Sweep Issue

[rymanvw]

Hi,

I am trying to make a tunnel using the sweep command and I am not sure how to go about doing it. I have some guide curves and a sweep path and profile but the path wont sweep Sldwrks says it has self intersecting geometry. I think I am doing my guide curves wrong. Thanks in advance.

[ReMark]

Not sure how it works in Solidworks but in plain AutoCAD I can pick either the outside or the inside path and sweep the profile of the tunnel and get the same finished result.

 

Are the paths, via the straight line on the right that connects them, one continuous object?

[shift1313]

put a fillet on your centerline path and try again using only the centerline. The self intersecting error is because of that sharp corner. It doesnt like that as a path.

[ReMark]

Why does one have to select the centerline instead of one of the two outside paths in Solidworks for the sweep command to work? Just curious.

[ReMark]

My tunnel sweep in AutoCAD. Middle image was swept using the outside path. Right image was swept using the inside path. Doesn't seem to be much difference.

 

[shift1313]

you can select the outside, or you can select a centerline and guides. The issue comes when you try to distort your sketch. The standard selection is to sweep a single path. For sweep to work with those guide curves i believe you would need to take the inner radius and do an offset curve out to your outter edge.

 

You could create your tunnel at the end of your curves and loft that with no issues.

 

If i get a second i will try to recreate that.

[shift1313]

Here is a screen shot of whats happening.

 

you can play around with the different normal settings and different guide curves. That screen shot is with the path and one guide curve. When i try to use both it fails. The closest i could get was using the loft command.

 

If you sweep just using the center path you can go back and fillet the edges but this may not be the result you are looking for.

[rymanvw]

the edges are not just a simple fillet. It is a more complex curve. I was getting the same results as shift when I tried using one guide. Shift did the loft work or no luck?

[ReMark]

A more complex curve? Could have fooled me. It's a tunnel. Why do the curves need to be more complex? Maybe I'm misunderstanding the use of the word "tunnel" here. Just what is it that you are constructing or fabricating?

[rymanvw]

I am doing a CFD of a wind tunnel. So I have to make a very accurate representation of the wind tunnel so that the calculations will be accurate.

[ReMark]

A wind tunnel. OK. What are the parameters for the horizontal curves you are depicting?

[rymanvw]

I would use autocad except I cant export it to solidworks or step or anything. But what you have there Remark is exactly what I want. I might just use Rhino but it isnt easy to dimension is rhino so I want to try to get it in solidworks first.

[rymanvw]

It looks a little like a parabola it is not extremely complex, but it is not as simple as a fillet.

[ReMark]

I guess that explains it. My civil background is more atuned to horizontal curves used in road layout. Can't help with the parabola so I'll just say good luck and hope you get it worked out.

[stevsmith]

autocad can export into solidworks!

[shift1313]

yes you can open a dwg right in SW no problems.

 

I did have luck with the loft but i only used two guides, you really need more than that. I would loft it with 4 guides(just a rectangle) then chamfer the edges after the loft. What are the specs at the corners? or maybe some rough numbers to work off?

[shift1313]

here is one i just did using loft and 4 guide curves then chamfer after.

[rymanvw]

I think if I do it in autocad it will give me the most accurate results. Thats what I am most concerned about. Thanks for all your help. I posted another one if you all wanna take a stab at it.

[shift1313]

I would have to disagree. I think SW will give you an accurate result, there are just more options that you have to play with to get exactly what you want. I think the loft will give you the most accurate because you are able to define all 4 corners(or 8 if you want the chamfer the corners pre-loft)

[jaims]

I'm not sure I fully understand the constraints on your design, but as ReMark suggested you can easily use a sweep defined by the outer sketches, rather than the centreline sketch.

 

You'll need to ensure that the construction lines you show aren't constrained as both VERTICAL and MIDPOINT, otherwise the swept profile won't be able to 'stretch' around the curves as the length of the rectangle changes (obviously the vertical edges stay the same length, but the horizontal lines will be all over the shop!

 

Use Pierce constraints where possible, perhaps adding points to the swept profile.

 

Have I missed something in the design?