Draw middle line through middle of irregular 2d

[Anonymous]

The attached photo will explain it the best.  The sketch shows an upside-down U shape with intentionally varying thickness.  I'm trying to draw a line exactly along the middle at every point.  Must be a straightforward way to do this (but, well, I'm new).

Bonus:  I wish there was such a thing as a three-point sweep -- one path and two guides!  My goal for the horseshoe involves an ellipse in the cross section at the top, slowly tapering to a spherical cross-section nearer the tips (unseen in this pic), while the lateral thickness also varies as shown.  (One path, two guides could do this.) Imagine a cone with a spherical cross-section nearer the point (trimmed and rounded off, fwiw), but squeezed to an elliptical cross-section nearer the wide end -- the whole thing then bent into half a U then mirrored into a full U.  (Phew!)

[g-andresen]

Hi,

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@Anonymous  schrieb:

Bonus:  I wish there was such a thing as a three-point sweep -- one path and two guides!  My goal for the horseshoe involves an ellipse in the cross section at the top, slowly tapering to a spherical cross-section nearer the tips (unseen in this pic), while the lateral thickness also varies as shown.  (One path, two guides could do this.) Imagine a cone with a spherical cross-section nearer the point (trimmed and rounded off, fwiw), but squeezed to an elliptical cross-section nearer the wide end -- the whole thing then bent into half a U then mirrored into a full U.  (Phew!)

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This sounds like a parlor game where an object or process is passed from person to person (whispering) and the last person has to say what it is about.

günther

[TheCADWhisperer]

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@Anonymous wrote:

The attached photo will explain it the best.  The sketch shows an upside-down U shape with intentionally varying thickness.  I'm trying to draw a line exactly along the middle at every point.  Must be a straightforward way to do this (but, well, I'm new).

Bonus:  I wish there was such a thing as a three-point sweep -- one path and two guides!  My goal for the horseshoe involves an ellipse in the cross section at the top, slowly tapering to a spherical cross-section nearer the tips (unseen in this pic), while the lateral thickness also varies as shown.  (One path, two guides could do this.) Imagine a cone with a spherical cross-section nearer the point (trimmed and rounded off, fwiw), but squeezed to an elliptical cross-section nearer the wide end -- the whole thing then bent into half a U then mirrored into a full U.  (Phew!)

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Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

Is you starting geometry (that which you absolutely know) fully defined? (This does not appear to be the case in the case in your image.) That is step #1.

What is your ultimate Design Intent, exactly what are you designing?

[Anonymous]

It's for pieces for a sculpture by my spouse. I'll need to clear out the project of other components before sharing a copy (b/c I can't show anyone the sculpture).  At the moment F360 non-paid is not letting me do a Save-As export.  But the file doesn't really reveal what I'm looking for anyway:  The intent is twofold: I'd like to know how, in a sketch, to draw a line that exactly bisects the tubular length of an irregular curving shape, because I believe I will be doing this a lot as I design the pieces.  The blue line seen along the middle shown above, I'd like that to be exactly in the middle at every point.

Then secondly, the practical intent for this particular component is to create a 3D U-body from a 2D U-shape drawn by the artist, that is "taller" at the top bend and "shorter" near the legs, along which the width also varies inconsistently.  So it is a difficult compound sweep that varies on all axes. 

Another way of saying it: The taper cross-section goes from the tall ellipse (6mm high) to the shorter circle (4mm high before it rounds off to a soft point at the ends), keeping in mind that the width of the sweep is also not consistent. If you look at the sketch above you can see that the lines spread apart a bit from the very top of the curve, then start to come a bit closer together again towards the finishing of the curve, then taper a bit more down the very long legs....

Attached is what I drew for you just now -- far too clumsy / wiggly with a mouse, but gives a rough idea.

[TheCADWhisperer]

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@Anonymous wrote:

At the moment F360 non-paid is not letting me do a Save-As export. 
But the file doesn't really reveal what I'm looking for anyway: 
The blue line seen…

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I did not write “Save As”.  Export exactly as I wrote and it will work with any license type.

But it will give me exactly the information that I need to demonstrate solution to your original question.  I need ONLY the geometry shown in your original image, I do not need any proprietary geometry.

Blue lines should keep you up at nights  - indicates that the foundation of your design is not robust and predictable.

[Anonymous]

The problem is I'm not allowed to show you the sculpture.  It's not for the public eye.  Think copyright and stuff.  But here, I mocked this desired component up in Photoshop just now.  It's exactly what I'm aiming for (top and side view of desired result): 

[g-andresen · Accepted solution]

Hi,

1 path + 3 profiles  >    loft + profiles + central path

günther

[Anonymous]

Loft!  And "central path"?  I'll give it a look - thank you -