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Attempting to use the NX Probing operations

[ Edited ]

I am posting this in the hope of saving other users the frustration I have been having over the past couple of weeks.  We have a probing license so I have been working on the Post, attempting to make use of the existing probing operations.  I thought I had it working OK.  Had tested it in Vericut, yes we have the license for that too, and on the machines using up a lot of expensive machine time in the process.  The code looked great.  However I was getting some strange results in a couple of my test files.  I discovered that there is a PR on this that is supposed to be fixed in NX 11. #7558968 The problem is when you are trying to probe an External Cylinder; the Z output is from the absolute not the MCS.  The fact that it is “Fixed in the next version” does nothing to help me at the moment and I am not about to go to my manager and once again tell him this. 

 

Matrix math is not my strong point so I need a fix for this.  If anyone has found a solution please let me know.

John Joyce, Manufacturing Engineer,
Senior Aerospace Connecticut
www.senioraeroct.com
Production: NX10.0.3.5, Vericut 8.0
Development: Tcl/Tk
Testing: NX11.0.1
21 REPLIES

Re: Attempting to use the NX Probing operations

Where (in the post) is the "block" for this?

Or is it a "macro"?

 

Just wondering what variable is being used for the Z word...

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: Attempting to use the NX Probing operations

Ken,

 

Thats the "strange" part of this the Z block is using mom_pos(2)

It is formatted as a coordinate. 

John Joyce, Manufacturing Engineer,
Senior Aerospace Connecticut
www.senioraeroct.com
Production: NX10.0.3.5, Vericut 8.0
Development: Tcl/Tk
Testing: NX11.0.1

Re: Attempting to use the NX Probing operations

In NX9 there appeared a new command called "MOM_convert_point". It allows you to set kin variables and give it a point vector and it will use that to do what NX would normally do (reverse kinematics.) I am not sure if there is any doc. GTAC will send you something (if not.)

NX10.03
Windows 7 Pro

Re: Attempting to use the NX Probing operations

On second thought - you mean model absolute not a main above a local mcs. Convert point will not help. If mom_msys_matrix represents the transformation from abs to mcs that is current - you will have to convert abs frame to mcs which means evaluate the point through the mom_msys_matrix.

 

Use:

 

MTX3_vec_multiply { u m w }

 

where

 

u is the point mom_mcs_goto(0),(1),(2)

m is the 3x3 matrix - get this from mom_msys_matrix elements (0) to (8)

w is the transformed point mom_pos(0),(1),(2)

 

I am surprised that GTAC doesn't feel the need to give you a workaround.

 

NX10.03
Windows 7 Pro

Re: Attempting to use the NX Probing operations

Thanks!!! I will give it a try.  should I set this to an array for the return value?

 

 

 

GTAC did give me a work around - program in absolute, and its fixed in NX 11.  Not much help in the real world.

 

Currently the PR is closed

 

"Siemens PLM believes that the problem you reported where probing an OD cylinder creates path in the wrong direction will be resolved by code changes made to the release of our product NX version 11.0."

 

Workaround:
~~~~~~~~~~
Move the part in space so that the MCS origin matches the absolute csys origin.  The coordinates output are then correct and the code can be used.  However, this is not always possible/easy when working with imported parts or assemblies created by designers.  This option for a workaround can't be used in all cases.

 

John Joyce, Manufacturing Engineer,
Senior Aerospace Connecticut
www.senioraeroct.com
Production: NX10.0.3.5, Vericut 8.0
Development: Tcl/Tk
Testing: NX11.0.1

Re: Attempting to use the NX Probing operations

This will work if you have an mcs that you want a point in the frame of and have a point in the frame of abs. If there are kinematic things happening to the points (table rotaries) then the mom_msys_matrix will not consider that (I think.)

NX10.03
Windows 7 Pro

Re: Attempting to use the NX Probing operations

Here is some code I just tested with at start of path. Seems to work (gives me the point in terms of the mcs that is currently active.)

 

set u(0) 0 ; set u(1) 0 ; set u(2) 1

set m(0) $::mom_msys_matrix(0) ; set m(3) $::mom_msys_matrix(3) ; set m(6) $::mom_msys_matrix(6)
set m(1) $::mom_msys_matrix(1) ; set m(4) $::mom_msys_matrix(4) ; set m(7) $::mom_msys_matrix(7)
set m(2) $::mom_msys_matrix(2) ; set m(5) $::mom_msys_matrix(5) ; set m(8) $::mom_msys_matrix(8)

set w(0) 0 ; set w(1) 0 ; set w(2) 0

MTX3_vec_multiply u m w

MOM_abort "\n\n$w(0),$w(1),$w(2)\n\n"

 

 

NX10.03
Windows 7 Pro

Re: Attempting to use the NX Probing operations

Please excuse my ignorance.

How can I use this to get the current position from the MCS based on where the absolute CSYS is located?
John Joyce, Manufacturing Engineer,
Senior Aerospace Connecticut
www.senioraeroct.com
Production: NX10.0.3.5, Vericut 8.0
Development: Tcl/Tk
Testing: NX11.0.1

Re: Attempting to use the NX Probing operations

Is this the problem?

"The problem is when you are trying to probe an External Cylinder; the Z output is from the absolute not the MCS."

If so - you could put the values nx is giving you (mom_pos represents abs coordinate) in the u vector and use the mom_msys_matrix to convert that to relative to the current mcs frame. So - you have a point that is in the abs frame - and you want it converted to the current mcs frame. I would do this in "PB_CMD_before_motion" routine for only this operation type.
NX10.03
Windows 7 Pro

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