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Replace sketch plane on an existing sketch.

Discussion in 'Using Alibre Design' started by Capn, Sep 24, 2019.

  1. bigseb

    bigseb Alibre Super User

    Could be, if you don't name things accordingly.

    If you ever do aerospace work you'll be blown away by the sheer amount of datums (points/axis/planes) required. Everything has to be properly defined and named.

    And for anyone that thinks this is overkill... each plane you create can be moved and/or rotated however you want. This might not always be necessary but when it is you'll be glad you did it. It only takes two clicks to create a plane.
  2. simonb65

    simonb65 Alibre Super User

    Having their own sketch planes would solve many issues with "targets" being deleted. I.e. create a sketch on a face ... the first thing would be that a plane would be created on that face (but while the face exists, the plane would be contrained to it). Now remove the face or feature that owns it and the plane could revert to be contrained to its location/position in the 3D space. Now the "target" has gone, but nothing breaks. The plane would then be free to be contrained to another face, hence moving the sketch and feature it is the foundation for! ...

    This would be sooooooooo flexable and you'd never break a model ... Win, Win, Win!
    anson likes this.
  3. NateLiqGrav

    NateLiqGrav Alibre Super User

    Being able to change the base planar object for a sketch is a good ability that we should have. But creating planes for every sketch is just a workaround for not having that ability right now. If we had that ability the planes between faces and sketches wouldn't be needed.
    However things would still break - every projected edge or dimension to edges of a face that no longer exist. Idk if the big boys have even fixed that one.
    anson likes this.
  4. bigseb

    bigseb Alibre Super User

    Using a face as a sketch plane is just plain lazy cad work. Every sketch should be on a plane.
  5. GIOV

    GIOV Senior Member

    Hello idslk,
    the correct word is "risk" and not risc also "script" and not skript. :)
  6. NateLiqGrav

    NateLiqGrav Alibre Super User

    I don't have a problem with using faces for sketching 99% of the time. In the rare case I do then I'm probably better off redesigning the part from scratch with the major changes in mind. Why waste time for that 1% case?

    There is textbook and then there is real life.
  7. bigseb

    bigseb Alibre Super User

    Not sure about the 'waste of time'. I click on the plane button, then select an existing face as reference geometry (cos I cheat) and then click ok. Takes seconds. Now I have a plane that can easily be moved/rotated.
  8. JST

    JST Alibre Super User

    When you create a plane that you want to have "permanent", is seems you must create it relative to the base planes separately from the model.

    If it in any way references the model in its creation, you run the risk of the model change now having the plane definition "lose its target". That can be deadly to the model.

    In Alibre, I have noticed that when there is NO error, you can re-constrain things and have them work. Once there is an error, it seems that Alibre may "freeze" that error, so that attempts to correct it by re-constraining do not get rid of the error. I almost always have to delete and re-do the feature, plane etc, once an error like that has appeared.

    This has been the case across 3 operating systems, and at least two different computers, so it is long-standing, and apparently not system-dependent.
  9. bigseb

    bigseb Alibre Super User

  10. JST

    JST Alibre Super User

    Care to comment further?

    When the source for the plane disappears, and the "lost target" message appears, I have found that Alibre often does not want to accept the new reference and "undo the error". Often the error continues even though everything seems correct. Same thing happens for other errors, but it is not always consistent. Deleting and redoing is in order, with attendant problems elsewhere.

    I just figured it was a quirk of Alibre that might get fixed someday. Meanwhile, I try to keep references limited to things which will not disappear in later modifications. The process is simple enough that it seems unlikely that I just fouled it up every time....but only when fixing the errors....not when establishing the planes to begin with.
    Last edited: May 18, 2020
  11. DavidJ

    DavidJ Alibre Super User Staff Member

    It does - but you can then re-define the plane. If you had sketched direct on face, you couldn't 'rescue' the sketch.
  12. bigseb

    bigseb Alibre Super User

  13. jc-s

    jc-s Member

    What about having an option to "create plane from sketch" so that if the sketch was placed on a face, rather than a plane, in one operation a new plane could be generated with the sketch on it and nothing breaks. Then most of the time you can sketch on faces but easily turn them into planes if you need to tweak them later.
    anson likes this.
  14. JST

    JST Alibre Super User

    That I know.

    I was referring to various errors that should be able to be "rescued", but for some reason, even when they are properly corrected, the error will not go away, and the part or assembly causes trouble due to the "open error". Re-referencing a plane is one of the ones that has caused this trouble.

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