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Control project(use) direction or alternate technique?

laird_broadfieldlaird_broadfield Member Posts: 42 ✭✭
edited July 2015 in Community Support
I'm struggling to control the direction of the project(use) function -- and it's more confusing because I'd swear that 8 times out of 10 it works one way, and 2 times out of 10 it works the other way, and I can never figure out how to reproduce the 2of10 way.


This is my demo of the issue.  (https://cad.onshape.com/documents/27349a7d22794a6a993806f6).  
Across the middle is the Top plane, with a circle sketched on it.  There's a line-angle plane at 45 degrees.  I've created a sketch on the angled plane, and projected the circle from the first sketch.  What's happened is what happens nearly all the time; it's been projected along the normal from the sketch plane.

What I often want (and I think happens occasionally, but I can't figure out how) is to project it normal to the projected entity's plane.  That is, in this case, the projected oval would be directly "above" the origin entity.

How can I make this happen?  Is it a specific order of operations with project(use), or is there some other technique I should be using?

Thanks.

Best Answer

Answers

  • Narayan_KNarayan_K Member Posts: 379 ✭✭✭
    Sketch entities are always normal to sketch plane.If you project a circle,it will be normal to sketch plane.To get a projected sketch normal to projected entity, your sketch plane should be parallel to projected entity's plane.

    In your case if you want a circle in the angled plane which is related to circle drawn in top plane then you have to revolve the circle drawn in top plane up to 45 deg. then you can project the entity.


  • jakeramsleyjakeramsley Member, Moderator, Onshape Employees, Developers Posts: 657
    I would probably extrude as a surface up to that sketch plane.  That should give you an edge that you can project that should give you what you want.
    Jake Ramsley

    Director of Quality Engineering & Release Manager              onshape.com
  • laird_broadfieldlaird_broadfield Member Posts: 42 ✭✭
    Narayan_K said:
    Sketch entities are always normal to sketch plane.If you project a circle,it will be normal to sketch plane.To get a projected sketch normal to projected entity, your sketch plane should be parallel to projected entity's plane.

    In your case if you want a circle in the angled plane which is related to circle drawn in top plane then you have to revolve the circle drawn in top plane up to 45 deg. then you can project the entity.


    Ah.  No, I want the oval, not the circle -- but I want it as-seen-from-above.  IOW, if I drew a normal line from the original circle's center point, it would pass through the center-point of the projected shape.
  • laird_broadfieldlaird_broadfield Member Posts: 42 ✭✭

    I would probably extrude as a surface up to that sketch plane.  That should give you an edge that you can project that should give you what you want.
    Okay, did that, got an edge, projected the edge into a new sketch:

    That's the circle I want -- how do I get rid of the extrusion without leaving my new circle dangling?

  • jakeramsleyjakeramsley Member, Moderator, Onshape Employees, Developers Posts: 657

    I would probably extrude as a surface up to that sketch plane.  That should give you an edge that you can project that should give you what you want.
    Okay, did that, got an edge, projected the edge into a new sketch:

    That's the circle I want -- how do I get rid of the extrusion without leaving my new circle dangling?

    Hide it or use a delete part.
    Jake Ramsley

    Director of Quality Engineering & Release Manager              onshape.com
  • laird_broadfieldlaird_broadfield Member Posts: 42 ✭✭
    edited July 2015
    That's the circle I want -- how do I get rid of the extrusion without leaving my new circle dangling?

    And just to anticipate: I know I can delete the extrusion and remove the projection constraint... but that uncouples new-oval from first-circle, so that edits to first-circle are no longer carried through.  At that point, I might as well get my lead pointer and pounce bag out.  :-)
  • laird_broadfieldlaird_broadfield Member Posts: 42 ✭✭
    jakeramsley said:

    Hide it or use a delete part.

    Okay, I found "Hide" (I haven't used surfaces enough to realize they are independently hide-able.)  Will the hidden surface have any effect on the final part?

    Sorry: "use a delete part" -- could you expand on that?
  • billy2billy2 Member, OS Professional, Mentor, Developers, User Group Leader Posts: 2,014 PRO
    edited July 2015
    Projection seem to be working for me.


    I'm sketching on the 'right' plane and 'use' the bottom of the cylinder which is being projected onto the 'Right' plane:


    The project is normal to a sketch plane, not sure it should be otherwise. If you want to change this projection, change your sketch plane direction:



    Now, the extrude direction is an improvement needed:

  • laird_broadfieldlaird_broadfield Member Posts: 42 ✭✭

    We have a feature called delete part.  This will parametrically delete the part at that instance in the feature tree.  This works because when the sketch is computed, the surface/part exists and then it is removed after that.

    1. Select [...]
    Got it; thanks.  Hadn't yet had occasion to use that; now it makes sense.
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