BrickEngineer: LEGO Design

LEGO Engineering for LEGO NXT and Robot Enthusiasts

LEGO Triangles

LEGOs are designed to go together to form rectangles.  Here I present some possibilities for equilateral triangles, which can be extended to form hexagons.  Some of the more recent triangle designs, which I present below are being used in a current design for a tri-wheel drive system for a Mindstorms rover I am currently constructing.

These first triangular designs are equilateral triangles (same side lengths), and can be put together to form hexagons as well.  These are extremely sturdy constructs and may find use in triangular or hexagonal bases.

Below is the smallest LEGO equilateral triangle.  The parts used to construct it are shown to the right.  It often takes a bit of pressure to snap this together since it is a tight fit, so take care when doing so.

One can make equilateral triangles of any size this way.

Big Triangle

If the connectors are a bit cluncky,
one can use the thin technic liftarms with the small axles to secure the triangle.

Alternate Triangle Design

Here is a rotating image of the result so you can get a good look.

Alternate Triangle Design

The two following designs are slightly alternate forms.
One uses beams of length 11, but is offset slightly so that there are empty peg holes at the corners of the equilateral triangle.

Alternate Triangle Design

The following design uses beams of length 9, and lacks holes at the triangle corners.

Alternate Triangle Design

The following triangle is composed of beams of length 11, and has a a 3-blade rotor in the center to act as an axle.  The parts list and instructions can be found here.

Equilateral Triangle with Axle

An animated version illustrates how the braces hold the central rotor in place.

Equilateral Triangle with Axle

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Category: Constructs, Geometry
  • Alex Dimitrov says:

    Hi, Kevin

    What CAD system do you use do design and render your constructs?


    October 16, 2007 at 10:23 am
  • admin says:

    Hi Alex,

    I use the LDraw package with MLCAD to record the designs.
    I then use L3PAO (part of LDraw) to generate the POV files for POV-Ray for Windows 3.5

    I see that you do neuroscience research… me too!!!

    Please let me know if you have other questions.

    October 16, 2007 at 11:34 pm
  • Rich says:

    In an effort to keep you awake at night pondering this, how would convert your triangle concept into a model of the Gateway Arch in St. Louis?

    January 14, 2008 at 12:09 am
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  • adam says:

    Great deisgn on paper – when I go to build the 11 lenght liftarm triangle using the 1/2 liftarms (1×3) and the (1×2) they are an extremely tigh fit against each other. So much force is necessary to keep the triangle aligned, that the 1×11 liftarms are actually bending in the middle – to much stress!

    My chance, did you get an opportunity to build this model after desiging it on papaer to see the fit of each piece against the next peice.

    The stress placed on the each piece after construciton will cause premature wear.

    April 24, 2011 at 5:35 pm
  • admin says:

    I not only tried them, but I have used them in several robotic designs.
    The fit is indeed tight, but I have not found it to be as tight as you describe.

    I would make sure that all liftarms in your design are indeed 1 x 11.
    I cannot imagine how the liftarms could possibly be bending if they were the same length.
    If one was longer or shorter than the others, then what you describe should indeed happen.

    The critical part of the design is not the side length of the triangle, but the 60 degree angles at the three intersections.
    Since these angles are the same for any equilateral triangle, the joint will work equally well with any straight liftarms as long as they are the same length.

    I hope that this helps!

    April 24, 2011 at 5:49 pm
  • Vikram says:

    Amazing post, truly!

    May 14, 2011 at 4:05 am
  • mfeldt says:

    If the connectors are too tight and the triangle is large: The 3M liftarms can be replaced by 5M liftarms that go 2 holes further away from the corner. Or by 7M levers or bars that go 4 holes further out. Or by 9M levers that go… you get the idea.

    May 20, 2015 at 7:38 am

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