Collision checking with user rep

Roger Bombassei

Collision checking with user rep

I have found that collision checking doesn't work right with user representation cutters.

After learning to appreciate the collision checking feature I noticed that when replaying tool paths that have a user representation cutter I get a lot of false collision errors.

Dave Frank

RE: Collision checking with user rep
(in response to Roger Bombassei)

Hi Roger,

Thanks for the update. It may be that while user reps are allowed.... that Catia fits the shape into a 5 stage geometry, and then does colision checking from that.  If so, then we can make decisions based on that.

Perhaps Mark Chitjian knows, or can find out.

good observation.

Dave

Edited By:
Dave Frank[Forrest Machining] @ Sep 14, 2012 - 10:13 AM (America/Pacific)

Randy Hitzeman

RE: Collision checking with user rep
(in response to Roger Bombassei)

This is from the Help Docs:

 

 

See User Representations for details about the use of User Representations.

If an User Representation has an invalid profile, a warning message is displayed. The profile of the machining operation, not of the user representation, is taken into account.

When the tool is described by a CATProduct, it is defined by several sketch profiles.
You cannot mix cutting and non-cutting profiles.

Rules for collision checking are:

  • The lowest profile is always regarded as a cutting profile.
  • Next profiles are regarded as cutting profiles, until a SHANK, CLEANING, or HOLDER parameter is found.
  • Others profiles are regarded as non-cutting profiles.

If the user representation is modified inside a V5 session, modification will not be recognized and the collision checking will not be automatically re-computed. You must force the computation of the operation using the tool.

Example of scenario to avoid:

Inside the same session:

  • tool path is replayed with collision check active on an operation linked to a tool having a user representation => OK
  • the user representation is modified => OK
  • tool path is replayed again => KO: the collision checking is not automatically re-computed.

 

 

Randy Hitzeman

Roger Bombassei

RE: Collision checking with user rep
(in response to Roger Bombassei)

Thanks for the input guys.

I didn't see that info Randy posted in the R20 docs.  I'll have another look.

But I am using a CATPart user rep.  I'll give the CATProduct a try and see if that helps.

Randy Hitzeman

RE: Collision checking with user rep
(in response to Roger Bombassei)

Guys,

I'm attaching a properly built user representation that you can use as a seed model.

There are certain things that must be done in order to have a successful user rep.

1)  Build your sketch on the ZX plane, building your profile as if the Z axis is the tool axis.

2) The very FIRST element in your sketch must be a vertical AXIS line.

3) Build your profile from the tool tip, in a counter-clockwise direction, closing the profile at the end.

4) If you modify the tool, it may be best to completely redo the profile to maintain the order of elements in the counter-clockwise direction. In the past, I've had user reps that didn't work because of a radius or other element added later that was out of order. When the profile was completely rebuilt in a anti-clockwise direction, it worked.

5) All of your profile must be defined in the sketch, don't add chamfer or radius "features" to the solid after.      

Randy Hitzeman

Attachments

  • Manufacturing.zip (396.4k)

Bryan Carpio Felsher

RE: Collision checking with user rep
(in response to Randy Hitzeman)

Thanks Randy.

Roger Bombassei

RE: Collision checking with user rep
(in response to Roger Bombassei)

Interesting Randy.  I rarely use user reps and I finished the job using the CATPart user rep with colision checking turned off.

 

Next time I need one I will try your method.

Have you been using user reps with colision checking successfully?

The one I was trying was a 1" diameter with .75 corner rads.  It has a .20 diameter flat that the .75 rads come tangent to.

I drove the tangency lines on the floor using a .20 diameter cutter to make the motion.  I had to use a .41 contour offset to drive around the failsafe pin.

It cut the part perfectly in video replay.

I will see if I can attach my user rep.

Attachments

  • UserRep(1.000 x .750 x 1.000).CATPart (110k)

Roger Bombassei

RE: Collision checking with user rep
(in response to Roger Bombassei)

Woohoo!!! 

I tried the CATProduct method and all errors went away.

Thanks Randy

I am attaching my new user rep product

Attachments

  • userRep.zip (59.8k)

Randy Hitzeman

RE: Collision checking with user rep
(in response to Roger Bombassei)

Roger,

Considering how fussy V5 can be concerning user reps, I'm surprised that the CATProduct that you posted worked that well. I think you got away with one.

Please read my previous post on the Do's and Don'ts of building user reps.

There are some more rules that I should have listed. In earlier versions of V5, the name of the sketch determined whether is was a cutting or non-cutting section of the cutter. I believe that starting from V5R16, they changed how cutting and non-cutting sections are identified.

Old Method: Cutting and non-cutting sections were identified by naming the profile sketches either CUT or NOCUT.

New Method: The cutting and non-cutting sections are identified with a "String" type parameter. There are four types. Also note that these parameter names are CASE SENSITIVE.

1) CuttingType=CUTTER

2) CuttingType=SHANK 

3) CuttingType=HOLDER

4) CuttingType=BRUSH

Collision detection uses these parameters to determine cutting and non-cutting status of the individual CATParts inside of a CATProduct. If there is no parameter, CuttingType=CUTTER is assumed.

Roger, I strongly urge you to use my seed models. To edit it, go into the sketch and delete everything except for the very first AXIS line.

Build your profile in a counterclockwise direction.

 

Randy Hitzeman

Bryan Carpio Felsher

RE: Collision checking with user rep
(in response to Randy Hitzeman)


Really good advice guys.  I don't have much to add except that 90% of the time (I know...I know...not the best way from what I hear), I use a CATPart user rep.  If anything, just because it's easier to build and less files.

Since I never have used collision checking (I can't stand all the false collision warnings), I have never run into an issue as long as I create my user rep as Randy describes....ZX plane, create clockwise with profile sketcher, and name sketches CUT or NOCUT.

I have used the CATProduct user reps, but only when I needed to because the tool shape was complex or I needed to test a holder also.  99.999 percent of the time, I don't use a user rep at all.  I know a shop that ONLY uses user reps, and their tool catalogs are all built around user reps.  It looks cool, and I think it's a good idea if you're using TDM, etc...

Randy Hitzeman

RE: Collision checking with user rep
(in response to Randy Hitzeman)

Sorry,

In the previous post, I incorrectly listed the parameter for a brush type cutter as:

CutterType=BRUSH

It should be:

CutterType=CLEANING

 

In the MFG forum, there is a recent thread concerning probing.

I have a post about using the CLEANING type user representations for probes. 



In Reply to Randy Hitzeman:

Roger,

Considering how fussy V5 can be concerning user reps, I'm surprised that the CATProduct that you posted worked that well. I think you got away with one.

Please read my previous post on the Do's and Don'ts of building user reps.

There are some more rules that I should have listed. In earlier versions of V5, the name of the sketch determined whether is was a cutting or non-cutting section of the cutter. I believe that starting from V5R16, they changed how cutting and non-cutting sections are identified.

Old Method: Cutting and non-cutting sections were identified by naming the profile sketches either CUT or NOCUT.

New Method: The cutting and non-cutting sections are identified with a "String" type parameter. There are four types. Also note that these parameter names are CASE SENSITIVE.

1) CuttingType=CUTTER

2) CuttingType=SHANK 

3) CuttingType=HOLDER

4) CuttingType=BRUSH

Collision detection uses these parameters to determine cutting and non-cutting status of the individual CATParts inside of a CATProduct. If there is no parameter, CuttingType=CUTTER is assumed.

Roger, I strongly urge you to use my seed models. To edit it, go into the sketch and delete everything except for the very first AXIS line.

Build your profile in a counterclockwise direction.

 

Randy Hitzeman




Randy Hitzeman

Roger Bombassei

RE: Collision checking with user rep
(in response to Roger Bombassei)

Although the user rep product I posted didn't give errors, I found that it also didn't cut correctly in video replay.  :(

I did get a CATPart user rep to work with no errors and to cut the part correctly in video replay.

Some day I will get a CATProduct user rep to work.

It is good to find that collision checking does work when the user rep is defined correctly

Alex Smygov

RE: Collision checking with user rep
(in response to Roger Bombassei)

Hay Roger,

I don't know why your product user rep cut with no errors or worked at all, but it is not build correctly (NOT on ZX and Profile issues in the sketch). Randy has it spot on to perfection. I've used that method forever since Release 16 before it I was with CATParts user reps. I am surprized that I missed the CLEANING Feature all along... It is the best feature ever in my opinion.

Thanks again Randy.

Roger Bombassei

RE: Collision checking with user rep
(in response to Alex Smygov)

Randy's user rep product is the best solution I have seen so far

Thanks Randy