Although building a table saw out of LEGO is probably not the first thing that comes to mind when you look at those colorful bits of plastic, [Jamie] has been on a bit of a search for more applications of his LEGO-based air-powered motors. Naturally this led to the idea of doing something useful with it, like making a table saw you can actually use for real wood.

Starting off with a basic prototype using only regular LEGO pieces to get the mechanism figured out, [Jamie] then builds this up into said air-powered table saw featuring an actual metal blade. Suffice it to say that this isn’t something that you want your children to do with their LEGO while unsupervised.

The star of the show is of course the air-powered turbine that spins the blade. This is something that [Jamie] has been working on for a while, going through a number of prototypes to figure out a 3D printed geometry for the turbine blade that helps to convert as much of the high-pressure air into rotation.

Along the way it was also discovered that 3D printing saw blades is pretty hard, probably due to the lack of a sharp edge. This is definitely an area where it’s hard to beat a real table saw blade, with the added caveat that anything that’s good at cutting up boards of wood and sausages will just as happy slice through careless primate fingers.

In terms of safety features, the air supply is cut automatically with a sort of dead-man switch that requires you to keep one hand on it while using the final table saw design. There also an auto-feeding system added that tries to guide the board into the saw, but this turned out to be finicky. Suffice it to say that an air compressor and a handful of non-LEGO-approved components created a pretty convincing table saw.

Before LEGO train sets moved to battery-powered locomotives with plastic rails, all of them worked pretty much like any other train set of the era. This meant metal rails that the locomotive’s wheels would use to pick up power from and a central controller that would inject said power and also regulate the train’s speed and direction. The LEGO 2868b Electric Train Speed Regulator is one such example, and [Nonsense Wars] recently had one under the knife to repair it.

The single PCB inside is quite straightforward, with the 9-12 VAC supply input from an external power adapter, and a variable voltage regulator that sees its target voltage switched by a bank of resistors.

It are these resistors that the big yellow control switches between when you operate it, changing the output voltage and also output polarity you cross the midway point. Effectively this means that there is just one non-passive component on the PCB, in the form of the TO-220 package strapped to the big heatsink.

In this particular unit it was found to be a Fairchild KA317, which is for all intents and purposes here the same as an LM317T. One quick swap later and this controller was back in business like it was 1995.

Compared to the engineering crammed into a modern “smart brick”, things really have come quite a ways in the world of LEGO.