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Mouse Trap Cars: CD/DVD Wheels

January 18, 2012

Learn more about using DVDs/CDs as wheels on your mousetrap racer. DVDs/CDs make great wheels because they can slice through the air with very little resistance.

Why do so many mousetrap cars use CD/DVD for wheels? Because CDs and DVDs are some of the best wheels you will ever find for building a long distance mousetrap powered vehicle. CD/DVD wheels can slice through the air with very little air resistance and they have very little rotational inertia. The only problem people have with using CDs/DVDs is how to attaching them to an axle set-up. The problem is that the CD/DVD has a large hole that some how needs to be tapered down in order to fit a smaller diameter axle. If you have a local hardware store nearby you can take your wheel with you to the store and test fit some of the rubber sink washer in order to find one that will work with your CD/DVD. Once you find a sink washer with a good fit in your CD/DVD you can then match-up the sink washer with the correct sized axle to complete your wheel and axle set-up. For most CDs/DVDs A 1/4-L beveled sink washer will work and this will tapper down to a 3/16-inch diameter axle. We also manufacture our own rubber washers designed for a perfect fit in any CD/DVD. Ours are made of a super soft rubber designed to also act as a shock absorber helping to decrease the energy loose and maximize performance.

bonus tip: test fit different sink washers at a hardware store in order to find the best fit that will also tapper the center hold down to a smaller axle.

Doc Fizzix CD/DVD Spacers

At Doc Fizzix we manufacture a special rubber insert that is designed to fit perfectly inside any CD/DVD so that it can be fit on a 3/16-inch axle. Spacers are made from a light weight flexible rubber that also acts as a cushion to smooth out the performance of a mousetrap vehicle. Our spacers also have an extra lip so that they can not pass through the CD/DVD but instead are held perfectly in place. Our spacers can also be used to center an axle between the frame of your vehicle in order to cut down on the "side-to-side" movement of an axle. This is a hard to find item and is really a "must have" part for making a mouse trap or rubber band powered racer. CD/DVD spacers comes in a pack of 20 CD/DVD spacers with a complete step-by-step instruction guide.

bonus tip: CD/DVD spacer can be used to tapper the large hole of a CD/DVD down to a smaller axle size.

How to set-up an axle system

Once you have selected your spacers there are some small tricks to using them with your CDs/DVDs, use the following steps as a guide for correctly setting up your axle system.

step #1: Press fit the CD/DVD spacer into your CD or DVD.

step #2: Carefully adjust the CD/DVD on the spacer so that the CD/DVD sits perpendicular to the floor and will also ride true without wobbling.

step #3: It is not always necessary to glue the spacers to the CD/DVD since they are designed to have a tight fit but some people like to use a little white glued to hold the CD/DVD and spacer place. Do not use super glue, super glue can eat into and destroy the material that the CD/DVD is made from.

step #4: Once the glues is dry, place the setup on to the 3/16-inch brass axle. Face the cone side towards the center of the axle so that the flat surface of the spacer faces out. Do NOT glue, you may need to adjust the spacer on the axle later.

step #5: Use a washer between the spacer and the frame to decrease any rubbing friction.

step #6: The spacers can be adjusted so as to center the axle and/or limit the side-to-side play of the axle set-up.

DVD Layers, The Winning Secret

DVD layers is one of those top secret tips that will definitely make your mousetrap car a winner. we manufacture a special DVD layer that is half the thickness of a normal CD/DVD and therefore it has only half the rotational inertia of a normal CD/DVD. Because our DVD layers have only half the rotational inertia of a normal CD, any mousetrap vehicle that use DVD layers for wheels instead of the regular CD/DVD will have a greater acceleration and a greater travel distance. By using DVD-layers travel distance will increase from 5-15 meters further for the same vehicle using CD wheels. Our special DVD layer package includes everything you need including wheels, axles, spacers, and thrust washers to insure that your mousetrap car is a winner. There is even a set-up guide filled with secret tips to make your project is a success.

bonus tip: DVD layers are half the thickness of normal CDs/DVDs and have half the rotational inertia. By using our DVD layers, your vehicle will travel 5-15 meters further than with regular CDs/DVDs as wheels.

Adding Traction to a CD/DVD Wheel

One way to increase the traction of a CD/DVD wheel when used on slick floor is to cut the center section of a rubber balloon and stretch it around the CD/DVD. This trick is only for normal CDs/DVDs and should not be used on a Doc Fizzix DVD-layer.

step #1: cut the center section of a rubber balloon as pictured.

step #2: stretch the cut section of the rubber balloon around the CD/DVD.

Decreasing the Rotational Inertia

This trick is not always necessary but for those who are wiling and a bit more daring this trick will make sure that your mousetrap vehicle is the best that it can be. Decreasing the rotational inertia of a CD/DVD will give your distance mousetrap racer that extra advantage over the rest of the competition. The best way to decrease the rotational inertia is to remove mass or give your wheel spokes. Mass can be removed with a drill or dremal tool by drilling and/or cutting on the outer rim of the wheel.

bonus tip: Here a pattern has been traced onto a clear CD/DVD using a template and then the excess mass was removed with a dermal tool. Download the same template here.

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