Subject:
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Please critique my truss designs
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Newsgroups:
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lugnet.technic
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Date:
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Tue, 8 Mar 2005 16:47:36 GMT
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Viewed:
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3286 times
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Greetings, Technic builders!
I have been very impressed with the giant bridges and cranes that you folks can
build. Now I am working on a model that requires a truss. The model is minifig
scale, so I care about the look of the truss, as much as its strength. I don’t
want to secure three Technic beams together using triple pegs -- that’s way too
bulky for what I have in mind.
Still, I want to build something that won’t fall apart. So I thought that I
would ask you all for your comments before I buy a lot of parts that I do not
yet own.
I’m using a perfect Pythagorean 3-4-5 right triangle geometry for the diagonal
braces. Scaled up to use the 16L Technic
link parts for the diagonals, this gives a 9-12-15 triangle. I’ve tried two
designs, with the triangles in different orientations.
Here’s a wide truss:
Here’s a narrow one:
Half of the diagonal links are secured to Technic beams using friction pegs.
This is nothing new. But half of the diagonals are secured by attaching the
link onto the stud of a plate on one side. That’s pretty much all the firm
contact that this part receives. I stick a Technic half-peg into the other side
of the link and into another plate, but this contact is looser and may not be
adding much strength. I have one stud of empty space next to each diagonal
connection which cannot be filled with a square brick, because of the angle of
the link. However, I can place 1 x 1 round bricks in these spaces on the wide
truss, which might provide a bit more resistance to the diagonals popping out.
The round bricks also fill in the awkward-looking (to my eyes) holes.
On the narrow truss, even 1 x 1 round pieces don’t fit in next to the diagonals.
But 1 x 1 taps can still be squeezed in (and
I’ll use the taps to attach stuff to the sides of the beam):
I had just enough link parts to secure each beam of the trusses three times to
its neighbors. This was enough for me to build a minimal, rigid truss. The
designs seem to be reasonably stiff and strong, but I don’t have a lot of
experience with this.
I want to make a truss about a meter in length. I want to have a mass at each
end, like a dumbbell. Each mass will be about 300 grams. I want to be able to
place the model standing up, on one end, and I want to lay it down on its side.
I prefer the narrow truss to the wide one.
Does this seem practical? Do I need perpendicular bracing anywhere? (Again,
I’m going to care about its appearance as well as its strength.)
Thanks for your comments!
John Ladasky
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Message has 3 Replies:
 | | Re: Please critique my truss designs
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| In lugnet.technic, John Ladasky wrote: (2 URLs) (...) I'm going to leave the comments about the strength to more experienced builders (TJ? ROSCO?) but it certainly looks good. - David (19 years ago, 8-Mar-05, to lugnet.technic, FTX)
| | | Re: Please critique my truss designs
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| (...) Hi there! (...) Seems very practical to me. If the load is confined to the ends, your construction should easily handle it. However if you plan to suspend (lift/mount) it from any point on the truss, I would suggest adding a vertical brace at (...) (19 years ago, 8-Mar-05, to lugnet.technic, FTX)
| | | Re: Please critique my truss designs
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| (...) snip It looks good to me too. I've had good success with diagonals connected to the studs on the outsides of the beams. One example: (URL) I imagine that your design, with the diagonals "sandwiched" in their connection, might perform okay. (...) (19 years ago, 9-Mar-05, to lugnet.technic, FTX)
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