Turning stringy chip solution?

[Anonymous]

I went to my friends shop recently and they use Mastercam. He invited me to stop in because he was here in my shop to see me cleaning a birds nest of UHMW stringers off of the part and chuck jaws. Same thing happens with metal cutting for me and often a stringer will snag one from below and then stuff starts flying and now a metal birds nest. It would be ideal to use inserts just as they were designed and have those perfect little curls rain down but often I cant do that. My lathe is limited to 2500 RPM and since it is a TL-2 I can use only one tool at a time since there is no auto tool changing. So stringy things are a real problem for me.

 What Bob showed me was an interrupted axial cut parameter where you can limit the axial travel and eliminate all these stringer problems. It works I guess just like chip breaking does in HSM for drilling and it solved the problem for them.

  Here is a page    http://www.inhousesolutions.com/mastercam-2017-lathe/     and here is a quote from that page. 

"Dynamic Motion roughing extends insert life."

"Easily control chip breaks on stringy material."

  Bob's shop no longer has the turny stringy problem thingy. I am envious.

[Laurens-3DTechDraw]

This is something I indeed think would come in handy if you can't get the chip to break for whatever reason.

A question: Does it just stop, or actually move back a little? I think we would need to go back a little since just stopping would most probably create a long string. And would you want to give in this value?

But not sure how the competition handled this.

PS. I think Dynamic motion is the name MasterCAM uses for their Waveform/Adaptive turning strategy. Not this. But that doesn't mean this isn't a good Idea.

[Anonymous]

It sure worked for my friends shop.

[Anonymous]

Laurens I will get more details. I did not ask a whole lot about this because HSM does not have it and I don't use Mastercam.

[kb9ydn]

I don't use turning at all since I don't have a CNC lathe but I've often wondered why there isn't a roughing strategy for turning that just sort of picks away at the stock instead of producing a long constant width cut.  It would be sort of like the old trochoidal milling strategy (not like adaptive) where a series of decreasing diameter circles is used to cut into a corner.  As a control parameter you could use a maximum chip length; where the length of a cut is limited by the maximum length of a chip that you could get based on the part RPM, feed rate, and distance from rotation center of the part.  The actual tool path could either go in and out of the cut using little circles or it could follow the normal cut profile and just advance and retract to break the chip.

I'm sure there are other complexities to this I'm not thinking about but at least on the surface it seems like it could work.

C|

[Rob_Lockwood]

@Laurens-3DTechDraw wrote:

This is something I indeed think would come in handy if you can't get the chip to break for whatever reason.

A question: Does it just stop, or actually move back a little? I think we would need to go back a little since just stopping would most probably create a long string. And would you want to give in this value?

But not sure how the competition handled this.

PS. I think Dynamic motion is the name MasterCAM uses for their Waveform/Adaptive turning strategy. Not this. But that doesn't mean this isn't a good Idea.

---

Chip Break Off-

Chip break ON -

http://whatsnew.mastercam.com/2017/lathe_chip.html

Pretty sure that's what we're talking about here, right?

I'm actually not sure I follow the need to retract, so long as a dwell is longer than 1 revolution, the chip is broken, right? Maybe better than having the insert sit still rubbing.. I figured you could do this in post just by injecting a dwell code into the code at some distance interval, but retracting is much more difficult (read, probably requires actual toolpath development)

Also of note, Mastercam has nice looking turning roughing routines, the thinning along vertical walls is probably competitive with no-drag in legit-ness.

[Laurens-3DTechDraw]

I would disagree, I rather move back 0.1mm reenter the cut than stay in place. But not sure on the way Mastercam did it indeed.

Also if you would do a dwell. Would you assume the system to calculate one revolution in time? I mean that would be a little tricky with the CSS.(Of course easy calculation but not very easy to understand at the machine, keep in mind that a lot of people at the machine are not the programmers)

Actually, those paths look appalling.

If it's top down, or down up movement both cases I wouldn't want that.

So If they do he no-drag retraction it's ok, but not like your top image.

[Rob_Lockwood]

Yeah, I dunno how it would work out in the end. I'd theorize that pulling off of the material is pretty universally better, but I don't have much interest in doing any testing or anything; blasting high pressure coolant seems to do the trick to get chips to break.

I never run any profile type roughing routines like that anyway, as longitudinal roughing just generally seems superior. I'll confess once again though, i'm fairly novice to turning, at least achieving production type refinement. I generally only take a few passes at refinement and move along once I get an acceptable first article. Only production I've done is via Swiss, and the issues in that type of turning is quite different.

[Anonymous]

I don't know how to do this in Fusion or HSM (HSM noob...), but in the past I've had great success using the G74 cycle. Normally this is a chip-breaking drill cycle, but it works for straight cuts, too.

Not sure how it would work on a TL, but worth a shot.

[Anonymous]

Laurens,

  Mastercam does retract the cutter and you can assign just about any axial length and retract distance you wish is what I have been told. They use it for all but finish paths where evidently the retracts will leave minor marking. Bob swears by it and not at it which must be nice.

[Rob_Lockwood]

@al.whatmough

Someone should submit an idea into the Ideastation for this..

[al.whatmough]

[video]

[Laurens-3DTechDraw]

@al.whatmough

You insinuating now that this is already working?

[Rob_Lockwood]

@Laurens-3DTechDraw - nope, it came up on Instagram in the video post he's showing here. I'm sure he's just putting it up as a reference to it's purpose/function.

[al.whatmough]

@Laurens-3DTechDraw @Rob_Lockwood is correct.  I was just adding the video so that all the "ideas" for this Idea are in one place.

[Laurens-3DTechDraw]

@al.whatmough Nice.

While that full return in that video seems a little much if you ask me.

[Anonymous]

Laurens,
MC does not behave like the video which as you say is a bit much.

[Bunga777]

I usually use the G74 drill cycle to cut and process chips where machining is difficult.

First make a hole in the center with an insert drill, then offset it from the center, and divide the hole in several steps.

It is also possible to use the same cycle with a normal bore bit (although only straight holes can be machined).

I want to know how to do the same processing with HSMworks or Fusion 360.