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Rookie Question: editing constraints

Discussion in 'Using Alibre Design' started by Dephil, Jul 15, 2020.

  1. Dephil

    Dephil New Member

    I am a complete beginner at Alibre but it is really cool.

    Is there a way to directly edit constraints (as in select and delete a constraint) that has been placed?

    What is the fastest way to constrain 2 rectangles to be 'concentric' in 2D sketch? I mean a particular figure (rectangle) that is center-of-area constrained to another figure's center of area?

    Shouldn't mid-line constraint work for parallel lines?

    TIA -- Phil

    EDIT: I have done draw rectangle by center ... but it's not clear how to make the center explicitly constrained
    Last edited: Jul 15, 2020
  2. Hunter

    Hunter Senior Member

    Two methods I use:

    Construct rectangles using the centre option, and constrain their centres to each other.

    You can also draw a construction line corner to corner for each rectangle, and constrain the diagonal lines' midpoints to each other.
  3. Lew_Merrick

    Lew_Merrick Alibre Super User

    Hi Phil -- Under :System Options->Parts/Assemblies" is an option defined as "Sketches"
    You need to make sure tha your Sketching Constraints are visible. Then you can "select & delete" them easily. -- Lew
  4. idslk

    idslk Alibre Super User

    only to delete them as you self found out.
  5. NateLiqGrav

    NateLiqGrav Alibre Super User

    The thing you might be missing (and I think should be automatic) is that you can't pick two lines in a midpoint constraint. You need to add a sketch node and then midpoint that to the first line and then midpoint it to the second line.
  6. HaroldL

    HaroldL Alibre Super User

    Good catch Nate.
  7. Dephil

    Dephil New Member

    Thanks for the help.

    I am now trying to constrain two lines to intersect even though they are on different planes.

    I need to know what angle to miter the sides of this funnel so they mate correctly
    . pt_screen_grab_01.JPG
    (EDIT: base of 'pyramid' are not equal lengths)

    Along the left edge I have made two sketch lines perpendicular to the edge ... but nothing I do seems to get these lines to hit one another.

    Essentially I am trying to cut a section through the solid perpendicular to the edge so I can figure out the angles. (if there's an easier way I would sure like to know it, but getting lines on different planes to intersect seems like an important skill.

    How does Alibre work internally regarding whether points/lines are coplaner or simply close?

    Last edited: Jul 16, 2020
  8. Lew_Merrick

    Lew_Merrick Alibre Super User

    Hi Phil -- #1 Create a Reference Plane that "connects the space" where you need the Intersection to occur. Remember the Project to Sketch (called PTS quite regularly here) and use it as required. Also, Rename your constructed Reference Geometry, Sketches, and Constraints to create a "memory path" for later updates! -- Lew

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