Building “half-stud”

A few parts, and combination of parts, that enables you to build “half-stud”.

 

Lego triangles and Pythagorean triples

Usually Lego Technic models are based on square patterns of holes which in turn are based on the Lego length unit “1 stud”.

The problem is when you want to attach a leaning liftarm to your (square) construction, how do you find the correct holes to attach it to? Usually the leaning liftarm “almost” fits.

I translated the issue into a mathematical problem. The base is of course a right triangle with the condition that all sides must be an integer. The phenomenon is called Pythagorean triples. (google it). I found the following triples especially interesting for the context of Lego.

3-4-5
6-8-10
5-12-13

Then I realized that Lego also “supports” “half stud” constructions which also enable the following combinations:

1,5-2-2,5
2,5-6-6,5

Note that the numbers above corresponds to the length between the first and last hole in a liftarm. To translate the length into the number of holes of the liftarms you have to add one (1). Below you can see the examples of the variations.

The building process

Designing a complex Lego Technic model requires a lot of planning, thinking and building. I left my "dark ages" during the summer of 2010. Since then I have recurrent periods where I build a few hours every week. However, within those I periods, I find myself completely stuck. In this article I will give you my best tricks for fluent building!

Using Linear Actuators for Articulated Steering

There has been a debate on how to build proper articulated steering with the use of double linear actuators (LA). The problem is that the steering ”speed” will vary over the steering ”cycle” when only using a single LA. As a result, when using double LA:s, there will tensions, that might be large enough to engage the built in clutches in the LA:s. However, depending on how you choose your ”geometry”, this problem can be reduced. This video shows one example of a geometry that will work fairly well, using the mini LA:s. It has been tested in vehicle up to 70 cm / 2 kg.

 

Bogie Axle with Leaf Spring Suspension