316 still kicking my butt

Aukai

Aukai

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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:mad:
 
Marine grade, or just harder to deal with?
 
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.
 
:cautious: 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?
 
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.
 
As with most hard to machine materials, a heavy rigid machine is your best friend. sharp tools come a close second.
 
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:mad:
Click to expand...

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:


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