Depths of cut on a lathe

[M@T]

Just wondered how deep you guys make your cuts when machining billet bars for instance on a CNC lathe.

I use U2.5 which takes 5mm off overall but a mate at work used to test tips for SECO and reckons you can get away with 4-5mm per side which he uses all the time.

He scares me sometimes. He had to put a 45 degree internal angle inside a billet bar yesterday and came down from 60 to 45mm in one cut

[Rekd]

Originally posted by M@T Just wondered how deep you guys make your cuts when machining billet bars for instance on a CNC lathe. I use U2.5 which takes 5mm off overall but a mate at work used to test tips for SECO and reckons you can get away with 4-5mm per side which he uses all the time. He scares me sometimes. He had to put a 45 degree internal angle inside a billet bar yesterday and came down from 60 to 45mm in one cut

If you've got a good setup, it should work fine. (Just be ready with a new pair of shorts in case it lets go... )

I like people like your buddy. (Provided they know the machine's limits.. ) But you're right, there's a lot of 'pucker factor' there.

My brother in Penn does some serious hogging. If I can ever get him to post here, I'm sure he'd have some good stories to share.. *cough, KEVIN, cough*

'Rekd

[HuFlungDung]

Hi M@T
It depends what you've got for power available. Using a 38mm insert drill, at .1mm per rev takes all of 10 hp in steel, at 1500 rpm. Its not scary after an hour or two, because you have to feed it that way, there is no choice

But typically, I rough at 3 to 4 mm depth of cut in steel, or 10mm d.o.c in aluminum. Depends on the setup of the job, too. If its nice and secure, well nested in the chuck, I'll push it because it is safe to do so. Longer flimsy parts tend to bend on heavy cuts, and the machine begins a low frequency vibration that has a tendency to build on itself, and pushes the part through the chuck, or moves the tailstock back.

[mrainey]

Just depends,

We have a large Heyligenstaedt shaft lathe which, all day long, takes .400 (10mm) per side at .022 IPR (.56 MPR) in steel. You just have to have an appropriate combination of machine, tool, and setup.

[mach3magee]

Murphy's law
I ran hundreds of parts at .015ipr/.500doc
using a cnmg432 insert without a problem until one morning I showed up before anyone else and took the chip hopper out to the scrap bin while it was in the turning cycle. Long story short, the insert disentegrated and locked up the part. The real bad news came when I returned to the shop (which by then was full of smoke) and found that the spindle motor was still doing 650 rpm and $900 worth of drive belts were in a molten pool on the floor.
I backed off the depth of cut and got the rest of the day off so it wasnt all bad.