Why do beams have 7:8 height to width ratio instead of 1:1?

[domleg]

Hello all,

This is my first post after a few years of lurking about - thanks to everyone for maintaining such an active community.

Recently I've been building a robot arm based on a vertical tower with 32L long worm gear with a nut. While struggling with lots of play between the grabber and the base I started wondering what is the reason for the 7:8 height to width ratio used in technic beams? Wouldn't 1:1 be so much neater from the all-direction, 3d building system perspective? I tried to google around, with little success. Has anyone got any ideas?

Thanks

domleg

[Rudivdk]

When making linkages, you do not want the part to rub against each other at the hinges. The flanges on the pins make sure all stays in grid, while the room between the beams make sure everything moves smooth. It is a trade-off I think, freedom of movement vs rigidity. But as seen on some builds here, rigidity can still be achieved with current setup.

[Aanchir]

Another way the narrower dimensions of Technic beams help is if you're working with both Technic and System. As discussed on pages 11 and 12 of this document, when attached to a Technic brick, a part the width of a full-size brick will collide with a brick or plate above, potentially putting stress on builds (why this happens is explained on page 2 — the hole in a Technic brick is raised slightly from where it'd be on a typical SNOT brick so it can accommodate the studs underneath). But the narrower dimensions of Technic beams prevent such collisions.

I imagine this was a deliberate consideration, since when the first Technic beams and half-beams came out, Technic was still primarily using bricks and not studless beams.