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ptc-5936191-Visitor
1-Visitor
July 7, 2006
Question

Drafting a cylinder end

  • July 7, 2006
  • 1 reply
  • 1528 views
Pro Modelers,
When drafting the end of a cylinder, I usually choose the edge as my draft hinge. Pro then picks the end of the edge as the draft point and invariably this is not the point I want, I suppose this is because Pro looks at a cylinder as two semicircles extruded. Short of putting in a tangential plane every time, is there any way to force the draft point to the middle of the edge?

Your help is always appreciated,

Richard A. Black
tel: 269 781-0539
-
http://www.automotive.eaton.com


    1 reply

    B
    BrentDrysdale12-Amethyst
    12-Amethyst
    July 8, 2006
    Hi Richard,
    The draft method you describe will not give you a flat draft surface so
    unless this is your intention to have a curved surface you want to use
    neutral plane instead. I have made three pictures part way through the
    draft feature that show what I mean. Hopefully they will come through
    the size limit.

    draft_use_edge_15.jpg
    Shows the method I think you are describing. The top semi circle of the
    cylinder stays unchanged and a curved draft surface drafts away from the
    original face using the central datum as the pivot direction (you could
    also use something like a default coordinate system for this).
    Sometimes it is important for an edge to remain true in which case then
    use this method. The draft in the picture does not show up so clearly
    but you can see that it follows the top semi circle and gets darker as
    it gets to the far side indicating that the surface has gone behind itself.

    draft_neut_plane_ctr_15.jpg
    Drafts the same end cylinder surface but uses the central plane (though
    the ends of the semicircles) as the neutral plane and draft direction.
    This gives a flat drafted surface. Probably the most used method as it
    allows non connected surfaces to be drafted using the same neutral plane

    draft_neut_plane_top_edge_15.jpg
    Drafts the same end cylinder surface but uses a top datum plane made
    tangent to the cylinder as the neutral plane and draft direction. This
    gives a flat drafted surface.

    Depending on your construction both of the last two methods may require
    a constructed plane if there is not one already available to use.

    Hope this helps.

    Regards, Brent Drysdale

    Mechanical Designer

    Tait Electronics Ltd (www.taitworld.com)

    New Zealand

    Ph. +64 3 358 1093



    - wrote:
    >
    > Pro Modelers,
    > When drafting the end of a cylinder, I usually choose the edge as my
    > draft hinge. Pro then picks the end of the edge as the draft point and
    > invariably this is not the point I want, I suppose this is because Pro
    > looks at a cylinder as two semicircles extruded. Short of putting in a
    > tangential plane every time, is there any way to force the draft point
    > to the middle of the edge?
    >
    > Your help is always appreciated,
    >
    > Richard A. Black
    > tel: 269 781-0539
    > -
    > http://www.automotive.eaton.com
    >
    >
    >
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