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Tooling to Machine this stainless roller?

mmurray70

Stainless
Joined
Jan 11, 2003
Hey Guys I have to make a roller out of 6" dia 316 ss, see picture below. Wondering what to do for tooling for the middle section?

Was thinking about using some kind of round profiling insert but not really sure what to buy, and im worried about stringy chips. If I use a larger round insert say 1/4 - 3/8 diameter am i going to run into issues with chips? I could reach everything with a neutral VNMG or VCMT tool. Any suggestions?
 

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DNMG433 OD turning tool with the insert at 93° would profile that no problem. That tool can do a -30° taper into the material.
So I would need a left and a right tool? Would be nice to do it all with one tool if i could.

The flange at the end is 19 degrees, I drew it so I could just fit in a VNMG. Originally the customer wanted it 90 degree but he said this would be ok.
 
I would just use TNMG's on that.

The whole thing could be roughed out with a 0* holder, and then come back with a LH and a RH holders to finish.

Or you could just alter back and forth with just the LH and RH holders if you don't have a 0* holder.


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I am Ox and I approve this post!
 
I could reach everything with a neutral VNMG or VCMT tool. Any suggestions?
If it's just 1pc and you're not too concerned about cycle time, then a neutral VNMG will do it.
If you have a LH and RH DNMG, roughing with those will be a lot faster, then finish with the neutral VNMG.
 
Id like to try cutting it like this, but worried about the chips in stainless. Can this work with a round insert say 3/8 diameter RCMT in 316? Or will it be a stringy disaster?

 
So I would need a left and a right tool? Would be nice to do it all with one tool if i could.

The flange at the end is 19 degrees, I drew it so I could just fit in a VNMG. Originally the customer wanted it 90 degree but he said this would be ok.
You could machine the whole profile with one RH or LH DMNG 433 tool. No need for a neutral tool. DNMG is WAY stronger insert shape than a VNMG.
 
Phil - did you open his link up, or just see what is shown on the mini pic?
Your 55* isn't going to doo more than rough.

A 0* (neutral?) 35* diamond may phyically be able to doo it complete, but it will take several edges and waste a whole lot of time babying a pencil tip insert. Even more likely would be to blow a tip and then take out the holder on such a big part.


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Think Snow Eh!
Ox
 
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You could machine the whole profile with one RH or LH DMNG 433 tool. No need for a neutral tool. DNMG is WAY stronger insert shape than a VNMG.
Am I missing something? Leaving a lot of material on with DNMG.
 

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Phil - did you open his link up, or just see what is shown on the mini pic?
Your 55* isn't going to doo more than rough.

A 0* (neutral?) 35* diamond may phyically be able to doo it complete, but it will take several edges and waste a whole lot of time babying a pencil tip insert. Even more likely would be to blow a tip and then take out the holder on such a big part.


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Think Snow Eh!
Ox
My bad. I just looked at his pic and did not click it. Need a RH and LH tool.
 
Can this work with a round insert say 3/8 diameter RCMT in 316? Or will it be a stringy disaster?
Yes it can work. Your chip formation will depend on your cut depth,feed rate and sfpm. Nothing out of the ordinary. But it probably requires a more stable setup, round inserts love to vibrate in my experience on a lathe.
 
How come y'all are so opposed to rounds ? Looks like a couple of sharpish corners on the drawing that won't work but otherwise ... I've used rounds a fair amount and kind of like them. They have a little different needs because the in-cut surface is so large but heck, we're supposed to be machinists, no ?

On the other hand, I hate dnmg's and even worse, vnmg's. Those things are fragile, don't plunge well, and you have to run rights and lefts to get to both sides. Poop on that.
 
So I found an old 3/8" round insert tool on the manual lathe from Kennametal. No screw, these inserts tap into a tapered hole, called K-lock or something. Its still current so I ordered a box of inserts for it, going to give it a try. Seems to be a good fit for my part.

Anybody have any suggestions on depth of cut and feed for this? https://www.kennametal.com/us/en/products/p.rcmk-mp.3787508.html
 

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How come y'all are so opposed to rounds ? Looks like a couple of sharpish corners on the drawing that won't work but otherwise ... I've used rounds a fair amount and kind of like them. They have a little different needs because the in-cut surface is so large but heck, we're supposed to be machinists, no ?

On the other hand, I hate dnmg's and even worse, vnmg's. Those things are fragile, don't plunge well, and you have to run rights and lefts to get to both sides. Poop on that.
Glad someone here likes round inserts. Any suggestion on depth of cut and feed for a 3/8 round tool?
 
I think you'll have much better time with the DNMG rough & VNMG finish- they are not "fragile" if you follow the mfg's recommended DOCs, feeds & speeds. If you have to meet tight tolerances or are not grinding to finish then you will want the pointy tools. We've run 43" length rollers with more features then yours and couldn't get the massive contact area of the rounds to work accurately enough with a good finish but maybe you'll do better. 316 is expensive, the pointies will guarantee that you don't junk material. D&VNMG's in stick tools can be had for under $100 each.
 
I'm not exactly sure what is the real fuss with this part ...

Pass1: DNMG for whatever it can do to the 30 deg. limit.
Pass2: VNMG for what's left on the front
Finish pass: You can probably use a .125 full rad top notch ( might need to grind a 45 at the back of the toolholder but hey )

In my wheelhouse, I have 2, 3 and 4 mm full rad Iscar groovers just for the purpose.

Your only limit to which tool to use is the fillet radius in the corners.
 
I think you'll have much better time with the DNMG rough & VNMG finish- they are not "fragile" if you follow the mfg's recommended DOCs, feeds & speeds.
Yeah, if you take pansy cuts, like on a haas.

I'm used to lathes with balls .... if I wanted a toy I'd buy one :)

Rounds do need to be loaded, if you let them skate they will chatter. But that's just the same as anything, just a little more extreme.
 








 
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