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Rotary table limit violation 4th axis


We have a small milling machine at the place I work, and I'm in the process of converting its native NCcad software to Mach3. The machine has a rotary table (4th axis) witch can rotate continuously (don't have end switch)  on the X axis.


I created a new post for the machine, just bare as it comes and added 4th axis and chose it as rotary table in the post builder. It seems the post works well, except when the toolpath crosses from 360 degree to 0 degree.So  my problem is when the crossing happens the machine doesn't cross over 360 to continue work, instead it turns all the way back to 0 and then. So it woudn't be a problem it in the process it would lift the cutter to safety. But it doesn't.


 As an example, I'm milling a correct dial for one small lathe we have at the workshop.


It posts the code:


N4860 X11.829 A357.22
N4870 X12.172 A357.62
N4880 X12.514 A358.02
N4890 X12.629 A358.61
N4900 X12.8 A359.7
N4910 A.5
N4920 X12.571 A1.69
N4930 X12.514 A1.98
N4940 X12.343 A2.18


One can see the tool traces on both side of the text all around the perimeter of work witch should't be there on Mach 3 toolpath simulation.



In the Mach 3 software I have some options for dealing with the problem but they don't really work for me, atleast. The Ang. Short only works for G0 but on the G0 the tool is most time on safe clearence and the Rot 360 rollover option doesn't make a difference. (even if id did it would be wrong to let the machine decide witch way to turn cause it might be the wrong way)


In the Post Builder I tried the option Retract / Re-engage under Axis limit violation, but the code was posted the same way, It didn't make any difference.
I kind of fixed the problem by changing the Axis limists to 10 turns (3600 degrees) in positive and 10 turns to negative. Now it posts it a bit better. but I think i just shifted the problem, once I need to work on something that requires more than 10 turns on rotary table I still have the same issue.


better code:


N7180 X11.829 A357.22
N7190 X12.172 A357.62
N7200 X12.514 A358.02
N7210 X12.629 A358.61
N7220 X12.8 A359.7
N7230 A360.5
N7240 X12.571 A361.69
N7250 X12.514 A361.98
N7260 X12.343 A362.18


Toolpath seems to be OK







As I understand what would be correct is the limits on the rotary table should be 0 to 360 degree but there should be User Defined handler on the Axis Limit violation.Something that tells the machine to lift to the clearance, then turn the rotary table to the 0 (or 360), then engage and continue with the toolpath. I kind of need some help on what should be there. TCL coding is not really my field Smiley Frustrated



Thanks in advance Koit



Re: Rotary table limit violation 4th axis

A couple options:

- if the rotary axis can handle larger values, just define the +/- limits as 9999.999 (or whatever)  You have 3600?

- Note the "Axis limit violation handling" block in the last dialog you posted a picture of.  Change it to "Retract/re-engage".  This will do a "lift up, rotate A, rapid down close to the part, feed down the rest of the way" set of moves (I think what you were asking for, and no tcl coding necessary on your end).

- If you want more control, you can create a UDE & code to handle resetting the A axis limits to other values (but it sounds like this is above your current level of knowledge)

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP5 + patch/TC11.2
I'd rather be e-steemed than e-diseaseled

Re: Rotary table limit violation 4th axis

Thanks for the reply, I tried the Retract/Re-engage on the settings where limits for the axis were 0 to 360 and the issue remained, when the toolpath was crossing over from limit it cut all the way around the workpice and continued on the toolpath when correct angle value was reached. But I will check it again, maybe it fixes some issues on.
Well I've wached on the UGS tutorial videos and I've done some examples posting the tool length, diameter and machining time type of things to the post. So I kind of have an idea what they are.
Secretly I kind of hoped it would be like adding something PB_CMD_fix_RAPID_SET, something that has allready solved by someone. Seems like a frequent issue, as I've searched an solution to my problem.
But thanks for the reply I increase the limits on the table also (I just chose 3600 as a nice round number)



Re: Rotary table limit violation 4th axis

I just had this issue. It seems that the underneath post code keys on the mom_warning_info being set by NX - and this is not being set reliably every time rotary crosses the limit - or if DPM max exceeded on the move - that warning is there. So: this feature is not very useful - just thought I would share this.

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