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bmancini15-Moonstone
15-Moonstone
December 2, 2024
Question

Problem with Constraint Orientation Assumptions (Dec/02/2024)

  • December 2, 2024
  • 2 replies
  • 653 views

Hello everyone,


I'm still having trouble with "Allow Assumptions", see also https://community.ptc.com/t5/3D-Part-Assembly-Design/Problem-with-Constraint-Orientation-Assumptions/m-p/759215.


I still don't appreciate how they changed it and I also report equally anomalous behaviour.
I present to you with a simple example ASM file the fact that a completely assembled component with "allow assumption" assembled squared if repeated, can be incorrectly rotated.

In the attached asm file I have assembled a box and a square nut on a hole.
I created the files with Creo 2.0 to give the more curious that the problem does not occur in Creo 2.0.
If I try to reassemble this nut in the other holes with the "Repeat" command or by copying and pasting it with the "Paste Special" command, the nut in some holes is correctly squared while in others it is incorrectly rotated.

bmancini_1-1733151957347.png

For me it's a big nuisance because when duplicating the screws it forces me to add the third constraint to each element instead of relying on the good old "allow assumptions".

Does anyone have any solutions or advice to give?

Thank you
P.S. I'm using Creo 9.0.8.0

2 replies

Dale_Rosema
23-Emerald III
Dale_Rosema23-Emerald III
23-Emerald III
December 2, 2024

From my CMM days, there are six degrees of freedom and you have to make sure that all are constrained. I only use allow assumptions when placing a bolt, nut, washer or something where the actual position of the last constraint is not critical.

 

I was having issue where a part would flip because the last degree of freedom was not totally constrained so I would add an addition one for parallel or something like that.

 

https://community.ptc.com/t5/3D-Part-Assembly-Design/Cylinder-with-a-hole-two-insert-mates/m-p/57404

 

Catalina
CatalinaCommunity Manager
Community Moderator
December 9, 2024

Hi @bmancini,

I wanted to see if you got the help you needed.

If so, please mark the appropriate reply as the Accepted Solution or please feel free to detail in a reply what has helped you and mark it as the Accepted Solution. It will help other members who may have the same question.

Of course, if you have more to share on your issue, please pursue the conversation.

Thanks,

Catalina | PTC Community Moderator
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