# I Hate 304 Stainless!



## rake60 (Jul 22, 2008)

I've cut 304 Stainless Steel at home.
It's a real challenge on small machines because it work hardens easily.
Sometimes it feels like your not really cutting it, your just making it MAD! :big:

At work today I started a run of 1/2" thick disks that are made from 3 1/2" Dia 
304 bar stock. There will be 24 of them all totaled.
On piece #8 the insert in the parting tool gave out.
From the time I heard the click of the insert breaking until I hit the feed hold button,
(maybe 1.5 seconds) the blade of the parting tool was toast.

Only 16 pieces to go.
We'll give it hell tomorrow!

As for cutting it at home in the near future.
I'm thinking *NOT!*

So who does cut 304 at home?
What are your methods?

Rick


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## shred (Jul 22, 2008)

I've only ever done some bits from 303 and those mostly look like they were gnawed out by mice.


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## BobWarfield (Jul 22, 2008)

I had to drill some holes in some 304 plate in welding class on the drill press. I was looking at it with some trepidation having burned up a drill bit at home doing the same. I asked the instructor about it and he said get you speed right and feed it hard. Don't try to take light cuts because you have to get through the work hardening as fast as you can. Don't hesitate and don't back off.

He was exactly right, and it worked great on the drill press.

I had a similar experience on the lathe and used the same tactics. It was definitely no fun. I laid in some 303 stock just to make sure I wouldn't have to deal with 304 much.

I'm sure you've heard the machinist's expression:

"304, she's a <not very nice lady rhyming with OAR>, 303, that's for me!"

Cheers,

BW


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## zeusrekning (Jul 23, 2008)

Yeah what BW said. Low SFM and higher feeds.


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## machinist dave (Mar 6, 2009)

304 and 316 ss wants sharp tools, slow speed and coolant.it cuts nice just keep it cool. it also has a good memory so if you heat it up there's a good chance it will deform when it cools down.i cut it everyday for about 10 yrs. ,once you get used to it you start to enjoy it, just remember no matter how thin the chips are it will always cut you!usually to the bone! ;D


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## joeby (Mar 6, 2009)

I'm not sure about the starting to enjoy it part. I ran 316 ball valve bodies and ball valve/fluid connection parts on CNC chuckers for a good while.

 Got used to it, never enjoyed it.

Kevin


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## machinist dave (Mar 6, 2009)

lol! when u gotta do it, you might as well enoy it. ;D


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## Noggin (Mar 24, 2009)

Same applies to 316 as well. Slow speed and give it some welly.


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## 10K Pete (Mar 24, 2009)

3.5" dia x 1/2" thick..... I'd be using a band cutoff saw to get those blanks out.

And no, not a little 5 x 3 either.

Pete


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## bearcar1 (Mar 24, 2009)

Yeah, a 30" DO-ALL would make short work of that cutoff operation.


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## Dhow Nunda wallah (Jul 1, 2009)

I've been machining stainless of several flavours for years, on a Jet 9 x 20.

Couple of tips, flood suds and HSS.

I grind all my own tools, it's easy, no top rake for stainless!
IE, leave the top of the tool square, leaves a nice finish.
Minimum cuts should be 0.005"
You can sneak up on it, but you MUST do it under flood suds.
As you said, it work hardens in a millisecond.

Leave the carbide to the big lathes/big shops.
Try your hand with some good HSS tool steel.

Rgds,
Lin


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## myrickman (Jul 19, 2009)

I have had good luck using Anchorlube as a SS cutting/machining fluid. Actually is is more like light green mayo......
BTW the stuff is non toxic and food use approved so let the chips fly. I got mine from MSC- still working on the gallon I bought 2 years ago.


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## SKIPRAT (Sep 2, 2009)

Hi Rick

just been reading your thread about you hating the machining properties 304 stainless.there is a material much worse than stainless 304 out there i am talking about Nimonic 90 the grand daddy of austenitic steels ! a few years ago i used to work for a company in the nearby city of Lincoln called Ruston & Hornsby they made large marine diesel engines and i used to rough out valves for the large engines.The job was done with a KDM copy lathe a monster driven by a 25hp motor if my memory serves me right this was done at around 350 RPM with a feed of 0.012'-0.016' per rev at 0.5' depth of cut.Now we come to the technology quite advanced for its day the tooling used was ceramic indexable tips with a liquid nitrogen spray for coolant .gotta keep it cool ! So my best way of machining it is revs down feed up 
and go for it but remember to keep it cool.
cheers Paul


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## rake60 (Sep 2, 2009)

There is always a worse one! 
For me it was Inconel 625. 

The manufacturer suggests:
*"Machineability:
Low cutting speeds, rigid tools and work piece, 
heavy equipment, ample coolant and positive feeds 
are general recommendations."*
What they don't tell you is to *BUY LOTS OF INSERTS!* 

Rick


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## macona (Sep 4, 2009)

One of our members at TechShop brought in a chunk of what I thought was stainless 4" x about 10". Chucked it up in the Monarch Series 60 (15HP) with a 12" 3 jaw.. Couldnt hardly touch the stuff. Carbide just bounced off. And I was even supporting it with a steady!

Think it must be inconel or monel. Something way tougher than stainless.

I did a pin for a winery this week out of 304. Turns real nice I think. Main problem is getting it to chip instead of long ribbons. Not in this life time and I was at darn near max feed on my lathe.


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## Krown Kustoms (Sep 4, 2009)

Rake, I was working on an iconel turbine for a small jet engine, that stuff is ruthless I butchered it until there was no repair, next time I am buying it already machined.


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