Robotics, Making a Gizmo with Lego Gears


How many different gears are there? what they do? and how do they connect together
spur gears 8, 20 & 24 tooth Spur Gears: These are the most common gears when you want to transfer power from one location to another.
crown Crown gears normally used when axles are meeting at a right angles. They have pointy edges like a crown.
bevel gear Bevel Gears: normally used when axles are meeting at right angles. They are smaller than crown gears and can only be paired up together. You can't put a bevel gear with a crown or a spur.
double beveled gears

Double Beveled Gears: these come in three sizes and can be coupled with the spur gears. The cool thing about these nifty gears is that you can put them side by side or at an angle. You can gear up or gear down the speed of the rotation by changing the size of the gear.

Caution:two gears of the same size will not mesh with each other.

worm gear Worm Gears: This gear is used when you want a lot of power and is usually the first gear. If you want to make a mechanical gadget this would be the gear that you attach to the turning mechanism ( servo-motor or the turning handle)
knob gear Knob gear: The knob gear only has four teeth. It is useful when you want to make a 90 degree connection and you are worried about the gears slipping. It will not give you a lot of speed but it will give you torque (power)

Images and text are paraphrased from James Trobaugh book The "Winning Design!: LEGO MINDSTORMS NXT" Design Patterns for Fun and Competition. - 14 December 2010. Published by Apress .

Now we get to create our gear building blocks that will power our gadgets

collect pieces

Find the pieces above and make a dynamic structure to create a swinging motion. What is this?

dynamic structure instructions
flexible Insert two smooth pegs into a 9 hole beam, then insert two smooth pegs into a 11 hole beam, connect the 9 hole beam to the two others and you have a folding structure that you can attach to your rotating gears.
worm1worm 2worm 3 Try to make these three gear boxes using the worm gear.
gear ratio

Step 1: You need a 8-12 hole lego beam, two axles, one 24 tooth spur gear and one 8 spur gear. Turn the small gear.

How many times does the gear have to spin for the large gear to turn once?

When you turn the small gear clockwise which way does the big gear turn?

gear ratio 2

Add another 8-12 hole lego beam, two axles, one 24 tooth spur gear and one 8 spur gear. Turn the small gear. Fit it together.

What is happening?

gear direction Can we use the "L" shaped beam? When would we use it?

Could we connect the L beam instead of the straight beam as in the image above what will happen?
verical gears

What about lining up gears? What if I want to build three interlocking gears?

Can I connect this building block to the horizontal building blocks?

The following Photographs and information are from the "Unofficial LEGO MINDSTORMS NXT 2.0 Inventor's Guide David J. Perdue - 1 January 2011 No Starch Press - Publisher

Learning about Gears:

Making Art:

Other Gizmos:

Use all three components to make a mechanical gadget. Can I use each of the gear boxes to make a box ? Can the lego men spin on the axles? What else can I attach to these blocks to create a innovative gadget?