup is not very rigid you might have to actually go lower in your sfm, as counter intuitive as that sounds, if it sings turn it down,

[Incogneeto]

Thanks for the help. This pipe has what seems to be a casing O.D. and I.D. and it is just eating up These inserts. I'm getting maybe 5 parts per tip. 55 parts to do.

[byte]

In that case you should lower your sfm drastically, your first cut should ideally be deeper than the hardened layer..

[huskermcdoogle]

Negative clamp style insert or positive screw on insert?     Makes a big difference when you get towards 5xd.  

What brands and grades have you tried?

I'd possibly be looking at a solid carbide or tuned bar if you don't have one.  At the very least if you are holding the bar with set screws in a standard bushing, change to a split sleeve style holder and you may have better luck at that reach. If this is a tuned bar, higher cutting loads will usually solve vibration problems, either through feed or DOC if you are at the feed limit for material and insert, all you have is DOC to play with.  You need enough load to deflect the system for the damper to work.

Best of luck!  Happy to help if I can.

[Here's Johnny!]

Ultra-Dex makes solid carbide inserted bars.