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Chebeba · Guest

The challenge: I have a very slightly curved lofted surface with a
number of (about 20) holes cut for windows.

I also have a window part which fits the cut holes, but not exactly,
since the window edge is planar, but the cut holes have spline edges and
a very slight curvature to the faces, slightly different for each hole.

Now I don't care about a few tens of a millimeter mismatch between the
window and the wall cut, because there will be a 2-4mm wide weld there
anyway. But SWX cares, and makes it very difficult to mate the windows
to the holes.

I was looking for some kind of weak mate where I could basically say
place these three points on the window fram as close as possible to
these three points of the window hole cut (But only one point can be EXACT).

Seems to be no such thing. Any ideas how to accomplish this without a
lot of manual positioning (that won't update with modifications) would
be greatly appreciated!

/C

Zander · Guest

You can do it this way but it is tedious.... especially because you
must iterate each step for each window but it will properly position
your windows.

Create 3d sketch - convert edge of window openiing into sketch. This
will be a spline with 1 start/endpoint. Create 2 more points on the
spline. Close sketch. Use these 3 points to create a plane. Create a
2d sketch on this plane, sketch a circle and create relations between
the 3dsketch points and the cirle to center it over the opening. Then
you can mate your window to the centerpoint or edge of the sketched
circle. (note: there are many variations instead of sketching the
circle - find what you like the best)

Told you it was tedious and I would love to see another better way
posted.!

Sporkman · Guest

If you can place ONE point precisely on the spline edge of the holes,
and if that can be at the topmost or bottommost point, then I have a
solution for you . . . I think.

What you do is to create an axis which is vertical -- maybe using the
Front and Right planes if that is how your assembly is oriented.
Hopefully your window parts are symmetrical to their own Front/Top/Right
planes and one of those axes (for each window part) can be made
Coincident to the point that you place one the spline edge of each
hole. Then you can make that same axis also Parallel to the Assembly
axis that you created. Finally you can adjust the tilt of the windows
and their proximity to the part with holes in it so that they fairly
closely match the curvature of the outside of the part. You MIGHT be
able to do that by making one of the window planes Tangent to the
outside curvature.

'Sporky'

Mark Mossberg · Guest

Chebeba,

No offence, but if you find yourself stuck in this situation, you probably
aren't using optimal modeling methods. Your inserted (window) piece should
have it's base geometry extracted from the part it fits in. This is
especially important if the main part is a non-analytic (swept, lofted)
shape. You can either model the window into the main part as a seperate,
fully asociated, body, or in the context of an assembly.

Modeling two parts seperately and trying to work around the inconsistencies
is a kludge.

Regards

Mark

John Eric Voltin · Guest

Are the holes for the windows non-spline geometry except where they
intersect the lofted surface? If so, I assume you have already constrained
the windows in two directions and just need to establish the mate where the
window frame touches the highest point on the lofted surface. In such
cases, I would suggest creating a 3D sketch and placing a point freehand on
the edge of the hole approximately at the high spot of the lofted surface.
This point can then be mated to the back of the window frame.

--

- John

John Eric Voltin
Mechanical Engineer
Agile Technology
512-633-0394

John Eric Voltin · Guest

Mark,

You make an interesting observation, but it doesn't necessarily apply to all
situations. Chebeba describes the need to mate a standardized window
(apparently flat) to a slightly curved lofted surface. We obviously don't
have the complete story, but its easy to imagine that the models in question
accurately represent the parts as they will be manufactured (without undue
complexity and cost). Modeling the reality of a situation should not be
summarily classified as a "kludge". You can easily imagine methods to model
parts that mate very cleanly, but the resulting designs need to have good
manufacturability.

--

- John

John Eric Voltin
Mechanical Engineer
Agile Technology
512-633-0394

Todd_D · Joined: 09 Apr 2006 Posts: 2

you might try mating with planes Wink

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