# Machining 304ss With 932m



## Bray D (Jan 10, 2016)

I got a request to machine some 304 the other day. I have a piece of bar stock on order so I can experiment before taking on the job. 

I've read a decent amount regarding the procedures/parameters for machining 304, but my biggest question now is the limitations of my machine. 

Does anyone have experience machining 304 on their 932? What were your experiences? What have you found to be the ideal cutter size/material/etc?


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## Chipper5783 (Jan 10, 2016)

What actual machining is required?  Whether it is a 932m, or most any other lathe, the piece of metal will not know the difference.  I have machined a bit of 316SS, and it has a tendency to work harden.  Regular HSS was not very happy.  I used quality cobalt HSS for drilling and tapping and carbide for turning - no big deal.

You may have to fiddle with it a bit.  I doubt you will have any trouble.


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## ch2co (Jan 10, 2016)

Take it with a grain of salt from a real newbie, keep it cool! I've found that S/S work hardens if you look at it crooked. But then I have a nasty look.

CHuck the grumpy old guy


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## qualitymachinetools (Jan 10, 2016)

It won't be much different than regular steel, other than as already said, you dont want to let the tool dwell or get too hot. Make sure you have some good end mills, (Name brand or US Preferred) and use the power feed if you can. 

 I used to work in a shop that made food machinery, and we pretty much only worked with stainless. 304 was not bad at all from what I remember. 316 was a different story, but still not that bad. Look up the feeds and speeds in the machinery's handbook and try to get close to that. 

 But there is nothing to be afraid of with it, it really was not bad at all.


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## TomS (Jan 10, 2016)

qualitymachinetools said:


> It won't be much different than regular steel, other than as already said, you dont want to let the tool dwell or get too hot. Make sure you have some good end mills, (Name brand or US Preferred) and use the power feed if you can.
> 
> I used to work in a shop that made food machinery, and we pretty much only worked with stainless. 304 was not bad at all from what I remember. 316 was a different story, but still not that bad. Look up the feeds and speeds in the machinery's handbook and try to get close to that.
> 
> But there is nothing to be afraid of with it, it really was not bad at all.



+1 on what Matt said.  It's not that bad.

Tom S.


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## Bray D (Jan 10, 2016)

Good to hear. I'm aware of the tendency to work harden, so I was hoping to maintain a pretty aggressive feed. I'll reference the Machinery's Handbook for proper feeds/speeds for sure. I've worked with low carbon steel a good bit, and haven't had much issue. That being said, everything is pretty happy with a 1/2" or smaller end mill. 

I don't have a print, but he mentioned grooving/slotting. No drilling or tapping that I'm aware of. I'll play around with some of the end mills I have on hand once my sample arrives. After I'm confident I can machine it with success, I'll request a drawing and I'll buy a high quality end mill specifically for this job. Sounds like solid carbide is the way to go. 

I have a Noga mini-cool, so I'll up the flow rate on that to try and keep the tool happy.


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## Rich V (Jan 11, 2016)

If you will be slotting in 304 consider getting a roughing end mill to do the bulk of the cut. Roughing end mills can cut a lot more metal with less horsepower and chatter than regular end mills. Their main drawback is they leave a rough surface on the sides that will require a finish cut with a normal end mill. Use an undersized roughing end mill then finish with carbide, you'll like how it works.
http://www.use-enco.com/1/3/roughing-end-mill


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## Bray D (Jan 11, 2016)

I have the Interstate set of cobalt roughers and they're awesome for removing a lot of material. I'll give them a shot for sure.

I have the material on order, but haven't received a shipping notification yet. I'm hoping it shows up tomorrow.


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## Bray D (Jan 12, 2016)

Test cuts were a success. I tossed my 1/2" rougher in the collet and took a few passes. I started by cleaning up the top face, then milled a full length 1/4" groove. Took up to .050" DOC without issue. 

I'm waiting on a drawing for the project that's coming up, but I foresee it requiring smaller end mills which should be even easier yet. I'll wait until I have dims, then I'll order some fresh American made carbide cutters for the project. I should be good to go.


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## qualitymachinetools (Jan 13, 2016)

Looks good! I personally don't recommend carbide end mills on a manual mill but that may just be me. I usually chip or break them long before they would wear out, and they cost too much for that. For cnc, absolutely. But for Manual I have better luck with a good hss end mill. Just my opinion though.


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## Bray D (Jan 13, 2016)

That's a legitimate concern indeed. I plan to talk with the tool crib guy here at my 9-5 to see what we have in stock and what he might suggest. I'm leaning towards carbide right now because I haven't been bit by it yet (no chipped bits so far), but I could probably be talked into a high performance HSS cutter as well.


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## rmack898 (Jan 14, 2016)

I work with a fair amount of stainless 304, 309, and 316. Quality HSS tools on manual machines without issue. Aggressive feed is key so as not to work harden, I also tend to run my spindle speeds a little slower than what you might see in the charts.


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## Bray D (Jan 15, 2016)

My test cuts were with a cobalt rougher and it did well. 

I'm still waiting on dims before I order tools. Hogging out a slot is one thing; we'll see how I do once I'm required to hold sizes and such.


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