model symmetry

Discussion in 'Pro/Engineer & Creo Elements/Pro' started by g. bon, May 26, 2007.

  1. g. bon

    g. bon Guest

    I'm building a part with several pro/surface and Isdx functions.
    It's somethink like a bike, so it's have a symmetry plane.
    So, I'm modeling the half of the model and making symmetry function near to
    the end of the function tree (some details aren't symmetrics).

    Near the end the whole model is an open quilt so I've tryied 2 methods :

    1/
    - I make a planar surface in the middle plane
    - I merge this one with my surface (so I got a closed volume)
    - I solidify this volume
    - I make a symmetry function on this closed and solid volume

    2/
    - I make a symmetric quilt (with wymmetry function)
    - I merge the two quilts
    - I solidify this volume

    So, in both cases, one of the functions spend a lot of time (seems to
    depending on tangency condition in the symmetry plane).
    (In case 1 : symmetry - in case 2 : merge).
    a lot of time : I mean that this particular function spent more time for
    regen than all the other ones.

    So I'm wondering what would be the best approach in this sort of problem.
    I can't change precision because other functions.
    So what is the best method ?
    How handle this sort of symmetry/precision problem ?

    Thanks,
    GB
     
    g. bon, May 26, 2007
    #1
  2. g. bon

    David Janes Guest

    I'm building a part with several pro/surface and Isdx functions.
    It's somethink like a bike, so it's have a symmetry plane.
    So, I'm modeling the half of the model and making symmetry function near to
    the end of the function tree (some details aren't symmetrics).

    Near the end the whole model is an open quilt so I've tryied 2 methods :

    1/
    - I make a planar surface in the middle plane
    - I merge this one with my surface (so I got a closed volume)
    - I solidify this volume
    - I make a symmetry function on this closed and solid volume

    2/
    - I make a symmetric quilt (with wymmetry function)
    - I merge the two quilts
    - I solidify this volume

    So, in both cases, one of the functions spend a lot of time (seems to
    depending on tangency condition in the symmetry plane).
    (In case 1 : symmetry - in case 2 : merge).
    a lot of time : I mean that this particular function spent more time for
    regen than all the other ones.

    So I'm wondering what would be the best approach in this sort of problem.
    I can't change precision because other functions.
    So what is the best method ?
    How handle this sort of symmetry/precision problem ?

    Thanks,
    GB


    Any time I've spent a lot of time with merge or merge/cutout type operations, it's be the accuracy setting ('Edit>Setup>Accuracy'). Increase it by 10 or 100 fold (decimal left one or two places) and the problem was solved, no slowing, no hesitation, no agonizing over the results. The next time? seconds not minutes. Sometines it took enabling absolute accuracy (my favorite) and setting this to some accuracy of accuracies level (ratio of smallest part diagonal to assembly diagonal). This generally knocks some sense into Pro/e.

    David Janes

    David Janes
     
    David Janes, May 26, 2007
    #2
  3. Recheck your basics.

    Are your your midplane curves definitely planar curves? - sketches on the
    midplane, planar ISDX or curve thru points made planar.

    When you mirror the model [at the point it becomes assymetric] are you
    choosing the model name at the top of the model tree and mirroring the
    whole?



    Sean
     
    Sean Kerslake, May 29, 2007
    #3
  4. g. bon

    graminator Guest

    How about case 1 but mirror the part (or just the closed quilt) before
    you make it solid. Then solidify your first closed quilt, then
    solidify your second. Perhaps the second solidify won't need to
    calculate tangency to the solid geometry for it to solidify. Maybe.
     
    graminator, May 29, 2007
    #4
  5. g. bon

    David Janes Guest

    How about case 1 but mirror the part (or just the closed quilt) before
    you make it solid. Then solidify your first closed quilt, then
    solidify your second. Perhaps the second solidify won't need to
    calculate tangency to the solid geometry for it to solidify. Maybe.

    Has anyone ever tried the datum ribbon feature for ensuring tangency and good symmetrical merging? Another concern, echoing graminator's, is that surfaces be set normal to the mirroring plane (that's also where the datum ribbon helps). I guess I really haven't "gotten" what the problem is, beside slow regen speed, which was already answered. Are you looking for something that tricks Pro/e into not being so slow or that, when mirrored, doesn't EXAGERATE the accuracy problem? And it must as the part envelope just doubled with mirroring.

    David Janes

    David Janes
     
    David Janes, May 30, 2007
    #5
  6. Has anyone ever tried the datum ribbon feature for ensuring tangency and
    As I understand it the datum ribbon is for draft angles, setting normalcy
    should be robust for symmetry.

    My first question on midplane issues is always are the curves 'actually' on
    the midplane rather than 'theoretically' on the midplane. Classic example
    being someone has a curve thru points which all lie on the midplane and
    assume this generates a planar curve when it is actually/mathematically
    still a free curve until you change its Attributes to Quilt/Surf.

    Sean


    How about case 1 but mirror the part (or just the closed quilt) before
    you make it solid. Then solidify your first closed quilt, then
    solidify your second. Perhaps the second solidify won't need to
    calculate tangency to the solid geometry for it to solidify. Maybe.

    Another concern, echoing graminator's, is that surfaces be set normal to
    the mirroring plane (that's also where the datum ribbon helps). I guess I
    really haven't "gotten" what the problem is, beside slow regen speed, which
    was already answered. Are you looking for something that tricks Pro/e into
    not being so slow or that, when mirrored, doesn't EXAGERATE the accuracy
    problem? And it must as the part envelope just doubled with mirroring.

    David Janes

    David Janes
     
    Sean Kerslake, May 30, 2007
    #6
  7. g. bon

    graminator Guest


    I wouldn't have though you would want the curve to be 'actually'
    planar. Thru points is best, as I learnt from Dave. The 1st point of
    the curve has to be normal to the plane, assuming you're starting in
    the middle, i.e. on the mirror plane. Same for all the curves. Then
    the boundary surface would have normalcy constraint to the mirror
    plane on the adjacent boundary.

    It occurs to me I might be reading your post wrong. Perhaps by
    midplane curve you mean one that lies on the mirror datum. I was
    thinking of the ones going in the adjacent dir. Pity we can't put
    sketches up on this board.
     
    graminator, May 30, 2007
    #7
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