Sweep problem

[hydropwr]

I know this problem is all over this discussion board but I have not had any luck with some of the solutions.

I have a tunnel profile that I need to sweep around a path. This path is a 3D Polyline but it has arcs and slope associated with it. The sweep command has this automatic banking or twisting to it that just screws everything up. The profile needs to stay perpendicular to the path and the floor of this tunnel needs to remain flat.

I have attached the actual working drawing. It has the profile (which is a simple typical tunnel) and the path all situated if any of you can figure it out I  would greatly appreciate it!!

I'm working in AutoCAD 2012 if that really matters.

Thanks,

Dave

AutoCAD® 2013 Certified Professional

[nestly2]

Perhaps align a profile with each end of the tunnel, and LOFT using the 3Dpoly as a path.

[hydropwr]

Yes I did attempt this a while back with not luck. It still twisted the profile.

[nestly2]

If there's a LOFT profile on each end, the ends can not be "twisted" as shown in your drawing. I wouldn't think LOFT would "bank" out of plane through the middle section if the bottom of the profiles were aligned, but I didn't check to be certain.

Try this::

• Align one profile at each end of the tunnel
• copy the profile then make it into a block
• Use MEASURE or DIVIDE with the (B)lock option to array aligned profile blocks along  the 3DPoly path
• EXPLODE the blocks back into polylines, then LOFT the profiles in order
• In addition to lofting through however many profiles were placed on the path, the loft can further be constrain by using (P)ath option before ending the LOFT command.

This will "force" the tunnel floor to be "flat", (at least where it passes through each of the profiles that were arrayed on the path.

[hydropwr]

Great Idea!! Hadn't thought about that one!!

However, it did not work. It twisted even worse then the sweep. Kindof wild how this is working out.

I will attempt the Helix idea I have seen but not sure if it will work or not.

Thanks for the help!!

[nestly2]

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@hydropwr wrote:

...it did not work. It twisted even worse then the sweep...

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The profiles constrain the loft, so I don't know how that's possible.

Here's a video demo using your drawing --->  http://www.screencast.com/t/sm0vNQzBegjl

[JDMather]

ACISIN (I moved to origin).

[hydropwr]

Nestly

I love the video but have a question. What did you do to the profile block before the measure command. I did the exact same process but my profile does not align correctly to the 3dpoly.

Could you explain this a little bit please.

Thanks!

[hydropwr]

I just found a fatal flaw in this process Nestly. This creates a surface and not a solid. I need a solid to be able to subtract it from the model. This tunnel will act as the negative to be subtracted from my positive solid at a later time.

[JDMather]

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@hydropwr wrote:

I just found a fatal flaw in this process Nestly. This creates a surface and not a solid. I need a solid to be able to subtract it from the model. This tunnel will act as the negative to be subtracted from my positive solid at a later time.

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You can close the ends and use the Sculpt command (I think it is surfsculpt) to "stitch" surfaces into solids.

[nestly2 · Accepted solution]

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@hydropwr wrote:

Nestly

I love the video but have a question. What did you do to the profile block before the measure command. I did the exact same process but my profile does not align correctly to the 3dpoly.

Could you explain this a little bit please.

Thanks!

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1) The profile in your drawing is rotated.  Make sure it's not rotated inside the block.  ie set it at 0 or 90 degrees.

2) As I recall, the profile was not originally a closed polyline, and I believe it had some overlapping geometry as well.  I simply cleaned it up so it was just a 3 lines and an arc segment, then turned it into a closed polyline, which was then aligned with each end of the path and also used to create the block.  If it's not a closed polyline, it will be a surface, rather than a solid.

I actually don't think you need all those profiles, along the path. My experience is that LOFT doesn't "bank" the way "Sweep" does, so one profile at each end should be enough.

[hydropwr]

That was the key!! Thanks for the help and I now have the workflow I needed!! 

[sylvainleduc123]

Hi, something work for me, extrude sketch in surfacique for rail, cut surfacique, tickness for flat bottom and sweep your profil rail & surface. Good luck, take 2 days to figure out... 😕

[sylvainleduc123]

Ho! And when you sweep take only one by one sketch with simple géométrie 🙂

[sami.66m]

First you have to distribute the tunnel sections on the path. if there is the curved path then you need to put more sections for more smoothness , but its necessary that each section should be rotated in a way that it makes equal angles on both sides of path line. Then simply you have to use the LOFT command to join all sections.

you can check here Autocad file.

[dieters]

Just a tip . . . you might want to try out the EXTRUDE /Path command instead of SWEEP. In some cases that involve banking or rotating a profile along a path such as a helix (I'm thinking of a screw thread), the twist rate is going to be better.

Dieter