What grade of stainless is easiest to work?

[Carl Fisher]

I picked up some 304 but now I'm finding posts that state it's rather difficult to work with and that 303 may be a better option. Or is there something better?

What are your opinions? I'm planning to use it for nose cones and other exposed metals like trim rings and such. I'm working on a HF 7x10 with small carbide insert cutters.

 

[mredburn]

Your carbide cutters may be part of the problem. Looking at different inserts for my new holder I found that there are different cutters just for stainless. Whether its a slightly different profile or coating or both I couldnt tell you.

 

[Ed McDonnell]

For making parts that will be handled a lot, I didn't find 303 and 304 to be "stainless". That's something you might want to test for yourself before you buy a lot of it.

Stainless isn't that hard to turn unless it's been work hardened. Low-end mini-lathes struggle to take the kind of cuts that are needed for stainless. You have to cut deep enough to get under the material you work hardened on your last pass. You can do it, but surface quality probably won't be all that great. It was eye opening to see how much my little lathe could flex as it cut.

I've been pretty happy using 6061-T6511 extruded aluminum for the kind of parts you are talking about. The aluminum polishes to a mirror finish (if that's what you want) and is very slow to oxidize. A quick occasional wipe with a soft cloth keeps things shiny. And it is super easy to turn on my cheapo mini-lathe.

Just a thought.


Ed

 

[BocoteMark]

Hello Carl,

303 Probably is a better bet as far as ease of machining. I am an amateur but I have done a little machining with 303, 304, and 316 stainless. 303 Does seem to be less chewy and stringy than 304 and 316.

Have you tried using a high speed steel tool bit instead of carbide inserts? You may find a very sharp piece of HSS will cut with less force than carbide. When using HSS brush oil onto the cutter and don't allow the cutter to get too hot.

Mark

 

[Dalepenkala]

I picked up some 304 but now I'm finding posts that state it's rather difficult to work with and that 303 may be a better option. Or is there something better?

What are your opinions? I'm planning to use it for nose cones and other exposed metals like trim rings and such. I'm working on a HF 7x10 with small carbide insert cutters.

Carl I don't know what your setup is like but if your working with S.S. any grade from 300 series to 17-4ph or 15-5 you really should be using a stream of coolant. Mike and Ed bring up good points. Referring to Eds comment about workhardning the steel, that's why we always used coolant.

I don't know what carbide insert you are using but if your insert doesn't have a chip breaker you will get strings instead of 6's and 9's. If your getting the latter stings try kicking up you feed rate along with a tad bit more depth of cut.

Hope this helps!

 

[Rich L]

Many machinists call 304 a metallurgical mistake but its uses seem to far outweigh its difficulties. For 304 you need to pay attention to speeds and feeds and most importantly its propensity to work harden even with coolant. If you don't cut deep enough or if you dwell on the surface with a spinning tool or stationary tool on spinning work, you will likely have a bad day. 303 is called free-machining series 300 stainless and it can be turned and milled dry without to much of a problem unless you're hogging out big chunks. However, you'll get a better finish with some coolant.

Cheers,
Rich

 

[skiprat]

I use mostly 316 ( A4 ) and really only use coolant when milling or using slitting saws. I do have some insert cutters but as my drills, taps and dies are just HSS, and do just fine, then I often just use HSS cutters too.
I'm never really too worried about the turned finish as I use all the grades of good quality wet-n-dry to smooth things out anyway. All done wet.
Revs under 500 and a fairly heavy cut work for me.
The non-turned surfaces of my recent PITH hammer pen were done with a hacksaw, files and w&d. Using stainless can be hard work, but worth the effort.:wink: