Turning: High feedrate mode not outputting correctly during post processing

[Anonymous]

There are a group of us working on a post processor for turning on the Centroid CNC control.  One of the users has discovered that when we try to use high feedrate mode (instead of rapids) the CNC code doesn't switch between unit/rev and unit/min modes.  Please see the screen shots below.  It appears that the post is trying to output the 123 in/min move as if it were an in/rev feedrate.  I tried the generic Fanuc post on the post download page and I got the same result.  The post processor and a sample Fusion file are attached.  Is this a user error situation or a post problem.

Thanks!

[sportbikeryder]

The logic for a potential solution could be:

if high feed is selected

-Replace G0 call with a G98

-Insert High Feed feedrate

-revert back to  G99 for the next move 

As Franco noted, it appears this my be a universal issue across numerous posts. 

Thanks for the post creation Franco. I am just starting to use turning as I have only done milling prior to recently acquiring a small NC lathe, and literally stumbled upon this during my first posted program. I was attempting to be conservative and not use rapids...100 IPR was quite a Rapid attempt.

John

[Anonymous]

I think you may have found a "bug".  But, it is also possible that this was already accounted for and we are just doing something wrong.  Either way, there is a guy at Autodesk named Bob who is a genius with the post processors.  I'm hoping he will look at this thread.  

[bob.schultz]

Yes, this can be considered an issue with the post engine/post processors since an FPM feed is being provided to the onLinear function when the operation is in FPR mode, and there is no code to handle this situation.  You can add code to the post to mitigate this issue and output the high feeds in FPM mode.

Add the following code to the onLinear function.

  var x = xOutput.format(_x);
  var y = yOutput.format(_y);
  var z = zOutput.format(_z);

  var fmode;
  if (movement == MOVEMENT_HIGH_FEED) {
    fmode = getCode("FEED_MODE_UNIT_MIN");
  } else {
    fmode = getCode(currentSection.feedMode == FEED_PER_REVOLUTION ? "FEED_MODE_UNIT_REV" : "FEED_MODE_UNIT_MIN");
  }
  var f = getFeed(feed);
...
  writeBlock(gMotionModal.format(isSpeedFeedSynchronizationActive() ? 32 : 1), fmode, x, y, z, f);

You will need to change each occurrence of where the XYZ coordinates are output as shown in the last line.  The onCircular function should also be modified in case you go from a high feedrate move straight to a circular move.  Once again, all instances of the circular block output will have to be modified.

  var start = getCurrentPosition();
  var fmode = getCode(currentSection.feedMode == FEED_PER_REVOLUTION ? "FEED_MODE_UNIT_REV" : "FEED_MODE_UNIT_MIN");
...
    case PLANE_XY:
      //writeBlock(conditional(properties.type != "A", gAbsIncModal.format(90)), gPlaneModal.format(17), gMotionModal.format(clockwise ? 2 : 3), xOutput.format(x), yOutput.format(y), zOutput.format(z), iOutput.format(cx - start.x, 0), jOutput.format(cy - start.y, 0), getFeed(feed)); FRANCO 2/12/2018
	  writeBlock(conditional(properties.type != "A", gAbsIncModal.format(90)), fmode, gMotionModal.format(clockwise ? cw_franco : ccw_franco), xOutput.format(x), yOutput.format(y), zOutput.format(z), iOutput.format(cx - start.x, 0), jOutput.format(cy - start.y, 0), getFeed(feed));
      break;

[sportbikeryder]

Thanks for the reply and tips for post modification Bob. I have not yet implemented any of this, as I have just eliminated "high feed" from my programming at the moment. When I get a bunch of free time and have nothing else to do, I will tweak the post and see how she works 😉

John