Simple machine: screw

A screw is a machine that transforms rotational motion to linear motion. When you turn a wood screw, for instance, you are adding torque, or rotational force, but the screw translates this to a forward force, pulling the screw into the wood. An Archimedes screw (known since at least the third century BC and attributed to the Greek mathematician) uses this concept to lift water. Here are two LEGO versions of Archimedes screws to move little balls up a slope, both by Akiyuky. BTW, these were built as modules in Great Ball Contraption layouts. The GBC is a collaborative LEGO project where people build different modules that move balls from point A to point B. These modules all get strung together to make huge mechanism that are fascinating to watch.

Simple machine - wedge

Another machine that is so simple that it is easy to overlook is the wedge. The idea of a wedge is that due to the angled shape, as it is pushed forward, force is exerted outward (at right angles to the path of the wedge. Think, for instance, of a log splitter - you put the log splitter in the top of the log and hit downward with a sledgehammer. You are exerting force downward on top of the log splitter, but the result pushes the two halves of the log outward. Or even just an axe is a simple example of a wedge, with really the same idea. Axe by Demonhunter.



You killed Kenny! You b... by dm_meister

Simple machine: inclined plane

I got sidetracked from my series on simple machines. The next classical machine is perhaps the simplest of all, the humble inclined plane - a flat surface set at an angle connecting levels at different heights. I can see why some might not refer to a ramp as a 'machine,' but it fits the definition of changing the direction or magnitude of some force. When you push forward on a load sitting on the inclined plane, the slope of the surface translates part of that force into upward motion. Also, as anyone who's ever moved some heavy furniture into a U-Haul knows, it takes less force to move something along a ramp than it does to move it straight upward. You don't get something for nothing, though. To get this advantage you have to move the load over a longer distance, as the ultimate amount of work (force times distance) is the same. We see this in action in a moving truck by DadventureDan.

Pulley

Our next simple machine is a pulley (here by Evilnurn). A simple pulley changes the direction of a force transmitted by a cable as that cable moves around the circumference of the pulley. For instance, you could attach a rope to a rock and loop the rope over a pulley above you. If you pull down with a force of ten pounds, the result will be an upward force of ten pounds on that rock.


If you loop back and forth between two or more pulleys, you create a block and tackle (here by Louise Dade). This gives you a mechanical advantage. For instance, if there are two parallel stretches of rope, as in the model below, if you apply ten pounds of force in pulling the rope, twenty pounds of force will be exerted to lift the load. BTW, you never get something for nothing - you have to pull the rope twice as far to get double the force.

Lever

I was going to move on to the next simple machine, but Bobofrutx just posted this great example of a lever.

Wheel and axle

Next up in our look at simple machines is the wheel and axle. As with the lever, there is a relationship between the amount of force applied along the edge and the radial distance. Therefore a large wheel can be turned with relative ease, and yet be used to lift a large weight, as seen in this medieval crane by Stephle59.

Simple machine: lever

A simple machine is a mechanical device that changes the direction or magnitude of a force. Classical and Renaissance scientists defined six different ones. A lever (here by Linda Hamilton) is a rigid rod that pivots on a point called the fulcrum. In a class 1 lever, when a downward force is applied on one side of the fulcrum, an upward force results on the opposite side.



It also makes a difference how far the point of force application is from the fulcrum, as the actual term to be considered is torque, defined as the amount of force times the distance. The longer the lever, the greater torque can be produced, so that very large objects can be moved, as shown here by Ringleader. Archimedes supposedly said he could lift the earth if he were given a long enough beam and a place to set the fulcrum.

Gear up

A gear is a simple machine, where two or more wheels have teeth, or cogs, that fit together so that when one turns, the teeth fit together so that the other turns as well. In this way, rotational torque is transferred from one axle to another. These axles can be parallel to each other, or, as in this case by Legohaulic, at an angle. If the gears have different diameters, they will rotate at different speeds.

Book Review: Unofficial LEGO Technic Builder's Guide

Next up in my series of book reviews as last minute presents for the AFOL in your life. I'm posting this same book review across most of my blogs, but I'm adding some blog-specific content at the end of each posting.

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Unofficial LEGO Technic Builder's Guide by Paweł “Sariel” Kmieć, 2013, No Starch Press



On the one hand I might not be the right person to review this book. Even though I have fond memories of my best friend getting what must have been set 956 oh so many years ago, and at one point I got the Technic Jango Fett as part of a large eBay Star Wars LEGO lot, about the only thing I regularly do with Technic elements is put a small gear on a rod to make a mace for my castle minifigs. On the other hand, I'm pretty much the perfect market for this book, which is well situated for the builder who is fairly competent with LEGO building but has no real experience with Technic. That said, even the expert Technic builder would surely find this to be an extremely useful book. The author, Paweł “Sariel” Kmieć, is a well-known Technic builder. He's active in LUGPol and contributes to various Technic or NXT themed sites. You're quite likely to have seen some of his amazing MOCs on the Brothers Brick or other community sites, and you can find them all on his own site, Sariel.pl. Eric "Blakbird" Albrecht of Blakbird's Technicopedia is listed as a tech reviewer and advisor, and he may have helped with the illustrations, though that is not made clear.



This book is a beautiful intro to Technic building. Almost every page is full of full color illustrations - some photos, but mostly LDRAW - that clearly illustrate the topics under consideration. Without a lot of fluff intro, Paweł jumps straight into a discussion of the basics of Technic building. He starts out with a quick introduction to concepts of physics and mechanics that underlie the complex creations, goes through a comprehensive discussion of different Technic elements and how they work, and by the end of the book works you through intricate mechanisms, such as a ten-speed synchronized transmission, or a heavy-duty pendular portal axle. The complete Table of Contents can be seen here. The writing style is very clear, so you don't have to start out as an expert car mechanic to enjoy this book (believe me - I barely know how to check my oil). Along the way Paweł includes a ton of information. For instance, he goes through every type of gear and shows how they work, or in another chapter he gives a complete description of the advantages and disadvantages of every LEGO motor.



There are a couple of things that are not in this book. There is virtually nothing about Mindstorms or Mindstorms NXT, which are often grouped in with other Technic building. I actually don't think that's a failing, as to try and fit in a lot about programming and robotics would have necessarily led to a watering down of the content that is in this book. Also, No Starch has several other Mindstorms NXT books, which makes me think that this is part of a strategic plan to make a library of great reference works. The other thing that this book is not about is finished models. Yes, Paweł has a ton of photos of beautiful finished trucks, tanks, cranes and other models to inspire you, but he's not out to provide step-by-step instructions to make these. Instead he gives you step-by-step instructions to make the drive train, or steering mechanism, or other mechanics 'under the skin'. You can then build your own skin on top of this solid skeleton. Again, other No Starch offerings, such as these Technic Idea Books might be good to explore as a next step.



I would highly, highly, highly recommend this book (highly even) for anyone above the very introductory level builder. If you've never made a Technic model before but want to try, Paweł clearly teaches you from the ground up. If you're an expert Technic builder, you'll benefit from the comprehensive listings of different parts, and be able to adapt the complex mechanisms Paweł describes. Even if you've never had an interest in Technic, and those funny beams and half pins that occasionally show up in your System sets make their way into your 'useless parts bin' only to show up as an occasional greeble, you'll be inspired by this. Now I want to go dig into my own bin and pull out some gears and axles to play with!

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SciBricks-specific content This book goes through the basics of simple mechanics, describing things like different types of levers, gear ratios, pulleys, how speed and torque relate to power, etc.