# 316 still kicking my butt



## Aukai (Nov 11, 2020)

I did ok taper turning, and taper boring. Drilling was sketchy with just cutting fluid, next time I'll try mist coolant. When it came time to part with my 1/8" inserted carbide blade I had zero runout on the blade going in, and out square to the material, the tool was on height, the gibs not in use were locked down, everything for stiffness was done. 300,400,200 RPM, feed slow, med, and by hand, but it still rattled, I was trying strong mist coolant too. Now the bottom of my beverage container is not flat


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## Ulma Doctor (Nov 11, 2020)

Try 416 instead


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## Aukai (Nov 12, 2020)

Marine grade, or just harder to deal with?


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## mikey (Nov 12, 2020)

If corrosion resistance is important, stick with the 300 series stainless. Of these, 303 is the easiest to machine due to its higher sulfur content. 304 has less sulfur so it is harder to machine. It also work hardens more readily. 416 with its higher sulfur content machines pretty freely but it is not good when exposed to salt water so I would avoid it for stuff that you use on the boat.

I would go with 303 when you can for its improved machinability. Because it cuts more readily, it is less likely to work harden excessively (but it still can) so parting usually goes better. You still need to use sharp tools that you keep cutting continuously without dwelling and it helps to use a good cutting oil or Anchorlube but 303 will be much easier to work with.


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## mmcmdl (Nov 12, 2020)

I'll see if I can whip him up a nice slug of Monel .


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## Aukai (Nov 12, 2020)

BTDT with the Thomson bearing rod, from SOMEONE....
Thanks Mikey, I bought the slug of 316 for the challenge, I was doing OK till parting. What would be the calculation for parting 1.125 316, possibly a different blade?


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## Karl_T (Nov 12, 2020)

I see you are in Hawaii. So, good chance you need 304 if near salt water. By far, best material for salt water use.

I find cutting oil really helps with 316.  Once you work harden it, you are FUBAR. Keep your feed high and your speed slow. Tools super sharp.

I bought tons of 316 sheet at auction years ago. Seldom use it cause it is so hard to cut and machine.


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## Downunder Bob (Nov 12, 2020)

As with most hard to machine materials, a heavy rigid machine is your best friend. sharp tools come a close second.


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## projectnut (Nov 12, 2020)

Aukai said:


> I did ok taper turning, and taper boring. Drilling was sketchy with just cutting fluid, next time I'll try mist coolant. When it came time to part with my 1/8" inserted carbide blade I had zero runout on the blade going in, and out square to the material, the tool was on height, the gibs not in use were locked down, everything for stiffness was done. 300,400,200 RPM, feed slow, med, and by hand, but it still rattled, I was trying strong mist coolant too. Now the bottom of my beverage container is not flat



As mentioned there's a steep learning curve when dealing with stainless.  The company I worked for made 90+% of their own food processing and packaging machinery.  The most commonly used stainless was 316.  Before starting there I had never dealt with the stuff, and had no idea how to machine it.  Fortunately everyone there was familiar with it so they could give me the tutoring and tips necessary to be successful.  When using HSS tooling speeds were usually in the 40-50 SFM range.  When using carbide the speeds were usually around 300 to 400 SFM.  In those days we didn't use much carbide so the go to tooling was usually super sharp 1/2" or 5/8" HSS

I would also agree heavy rigid machines are your friend.  All are lathes were either LeBlond, Monarch, or American Pacemakers.  Our Mills were Tree brand.  I do cut a fair amount of 316 on my Sheldon.  The nice thing about this lathe is that it has an infinite variable speed drive and a tachometer (MachTach) that can read either RPM or SFM.  The toughest part is making sure you have a super sharp tool with the proper profile.

This information may help:



			http://www.qtstools.com/document_library/help-articles/Stainless%20Made%20Painless.pdf
		


Note the 2 bullet points under "Machinability on the second page:

1.  Chatter occurs if the cutting tool’s rigidity is inadequate.  

2.  Cut surfaces might be work hardened and more difficult to machine if cutting is interrupted or if the feed rate is too low.


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## Aukai (Nov 12, 2020)

Thank you everybody for the responses, I still have enough length for another shot. Thanks for the link above, I'll check it out


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## Jimsehr (Nov 12, 2020)

Aukai said:


> Thank you everybody for the responses, I still have enough length for another shot. Thanks for the link above, I'll check it out


Why don’t you just face the bottom flat ?
Jim Sehr


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## Aukai (Nov 12, 2020)

I will look at that, but I'm only able to chuck the lip, as the shot glass is all taper. I could V block it and mill it to maybe.....


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## projectnut (Nov 12, 2020)

Aukai said:


> I will look at that, but I'm only able to chuck the lip, as the *shot glass* is all taper. I could V block it and mill it to maybe.....



It might be an optical delusion but that looks like an awfully large shot glass.  With one that size you'll only get about 3 or 4 shots out of a 1.5 liter bottle of Brandy.


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## mikey (Nov 12, 2020)

Mike, I don't do production and don't own big lathes so the other guys probably will give better advice. However, because we live in Hawaii we do tend to use a fair amount of stainless steel here and I've turned a fair amount of 303, 304, 316, 416 and some grade of Aqualoy prop shaft that someone gave me. And I've mostly used my Sherline lathe to do it, although my little Emco 11" lathe does fine with them, too. Here is what little I know about it.

It is good to remember that stainless steel tends to retain the heat; the heat does NOT go out with the chip as much as with other materials. Consequently, SS will work harden quickly and the less machinable it is, the more it work hardens. This is why 303 is easier to work with than 304 or 316 and why 416 is so nice - the sulfur content. I don't know which grade of Aqualoy I have but surprisingly, it machines similarly to 303 and is the stuff I prefer for things like motorcycle bar ends and heavier, more solid stuff. I've turned and parted a lot of bar ends over the years on my little Sherline.

I usually prefer HSS tools for SS with a fair amount of side and back rake to keep temps down as much as I can. SS likes sharp tools so HSS/cobalt or T-15 is best (tends to retain its edge better under high temp conditions) but a CCGT-AK insert also works surprisingly well. The key is sharp. If you use an AK insert and it stops cutting, index the insert before you build too much heat.

I only use HSS parting tools with a 7 degree relief angle. I have tried several types of inserted carbide parting tools and they work but require a steady and continuous feed; since I don't like to use power feed when parting, I don't like to use carbide. HSS is much easier to use. You might be surprised at this but I prefer thinner blades and do most of my parting with a 0.040" P1N or a P1 blade. I can feel the cut better with them and rarely have to stop a cut due to work hardening.

When turning, I use a depth of cut that I know I or my lathe can keep up with. Once you start the cut, you have to keep it cutting without dwelling or you begin to pick up excessive heat. Use a good lubricant with extreme pressure additives if you can; that black pipe tapping stuff you can get at the hardware store works pretty good, as does Anchorlube. Even being careful, you will work harden sometimes; when this happens, drop the lathe one step slower and go deeper to cut below that layer. On my little Sherline, I bring the tool into contact with the work and literally turn the work by hand as I feed in with the cross slide until I break through that hardened surface, then turn the lathe on and go. Don't laugh; try it, it works.

When parting, I only feed by hand. If the work surface is hard I turn the work by hand and feed in with the parting tool until it begins to cut, then I turn the lathe on and feed in. Same thing if it hardens during the cut; stop and turn it by hand. Trying to part on a work hardened surface only dulls the tool and make the surface harder so if you get chatter when parting, stop the lathe and turn it by hand to break through. When parting, keep the tool cutting continuously; it is not a race so just keep it cutting and don't get in a hurry. Remember that your tool has to be sharp, aligned, etc. and use a lot of cutting oil. 

That's pretty much what I know about working with this stuff - pick the right material, use sharp tools and keep them cutting, lube it to reduce temps and increase lubricity and get under any hardened surface layers to keep the tool cutting. Hope this helps.


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## mmcmdl (Nov 12, 2020)

Aukai said:


> I still have enough length for another shot.




No pun intended Im sure !


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## Aukai (Nov 12, 2020)

Thank you Mike, good read, I'll look for a HSS blade, and better lubrication. I'm trying to get a comparison between a shot glass & the SS one, but it hasn't transferred over yet.


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## mmcmdl (Nov 12, 2020)

Mike ,to face that glass , make up a quick set of aluminum round soft jaws for your lathe . Bore a reverse taper 1/4" or so in the jaws and chuck it up on the taper .  Then just face it off or better yet , dish it .


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## Aukai (Nov 12, 2020)

I put tape on the lip, and got it to seat on the third tooth in on the 4 jaw, and faced it. The drill point inside has me concerned about base thickness for a dish.


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## Aukai (Nov 13, 2020)

I had to send the picture 4 times for it to get sent. The volume is smaller than a reg. single shot, I'll make the next one a little taller since it is a smaller diameter.


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## Aukai (Nov 18, 2020)

I took another shot at 316, I used a 1/16 HSS parting blade. The setup was the same, I hit the auto feed, and had my hand on the E stop button if things went bad. It went very well actually no drama at all, I might not have the right setup for the 1/8 carbide, but the HSS did very well.


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## mikey (Nov 18, 2020)

Nice finish, too!


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## Aukai (Nov 18, 2020)

Thank you, expert guidance from you, and everyone


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