Mobius Curve/Surface

[kimluckner]

Ok I'm stumped, how would you create a surface geometry of a mobius curve or portion thereof. Similar to taking a ribbon cable and putting a 90° twist in it. One end of a rectangle would be vertical and the opposite end would be horizontal?

Regards,
Kim

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[iturner]

Kim

There are quite a few ways to do this but here are two:-

1. Create a twist in a sheetmetal part.

or

2 Create a variable section sweep
-create a straight curve (or curved) as the trajectory
- create the sketch of a line passing through the trajectory (sketch at 45 degrees)
- the add a sketcher relation sdxx(angle dimension)=trajpar*90
e.g sd4=90*trajpar

The sketch will then twist around the trajectory


Ian Turner

CAD Manager

Cobham Mission Equipment

[TimMcLellan]

Kim,



I have attached an example. Sorry I could not get it to you yesterday but I
have not ran WF2 (did not have it installed until this morning) in a little
while and most of my data has been migrated to WF3 & WF4. I rebuilt a quick
example and have it attached.



To avoid self intersecting geometry it has two variable section sweeps. The
models I built for my company actually leveraged graph features but this is
a little more straight forward for most.



Please modify the twist (in relations) value to see the strip change.



Hope you enjoy the model,



Tim McLellan
Mobius Innovation and Development, Inc.

[ptc-680841]

Good ideas, Ian.

To add to the list, you could also use a Swept Blend. The Swept Blend will allow the ribbon to follow a 3D trajectory. The advantage of an advanced Blend is that the 90 degree rotation is controlled with an angle dimension. Easy to find, easy to change. With the Variable Section Sweep, the angle is controlled with a Section Relation (not a part Relation) similar to: sd3 = trajpar * 90

Not the easiest to find or understand for those that may work on the model down the road.

Just my $.02 (not adjusted for inflation).

Andy B.

[kimluckner]

Thanks to all,

Truly a talented and generous forum. I think my trajectory wants to be a conic. The part is actually a flexible circuit, so I have to be concerned about bend radius. Liek came closest to understanding my poorly written description. Easiest way to visualize the form I'm after is to take a piece of notebook paper lying in "landscape", take the right hand edge and move it so that edge is now parallel to the top edge, although above it, so I guess that's a 90 deg twist. Ideally I'd like to be able to both show the formed part in assembly and the flat shape in drawing. So I guess I'll look at a swept blend first and a variable section sweep 2nd.

Regards,
Kim