Full Version: Using Sweep on corners

I'm really sorry if this question has been ask and answered. Ive only found one thread that really goes into it. which is here: https://moi3d.com/forum/index.php?webtag=MOI&msg=2742.1

I am trying to get my sweeps to join on the corner.
I first tried sweeping it with the rails joined. but that gave me this issue:



So then I tried the method that is in the link above, but when I do, it corrupts the vertical sweep and does not trim the horizontal one:



What is the best way to get this done? My end goal is to use it to boolean into another mesh at the edge and then use blend or loft so I can get a fileted corner.


Thanks for any help.

Attachments:
Sweep.3dm

Image Attachments:
Joined.jpg  trim.jpg 

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Hi Billabong,

re:
> I first tried sweeping it with the rails joined. but that gave me this issue:

In one-rail sweep when there is a sharp corner in the rail it will attempt to do mitered corners by extending the sweep surfaces and trying to intersect them with each other. The intersection part gets much more difficult when the sweep rail is not a planar curve.

In that case it will leave the extensions so there is something to work with.


> So then I tried the method that is in the link above, but when I do, it corrupts
> the vertical sweep and does not trim the horizontal one:

This kind of messy result means there is some problem with the trim curves. Probably if you zoom in to where the curves look like they are crossing each other there will be some kind of anomaly there.

Your objects are at a rather small scale, it could help if you would scale them up by say 100x.

- Michael

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Thanks Michael. I was trying to model in real world scale, but in the end I guess it doesn't matter.

Ill check the curves for any issues and then Ill try and increase the scale.

Thank you
-B

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Scaling by 100% worked. Thank you Michael.

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Hi Billabong, also another possible technique is to do a sweep in 2 passes using 3 profile curves with the middle one slanted like this:







The pieces then will touch at their ends so they can just be joined with no extension and intersection needed.

The problem with that method is that the surface won't be an exact tube with a precise circular cross section at all points along the rail, the shape mutates a little bit as it travels along the rail and transitions from the circle profile to the slanted profile.

That's why sweep doesn't use that method currently but I would like to make it an option.

- Michael

Image Attachments:
billabong_sweep1.jpg  billabong_sweep2.jpg  billabong_sweep3.jpg 

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Thanks Michael. What if the actual rail had more than that one corner? Say 4 different corners. Can I use 4 different profiles or is 3 the limit?

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Hi Billabong, there isn't any limit on the number of sweep profiles. But for this other technique you only sweep one smooth piece of the rail at a time, between 2 profiles at either end of it.

That's to avoid extensions.

- Michael

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Understood. Thanks Michael.

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