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5 Axis Table Table post

Hi All,

 

I am in the process of starting my first 5axis post in post builder where I can use either the generic or the Fanuc 30i as my base post, is there anything I should look out for with either of these? I have mostly created 3axis posts and am looking for any common issue before I go to far.

 

Any help greatly received,

 

Best Regards

 

Dave

Regards

Dave
NX10.0.3MP13
NX11.0.1
Production
TC10
Vericut 7.3,7.4.1,8.0.2
17 REPLIES

Re: 5 Axis Table Table post

[ Edited ]

Have a look at the sample postprocessors that come with the install in the machine tool library.
They are already equipped with some nice 5-axis functionality to support G43.4 (RTCP) and G68.2/G53.1 (work plane).
Take some time in understanding how its built and you only need to add your specific features to it.I don't know in which version you are working, but try to start with the ones that come with NX9. 

When you are working with NX8, you might have an issue with those, and i advuise you to use the NX8 ones. This is because there is new functionality added in NX8.5 and in their posts to retrieve the MSYS data.  

 

Regards,

Gerrit Koelewijn

Re: 5 Axis Table Table post

Thank you Gerrit,

I will take a look at those files, we are currently on NX7.5 but evalutating NX9.0.2 at the moment.

Best Regards,

Dave
Regards

Dave
NX10.0.3MP13
NX11.0.1
Production
TC10
Vericut 7.3,7.4.1,8.0.2

Re: 5 Axis Table Table post

Gerrit

 

Which table/table post supports RTCP? We recently purchaced a OKK trunnion with RTCP and I've learned it's about more than just ouputting a G43.4. We're currently using Postworks and the code seems identical to head/head output. I'd rather use an NX post but when I asked someone at GTAC what it would take they said they'd never heard of RTCP for a trunnion. Any help would be greatly appreciated in that Postworks requires a lot of APT formatting.

 

Ray

Re: 5 Axis Table Table post

We use RTCP and what it does is lets you output all your X,Y,Z code from your machine coordinate system.  It's basically posting out everything from your MCS coordinate system regardless of the tool's orientation. It is nice in some ways and annoying in others.  The main thing I don't like is the tool axis is not always parrallel to Z so when you setup the post to position in X&Y then approach in Z it is sometimes producing some sketchy moves.  Also make sure to note that when you turn on G43.4 (for a Fanuc 31i) the line in which you instate RTPC is not turning it on all the way, it's only turning on the height offset portion of the compensation.  We got into issues with this as the machine will "catch up" to where you told it to go after it reads in the 5 axis portion of the comp.

Jake Hardwick
CNC Programmer
Senior Aerospace AMT
Production NX8.5.3.3 Beta testing NX10.0.1.4

Re: 5 Axis Table Table post

Hello Ray,

 

I dont have all the OOTB postprocessors in my head, but for instance the ones coming with sim08 (table table) are a very good starting point.

The functionality per controller might be a bit different, but for Fanuc they support:

  • WCS Rotation (G68) or Swiveling (G68.2 and G53.1)
  • For Multi-Axis, Axis (G43.4) or Vector (G43.5)
  • For Multi-Axis, Fix Machine or Fix Table coordinate output

It will require a basic knowledge of TCL and the NX MOM environment, to modify the postprocessors to your needs.

 

 

Regards,

Gerrit Koelewijn

Re: 5 Axis Table Table post

Thanks Jake, that sounds like what I'm seeing. I'm old school with trunnions (putting MCS at center of A and C) so it took me a bit to wrap my head around this. I've searched through Postbuilder and haven't found the switch (I'm hoping it's that simple) to turn it on. Just for the hell of it I used a gantry style post and the code is "essentially" identical to what I'm seeing from Postworks.

 

Ray

Re: 5 Axis Table Table post

Jake,

 

This is a known issue, and it has quite a simple solution to it, that requires a bit of work in the post processor.

The easiest way to do this, is doing the positoning in Swiveling or WCS rotation mode (Fanuc, G68 or G68.2). Rotate table (if still needed), and after that you position in XY based on the rotated workplane, you can cancel the workplane rotation and then activate RTCP, the next motion is a X,Y and Z motion to the RTCP (MCS) coordinate.

Above is best for Table Table.

Other comfigurations, might need a different approach, but the trick is to let the controller do the math, because the conroller only knows where the piece is at the table.

 

I hope this helps.

 

Regards,

Gerrit Koelewijn

Re: 5 Axis Table Table post

[ Edited ]

Sorry for hijacking your thread Ray!

 

We have a head table (B over A which isn't a configuration that's in any of the samples or documentation, which is understandable since you don't see too many machines setup this way) and what I ended up doing was taking the Z position and the table rotation; and also taking the X position, head angle, piviot distance, and the gauge length of the tool in the MCS coordinate system and using all of that to trig out a "fake" RTPC position.

 

I posted out the position where the tool would be after G43.4 was turned on then made the machine go there, turned on RTCP, and then output the "same" position in MCS coordinates.  I did basically the opposite of what you suggest by doing all the calculations myself lol Smiley Happy

 

 

(SEQ-RUF-SURF-1)
X-160.3353 Y-.243 A.235 B1.79
G43.4 H110
X-160.7482 Y-.1782 Z15.7988  <-- this is really just a straight Z-axis approach move.

 

Jake Hardwick
CNC Programmer
Senior Aerospace AMT
Production NX8.5.3.3 Beta testing NX10.0.1.4

Re: 5 Axis Table Table post

[ Edited ]

Hello Jake,

 

For a Head Table Machine tool this is a good approach :

  1. Move Table to Correct Orientation Angle
  2. Set Head Straight up
  3. Move to Max Z (Machine Limit)
  4. Activate TCP
  5. Move XY in TCP coordinates
  6. Tilt head in correct orientation (machine should move around tool tip)
  7. Deactivate TCP
  8. Activate Tilted Workplane
  9. Move XYZ to Workplane Position (This should result in a Z (along Machine Axis) Motion only)

In case of a multi axis operation, the preceding steps 7 to 9 are are to be omitted and following line to be added:

7.  Move (XY)Z to the same initial TCP position as above.

 

But depending on your preference that could be a different one.

Regards,

Gerrit Koelewijn

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