Turning stainless steel

[welderskelter]

How hard is ss to turn. Any harder than steel. Never welded or turned any of it. Just wondering.

[JoeLee]

It's not any harder to turn than steel but it tends to stream and bird nest more than steel. Gets pretty hot too but all this depends on which series ss your talking about.
Some ss alloys are considered free machining, such as those that are sulfurized, but that stuff tend to irritate your throat.



JL..............

[Doozer]

SS can work harden if you let the toolbit or the drillbit dwell and rub.
Then it is super hard to get the cutting to begin again.
Get in fast, play hard, and leave quick is my advice.

-D

[Robg]

I got some stainless for a small project a while back but don’t know what series; it’s got a green paint identifier on it. I was pleased turning it with no problems and really liked the finish after turning. I think it was a bit harder on my tooling but not by much. I was a bit concerned how difficult it would be to turn but not not so much after doing it.

[chipmaker4130]

I turn 304L regularly with no issues. I use carbide inserts. The chips don't break, the swarf is nasty. It is stronger than you'd think and will cut to the bone if you aren't careful!

[MrWhoopee]

303 and 416 machine like buttah. 304 and 316 not so much. Turning with carbide is not too bad, drilling with HSS can be a real PITA.

[BCRider]

As you're seeing it all depends on which alloy you are trying to work with. Being a hobbyist that picks up their stock from scrap outlets or off random off cut shelves at bigger shops the SS I've worked has been a widely mixed bag. And the guys aren't downplaying how nasty the hard to machine stuff can be. If at all in doubt as to what you have I suggest going with lower than usual RPM for the lathe and mill and pay particular attention to what Doozer posted. Regardless of carbide or HSS you want to enter the cut with a full chip and never let up on the pressure. If you pause just long enough to shift your grip then picking up and getting the chip going again can require a lot of extra pressure due to how quickly the SS work hardens. Yep, it'll give you a nightmare it will. And if you're using HSS count yourself lucky that the chip start again. It cost me a few trips to the grinder to learn that lesson. And a few chipped brazed carbide tools too. Lower SFM speed, don't spare the coolant/cutting oil and keep that chip going with as smooth an advance as you can.

It's not like the chip needs to be a heavy one either. It just needs to be continuous up to the end. And then don't just stop. Back away instead with no a pretty sharp sudden action once you're at the shoulder. If the tool is in contact and there's no chip coming off then you have maybe two rotations of the part or cutter before you have a nasty work hardened face.

[Toolguy]

SS can work harden if you let the toolbit or the drillbit dwell and rub.
Then it is super hard to get the cutting to begin again.
Get in fast, play hard, and leave quick is my advice.

-D

Good advice for stainless. I use 303 as much as possible, it doesn't work harden like some other ones. It machines easier than 1018 low carbon steel. All the 300 series SS are fairly soft, though.

[lynnl]

17-4 is another that's nice to work with.

[oxford]

My only experience is with 304 stainless. I’ve only ever turned it with carbide, milled it with carbide or HSS endmills.

Ive never had a problem with work hardening while turning or milling. Drilling is another story and like the others said is gets pretty hard.

As far as welding, I would prefer to TIG stainless over mild steel.

[old mart]

There are many grades available, some workharden if your tooling dwells for an instant, some likes to attack you with murderous razor wire and some cuts beautifully.
Commonly, it is better to use carbide inserts intended for aluminium, they are sharp edged.

[polaraligned]

I try to stick to 303 when possible. I just made some custom bolts out of it and it machines nice. I learned all about work hardening drilling 304L when I was a youngster...it was an expensive lesson.

[epicfail48]

Depends on the grade of stainless. Something like 303 or 416 is a dream to machine, honestly easier than mild sometimes. 304? Absolute bitch, make the slightest mistake and itll work harden to what may actually be the hardest stuff on earth

[mickeyf]

Any simple way to tell what you got from the scrap bin, other than try a piece and see how it behaves?

[rickyb]

SS can work harden if you let the toolbit or the drillbit dwell and rub.
Then it is super hard to get the cutting to begin again.
Get in fast, play hard, and leave quick is my advice.

-D

Yep, just like titanium.