Turning 420 SS: NEED HELP

Hey Guys,

First off, Hello!

I have a Tormach 1100 and I am wanting to use it for some vertical lathe work. However, I am going to cut 420SS for the first time. I am getting these holders from MSC:

60064771

05697297

Any recommendations for inserts, holders (.5"), feeds and speeds, or anything else if very much appreciated. I also need a good recommendation for a cut-off tool.

I have basic lathe knowledge and not much more.

Thanks in advance!

Kyle

Kyle,

The 80° rhombus, and 35° insert styles look fine for ruff/ finishing applications.
For ruffing I would guess about 650SFM @ .01 IPR and .08" DOC, and 800SFM and .005IPR for finishing (surface requirement dependent)
I'd leave about .005" radially + the nose radius of the finishing tool on diameters for cleanup, and about .002-.003" on the faces.

For parting, I like Iscar GFN "*" J inserts for two reasons; (the * would be replaced with the MM width of the insert. I.E. GFN3J means a 3mm wide insert)
1) I'm used to their tooling and can predict what will and won't work.
2) they're available everywhere.

Here is the MSC# for the part-off holder: 60825163
IC354 grade should work great, and the "J" in the description means for softer materials like SS.
If this were a "Mod 420 SS" then I would use a normal GFN3 without the "J" chipbreaker.
Parting (setup dependent) would be about 500SFM @ .005IPR until I get within Ø.2", then I slow both the RPM and IPR down to not throw the part.

Doug.

Wow thanks Doug! What do you mean by "MOD" 420?

"MOD 420" is some of the nastiest stuff I have encountered. It is a a weird hardened 420SS that machines like crap!!