TURNING - arc is inverted?

[Anonymous]

So I am trying to turn an arc - and the toolpaths and preview look perfect when simulating in Fusion360.  When I post it - my PathPilot (LinuxCNC) controller inverts the arcs.  Very weird problem I can't figure out!

The Photo on the left is the Fusion preview and toolpath which looks correct - on the right is the preview screen on my Lathe that shows the Arc bowing opposite to the toolpath in Fusion!! Argh!!

Here's the G Code that was generated with the PathPilot Post processor posted by Adam on 8/25/15.

%
(1)
N10 G7
N11 G18
N12 G90
N13 G20

(PROFILE3)
N14 T1010
N15 G54
N16 M08
N17 G96 D2400 S750 M03
N18 G95
N19 G90 G0 X-0.45 Z0.2125
N20 G0 Z-0.0657
N21 X-0.4092
N22 G1 X-0.2492 F0.03937
N23 X-0.2279 Z-0.0721 F0.01
N24 G18 G2 X-0.228 Z-0.135 R0.0367
N25 G3 X-0.2461 Z-0.151 R0.0186
N26 G1 X-0.4061 F0.03937
N27 G0 X-0.4092
N28 Z-0.0622
N29 G1 X-0.2492 F0.03937
N30 X-0.2248 Z-0.0695 F0.01
N31 G2 X-0.2249 Z-0.1376 R0.0397
N32 G3 X-0.2401 Z-0.151 R0.0156
N33 G1 X-0.4001 F0.03937
N34 G0 X-0.45
N35 Z0.2125
N36 M05
N37 M09
N38 M01

N39 M30
%

[Anonymous]

Have you read the instruction file that comes with (at least the latest version of) the post?  Looks like it was updated at the end of Dec:: https://camforum.autodesk.com/index.php?topic=7481.150

I don't have this lathe (I do have a PCNC 1100 mill), but I've read a bit about the post for it.  This has to do with the post being modified to handle tools on the turret, the QCTP, and gang tooling.  From what I can see in the post code, if when you create the tool, you set the Turret number to something other than 0 on the "Post Processor" Tab it will be setup as toolType.XPLUS (meaning X coordinates are positive because the tool is behind the part).

this.toolType = tool.turret > 0 ? toolType.XPLUS : tool.manualToolChange ? toolType.XMINUS : toolType.GANG;

If the toolType is set to XPLUS then the G02 & G03 will be swapped:

            var inverted = g_tooling.getToolInfo( getCurrentSectionId( ) ).toolType === toolType.XPLUS;
            var G2or3 = inverted ? clockwise ? 2 : 3 : clockwise ? 3 : 2;

Are you using the turret?  Or is your tool on the front side?

Dave

[Anonymous]

Dave - thanks for the info.  I had not seen that updated post.

I will try tomorrow.   Hopefully that is a simple fix.  I did notice it outputs I J K moves vs a Radius arc however.

-B

[Anonymous]

Yeah, some of the turning posts are setup to have a user property for useRadius that will let you select either I J K or R parameters.  Looks like this one only does I J K.  I would have to be modified if you want to use radius instead.

Revisions noted in the file show that as removed in this latest version: "2015-19-11 : removed 'useRadius' 'using_QCTP' properties ( deprecated )."

Maybe it also wasn't being used in the one you have so the property may be there for you to set, but have no effect.

Dave

[Anonymous]

Dave - I have seen that useRadius parameter in some posts - it seems to be cleaner - i.e. less stuff going on in the post.

I cant wait til tomorrow morning to try it out - I was pulling my hair out wondering why my lathe was doing the exact opposite of what the simulation showed.

Thanks again!

B

[Anonymous]

So just some follow up. The new post worked well.  It did invert my facing op for some reason.  But at least my profiling arcs were perfect - here is some 304 turned on the grizzlyG0602