Turning stainless steel

[Willy]

About 8 years ago I had a request from a friend to make a half dozen boat prop shafts each about 6 ft. long out of 316 and although a little hesitant after a bad experience with some work hardening manganese steel I took the job on.

It cut very nicely, left a beautiful finish and was a treat to work with because I did not let the tool rub, only cut while in contact with the work. The previous bad experience with the manganese steel had left a bad taste in my mouth and got me out of that nasty habit of dwelling in the cut.

The taper on the shaft was cut with carbide tooling but the keyway, drilling, and single point threading were all done with HSS tools.
I'm not scared of it anymore.

[Bented]

Depending entirely on the work holding I turn 303 using the same feeds and speeds as mild steel, 400-700 FPM , .050-.100" DOC and .015-.020" FPR for roughing, this is conservative.
Increase the spindle speed and decrease the DOC and feed rates for finishing.

304 a bit slower, if the values are to conservative a mass of stringy chip will be created.

[JRouche]

Depending entirely on the work holding I turn 303 using the same feeds and speeds as mild steel, 400-700 FPM , .050-.100" DOC and .015-.020" FPR for roughing, this is conservative.
Increase the spindle speed and decrease the DOC and feed rates for finishing.

304 a bit slower, if the values are to conservative a mass of stringy chip will be created.

what he said. If you can get 303 grab it. 304 has a crappy surface finish so expect that. It does not deter the usefulness of 304. I think it has a better mech strength. JR

[polaraligned]

lol, then take Doozers advice and just don't dwell

No. Last time I dwelled I ended up with my 4th kid....

[BobL]

About the middle of 2021 I finally managed to complete my wife's 2020 Xmas present - this is pretty good for me as I'm known to take many years to complete family requests.
Up until then I had done very little SS turning so I took on the job with some trepidation, but I only had to make one part twice and that was because of a measurement stuff up.

All the metal is SS except for a couple of custom phosphorus bronze washers.
I used 316 for the bearing holders, shafts and collars, and 304 for the brackets, all from a steel merchants offcuts shelf.
I used carbide inserts for all the boring and some of the exterior turning otherwise I use Crobalt bits.
Worked way better than I expected.


I also milled the timber from a sizeable log back in 2008?
Oh yeah if you want to know what it is, its a wool carding machine, turns tangled hanks of shorn wool into hanks with the fibres all running in the same direction .

[JRouche]

About the middle of 2021 I finally managed to complete my wife's 2020 Xmas present - this is pretty good for me as I'm known to take many years to complete family requests.



I used carbide inserts for all the boring and some of the exterior turning otherwise I use Crobalt bits.
Worked way better than I expected..

Funny, she did get her present right? Im sure,,

Ummm, I dont finish things for some reason. But what caught my eye was the use of Crobalt? Most folks dont use that or dont know about it. I do. I just have never seen anyone else talk about it. I have a bunch and it is great with metals that might get hard during turning, SS. No big deal. I like the tool blanks.

Neat to see some one else uses the stuff for difficult SS.

Crobalt is a member of alloy like Stellite that some folks seem to cherish but much less expensive. Same results. JR

[Dave C]

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.

I used to work at a place that used 316 and it came with green painted ends.

[boslab]

Old but relevant
https://sassda.co.za/wp-content/uplo...-Chart-A32.pdf
mark

[Richard P Wilson]

OK O know I'm going to regret asking this, but WTF is Crobalt? Cobalt, yes I know all about that but Crobalt?

[reggie_obe]

OK O know I'm going to regret asking this, but WTF is Crobalt? Cobalt, yes I know all about that but Crobalt?

Trade name for a specific Cobalt alloy.
http://crobalt.com/whatiscrobalt.htm

[lynnl]

I also milled the timber from a sizeable log back in 2008?
Oh yeah if you want to know what it is, its a wool carding machine, turns tangled hanks of shorn wool into hanks with the fibres all running in the same direction .

BobL, that's about the most highly figured wood I've ever seen. Is it really that pronounced, or is the camera image accentuating the figure?

What is it? I assume something specific to Australia.
(the wood, that is...)

[BobL]

BobL, that's about the most highly figured wood I've ever seen. Is it really that pronounced, or is the camera image accentuating the figure?
What is it? I assume something specific to Australia.
(the wood, that is...)

Its the real thing. Its common name is "Marri" or "Western Australian Redgum". It looks like a eucalyptus and was up until a few years ago known as "Eucalyptus calophylla" but is now know as Corymbia calophylla which is technically a Bloodwood. It sometimes contains fist size pockets and long streaky veins of liquid blood red resin. These resin streaks were more pronounced in mature trees and caused large pieces of the wood to fall apart so it was despised by saw mills and left behind in forests and burned on farms and ranches. In the last 20 years it has become prized for furniture and even floor boards. The bench seats at a local church are made of it and they look stunning, although most of the congregation wouldn't know what it was or care if they sat on plastic benches.

Here is a picture of the log I used to make the carding machine from when I first milled it in 2008.
As the wood ages the figure becomes more pronounced. The brown streaks are dried resin.

Here's a few more pics of the wood used in the Carding machine.
The large spike covered cylinder was made like a thick walled barrel as I was going to put lead short in the middle to give it dded angular momentum but it turned out to be heavy enough without.

And the underneath.


And here's why it's called a bloodwood.
Nope that is not a chainsaw injury but the resin from pockets in that tree above.
I took this photo to send it to my BIL as I was sick of him sending me photos of his surgical procedures showing stitches and staples up his back like a zipper.

[BobL]

Funny, she did get her present right? Im sure,,

Oh yeah she got the present.
Here is what she does with it.
Turns this;

Into this.

She then either spins the wool or dyes it and uses it to makes woollen sculptures like this

The sheep , coyote and the bust are all made of wool.

[BobL]

I use the crobalt bits in inverted diamond point tool holders like this
The holders come with that beaut grinding jig.
Apart from inserts I hardly uses anything else for general turning.

[lynnl]

I have heard of "marri," but knew nothing about its characteristics.

Around here we use the term "red gum" to refer to the heart wood of what we know as the "sweet gum" tree (liquid amber or liquidambar.) Much despised by home owners, because of the billions of spiky balls it produces to fall on lawns to be stepped on, or raked. It too exudes a lot of sap, but nothing as visually interesting as that marri. Nor is the wood so highly figured; in fact it has almost no figure. Serves mostly as a secondary wood in furniture making.