Designing Trusses

Hi guys,

Been using rhino for a few years now and consider myself very adept at using the program, however for the past few weeks since I've been attempting to train myself the mechanics of grasshopper and it's functions and it's frustrated me to no end in terms of the complexity of it.

Basically all I'm trying to do is make a simple truss definition by extruding a closed curve of a truss along multiple curves. Normally, by doing this through rhino I would have to orient that closed curve perpendicularly through every individual curve and then extruding them. Since I have over a hundred curves to loft it would take me days to accomplish this task, whereas with grasshopper it would probably take minutes.

I really hate to sound ignorant, but all the tutorials I've read just confuse me even further to the point where I'm convinced I'm dyslexic or something. I've looked at the parametric truss video tutorials, and even downloaded some of the truss definitions around the internet, and it's like trying to translate japanese. I'm familiar with the terms such as series, pt, offset, etc. However, implementing those commands is what eludes me, in other words it's like going to combat training school, yet not having the experience to apply that in field and understand their meanings. I guess this explains why I failed computer science :/....

Anyways enough rambling, if anyone can show me just a simple definition for rhino file I have, and educate me as if I'm a 5 year old so that I can at least how to work this simple definition.

Here's my file, it's basically just the curves of the shell, and the enclosed truss curve i want to loft or extrude to create the structure.

Once again, I apologize for my lack of understanding and appreciate any help.

Attachments:

truss.3dm, 152 KB

Replies to This Discussion

Permalink Reply by Andres Gonzalez on April 28, 2011 at 4:42pm

http://web.mac.com/rhino3dtv/GH/GH_08_2_10_Curve_Demo_Line_3DTruss....

See if this video helps too.

Permalink Reply by Oowee Skee on April 28, 2011 at 5:12pm

Hi Andres,

Like I said in my post, I have a hard time understanding these kinds of tutorials, especially ones without audio, so all those steps in that one you linked has a pre-made definition with its own lines and curves, and since I already have my own developed lines, those extra commands which made those lines are unecessary? If at all possible is there a guide that simple shows how to extrude along a curve, with a perpendicular object?

Permalink Reply by Yoann Mescam (Systemiq) on April 28, 2011 at 5:36pm

1: profile curve to loft

2: rail curves

3: center of the profile

4: plane of profile

5: plane of profile aligned to center of profile

6: perpendicular frame at beginning of each rail

7: profile being moved and oriented on beginning of each rail

8: sweeping, each curve has its own rail, so inputs are grafted

This is probably not the expected result, but it can help.

Attachments:

Truss.ghx, 173 KB

Permalink Reply by Oowee Skee on April 28, 2011 at 5:56pm

Well,

I'm sorry Systemik, but you lost me at the first line where is says "profile curve" does that mean I have to "set one curve"? I tried doing that with just a single line curve and I got a hundred surfaces scattered all over the place. So I'm already stuck.

Anyways, I'm super short on time at the moment and I have to go, so it's up to you guys if you want to continue to help, I'm just so frustrated with this because I feel so helpless with no one physically to guide me through what all the technical terms means. I'll try and work on it later but right now I'm just too pissed off to continue for now. Thanks for trying guys.

Permalink Reply by Yoann Mescam (Systemiq) on April 28, 2011 at 6:43pm

1 is the closed curve you wanted to extrude (the truss section). It is in your rhino file (even if it is not closed).

This definition takes as input the section with 1, the rail curves with 2, then orient and moves the section curve to the beginning of each rail curves, and finally sweep it.

If you use the same rhino file you uploaded here, set one curve on 1, select the section, set multiple curves on 2, select all your curves; well it should work.

I am afraid I cant help you more than that.

Permalink Reply by Oowee Skee on April 28, 2011 at 9:45pm

Awesome...

Thanks for elaborating further for me, it helped a lot. I got another couple questions if you don't mind.

What specifically does Pframe and Sweep1 do, I have a vague idea for sweep1 one because I use that command a lot, but if you could elaborate on both that would be great. Also, how would you go about creating a boolean union and where to insert it on the definition. Thanks again....

Permalink Reply by Yoann Mescam (Systemiq) on April 29, 2011 at 12:33am

Perpframe is just a quick way to get a plane perpendicular to the rail curve, it gives the reference to move and orient the section.

The section curve will be perpendicular to the rail, but it probably needs to be rotated or the truss will vary depending on how the rails bend in space.

Sweep1 takes 1 or several profile curves and loft them while following 1 rail.

About the union, well I dont have any easy solution yet.

Permalink Reply by Oowee Skee on April 29, 2011 at 8:46am

Just noticed something strange, whenever I try to apply a circle as the curve to extrude, nothing happens. Is it because the definition parameters are set to specific curves?

Edit: figured it out, switched to circle center.

Now if there's a way to booolean union that would be great.

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