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Thread: Sweep or Extrude without Twist

  1. #1
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    Unhappy Sweep or Extrude without Twist

    Greetings,
    Please is there a way to sweep or extrude a shape (rectangle) along a 3D polyline, which is made up of a number of segments each starting and end at a different elevation, without having the shape at the end of the line twisted. that is, there is a twist along the path and this can be seen in the plan view (Top).
    I have tried every which way, but always end up a twist relative to X-Y plane

  2. #2
    Join Date
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    Can you show us the file or a screenshot of it ?

    I use the SWEEP command a lot for drawing piping and never did i see anything twisted, although i use 2008, in wich i cant seem to sweep a 3D polyline.

  3. #3
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    SWEEP might work if you were to use the GUIDES option but without a DWG file it's difficult to say.
    I'm Reese. Sergeant Tech-Com, DN38416. Assigned to protect you. You've been targeted for termination.

  4. #4
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    Greetings Veggetossj,
    i assume you are using a circular profile. Try this:
    Start a 3D polyline and @100<0<-10, @100<315<-10; change the view to an isometric so the beginning and end of the line just drawn. Change the drawing plane to be perpendicular to the first part of the line (rotate the y-axis 90°) and draw a rectangle at the start of the line - point, @5,5. Then select EXTRUDE, with the rectangle and 3D polyline as the path.
    Change viiew to TOP and zoom in to the end of the line - note that the vertices are not above one another, ie there is a twist.
    Thanks.

  5. #5
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    Greetings Kyle,
    Please see reply to Veggetosj.
    Where is the GUIDES option in SWEEP? Thanks.

  6. #6
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    ok so i tried it myself and indeed the second section seem to be twisted when using SWEEP, i think this is due to the line's direction.

    I assume u wish to have it like as it were horizontally

    Honestly i have no idea how this happens or how to change this.

    I will include my drawing for u to see if i did it correctly.

    Example1.dwg

  7. #7
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    It's been a long day. How about you just post a DWG file? Life would be much simpler.

    To find out more about GUIDES consult your AutoCAD Help file re: SWEEP.
    I'm Reese. Sergeant Tech-Com, DN38416. Assigned to protect you. You've been targeted for termination.

  8. #8
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    Veggetossj,
    thanks for the trouble. Interestingly enough, the HELIX does not twist the profile.
    Nick

  9. #9
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    SWEEP

    Creates a solid or surface by sweeping an open or closed, planar or non-planar curve (profile) along an open or closed path. Open curves create surfaces and closed curves create solids or surfaces, depending on the specified mode.



    You can use the following objects and paths when creating a swept solid or surface:

    Objects for sweeping

    Objects that Can Be Swept
    Objects that Can Be Used as a Sweep Path

    2D and 3D splines
    2D and 3D splines

    2D polylines
    2D and 3D polylines

    2D solids
    Solid, surface and mesh edge subobjects
    3D solid face subobjects Helices
    Arcs
    Arcs

    Circles
    Circles

    Ellipses
    Ellipses

    Elliptical arcs
    Elliptical arcs

    Lines
    Lines

    Regions

    Solid, surface and mesh edge subobjects

    Trace


    NoteSelect face and edge subobjects by pressing Ctrl while you select them.
    To automatically delete the original geometry used to create the object, use the DELOBJ system variable. For associative surfaces, the DELOBJ system variable is ignored and the originating geometry is not deleted.

    List of Prompts

    The following prompts are displayed.

    Objects to Sweep
    Specifies an object to use as the sweep profile.

    Sweep Path
    Specifies the sweep path based on the object you select.

    Mode
    Controls whether the sweep action creates a solid or a surface. Surfaces are swept as either NURBS surfaces or procedural surfaces, depending on the SURFACEMODELINGMODE system variable.

    Alignment
    Specifies whether the profile is aligned to be normal to the tangent direction of the sweep path.

    NoteIf the profile is not perpendicular (normal) to the tangent of the start point of the path, then the profile automatically aligns. Enter No at the alignment prompt to prevent this.
    Base Point
    Specifies a base point for the objects to be swept.

    Scale
    Specifies a scale factor for a sweep operation. The scale factor is uniformly applied to the objects that are swept from the start to the end of the sweep path.

    Reference. Scales the selected objects based on the length you reference by picking points or entering values.
    Twist
    Sets a twist angle for the objects being swept. The twist angle specifies the amount of rotation along the entire length of the sweep path.


    Bank. Specifies whether the curve(s) being swept will naturally bank (rotate) along a 3D sweep path (3D polyline, spline, or helix).

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