Advice on modelling V-shaped structural supports with tapered legs

[ryanesson]

Hi All, 

 

Hope this is in the right section, I am trying to create a working 3D model of an usual stage. I've got the .dwg files of the various 2D sections and elevations, but I am struggling with what workflow to take to model the pillars.

 

Please see attached screen shots. As you can see they start from a single base at the stage level, but then fork out and an angle to two separate places in the roof.

 

I've got the straight, single sections but cannot seem to work out what tool or modelling workflow to build the fork sections correctly in VW.

 

Thanks in advance for any tips or suggested workflows to try. Screenshots are from the various 2D .dwgs in my VW project.

 

 

Edited November 17, 2023 by Christiaan
Made title more descriptive

[VIRTUALENVIRONS]

Are the forked sections square beams that join together or elliptical is some fashion like the pedestal.  There are a number of ways to make this, but more clarity on exactly what you want would be helpful.

 

[Christiaan]

First method I would probably go for is to draw a circle* to the circumference of the large end of the fork and use the Model > Tapered Extrude... command to extrude it to the desired length and angle. Then manoeuvre them into place, select all, and Model > Add Solids

 

Though there are others much better at freeform modelling than me here and there may be much more sophisticated ways to achieve this.

 

*or square if it's square, or whatever shape it is

[VIRTUALENVIRONS]

For discussion purposes only.  Trying to figure out the shape.  Is this something like what you want.

 

 

[ryanesson]

Hi Both,

 

Thank you for replying. See responses below:

 

3 hours ago, VIRTUALENVIRONS said:

Are the forked sections square beams that join together or elliptical is some fashion like the pedestal.  There are a number of ways to make this, but more clarity on exactly what you want would be helpful.

 

The forked sections are round once they protrude from the pedestal. The circle sections tape slightly, so I figured a tapered extrude may be part of it. But I'm struggling to work out how to get the whole modelling done. If you look at the elevation screenshot there is kind of three parts to them there is the shape of the pedestal (which I easily copied from the .dwg), there is the fork section centrally, and then the tapered 'strut' which again is fairly easy to work out (tapered extrude).

 

3 hours ago, VIRTUALENVIRONS said:

For discussion purposes only.  Trying to figure out the shape.  Is this something like what you want.

 

 

Yes this is definitely the right direction, only as per above the forks turn circular (which is not obvious from the plan view screenshot).

 

 

3 hours ago, Christiaan said:

First method I would probably go for is to draw a circle* to the circumference of the large end of the fork and use the Model > Tapered Extrude... command to extrude it to the desired length and angle. Then manoeuvre them into place, select all, and Model > Add Solids

 

Though there are others much better at freeform modelling than me here and there may be much more sophisticated ways to achieve this.

 

*or square if it's square, or whatever shape it is

Thank you. This is definitely helpful for the arms of the fork, but its getting from the shape of the polygon of the pedestal, into the circular forks that I can't work out.

 

Ryan

[VIRTUALENVIRONS]

5 minutes ago, ryanesson said:

only as per above the forks turn circular

Are the forks circular from the top of the pedestal or do they morph from the fork shape I have shown to a circular shape. If so, how far up.

[jmcewen]

My approach would be to build it as 3 solids.  The first would be a tapered extrudeup to the break line you have drawn below the crotch.  Then I would extract the top face of that extrusion and birail sweep it across 2 polylines traced from the elevation view to complete the first branch.  Repeat with the same base ellipse and a new pair of rails traced from the other branch to complete the system

 

You could also do this with a loft.  Or you could do an extrude along path but tuning the taper will involve some trial and error.

[VIRTUALENVIRONS]

My apologies, I have had contractors in my house all day.  The information by the others is spot on. I thought I would run up the NURBS version (surprise surprise).  

 

Is this what you are thinking?  

 

If it works you can have it.

 

[jmcewen]

16 minutes ago, VIRTUALENVIRONS said:

My apologies, I have had contractors in my house all day.  The information by the others is spot on. I thought I would run up the NURBS version (surprise surprise).  

 

Is this what you are thinking?  

 

If it works you can have it.

 

In my mind, the 2 branches each taper from a full scale truncated ellipse, maintaining the same profile.  Forgive my sloppy screenshot markup-- I am posting from my phone.

 

1st branch is made by the red rails, the 2nd is made by the blue rails, and that thould form a neat miter line at the green line.  Of course the rails would be more neatly traced from the elevation to follow the true profile, and the green miter line would terminate at the break line just below the split.

[VIRTUALENVIRONS]

15 minutes ago, jmcewen said:

In my mind, the 2 branches each taper from a full scale truncated ellipse

Could be, I am just guessing.  I don't know what exactly it looks like. Downside of not being an Architect.  If I saw a picture of it, it would be a fairly straight forward model.  It could be probably built easier using just extrudes and sweep the rounds.

 

My two beams intersect at about the 3/4 mark, the fillet makes it look like they are separate.  

 

[Pat Stanford]

Best option for the forked arms that change profile would probably be a NURBS Loft in the No Rail mode so you could specify the "profile" at each location. As Virtualenvirons usually says, use "Matched Curves" meaning that each profile curve should have the same number of points so the "lines" between them will match exactly without the tool trying to interpret how they should fit together.

 

You could probably do it with a Multiple Extrude, but I think NURBS will give you more control. 

[Christiaan]

@ryanesson do you have any additional 2D drawings? Sections at different heights, elevations of different sides? Post everything you have.

[ryanesson]

Thank you everyone for your help so far on this.

On 11/14/2023 at 7:12 PM, VIRTUALENVIRONS said:

My apologies, I have had contractors in my house all day.  The information by the others is spot on. I thought I would run up the NURBS version (surprise surprise).  

 

Is this what you are thinking?  

 

If it works you can have it.

 

This is very close, but the circular forks sort of morph into the pedestal rather than stay round all the way until they meet. Thats what is making it a head scratcher.

 

Let me upload some actual photos....

[ryanesson]

Here is an image. Not the best, but you can see how it looks in the flesh so to speak...

 

 

[Christiaan]

ah yes, that's much clearer now. I think it would still be pretty straightforward to create using a combination of tapered extrudes and solid subtractions but I'm very curious to see what our NURBS specialist comes up with.

[VIRTUALENVIRONS]

Thank you, much easier to see.  Is this what you want?  There are only two curves involved in making this.  Just takes a few minutes.

 

 

Edited November 16, 2023 by VIRTUALENVIRONS

[VIRTUALENVIRONS]

Better rendering.  If this is correct, you can have the curves.

[Christiaan]

Nice work. I'm guessing that's perfect for what he needs, but could a solid subtraction be used to produce these flat bits?

[Christiaan]

Actually, it looks like you already have them in there.

[VIRTUALENVIRONS]

Hi Christian,

How are things?  

I made this rather quickly once I saw it.  It could be refined a little more.  The picture you posted shows the crutch is a little more smooth, so I would fillet it.   Also, I would add the indentations at the joints.

I think for @ryanesson purposes this would work.  There are only two matched curves @Pat Stanford involved in this. 

I may post short video later.

Paul

[VIRTUALENVIRONS]

Below is a short video showing the construction of the model with the added indents at the joints.  The construction curves file is also included.

Good luck

TWIN BEAMS .vwx

 

 

[Christiaan]

That's great, love it 👏

 

I'm all good thanks 👍