(Very) Cheap and Easy Cart for a Science Fair Project...




About: Daddy-O...

My second-grade son is entering his Science Fair, and needs a cart for the soda bottle rocket he's making.

I pulled my Corel Draw skills together to come up with a (simple?) wheel and cart-body design to  build and use for the project.

Here are the drawings and project pieces I designed at TechShop in San Jose.

Including the free metal rod, the total cost was about fifteen cents!


Step 1: Check Out the File - Built for 1/4" MDF...

Here're the vectors and (not necessarily needed) text for the wheels, brackets, etc.  

I promise the wheels aren't perfect!  I recognized afterwards that I'd set some of the vent holes off-center - but this is not so critical for the project.

It happened that the scrap rod I found for the axles was .188" diameter.  I compensated for the laser kerf a bit and made the holes in the wheels and 'washers' about .188 diameter.  The "axle nuts" are around .186" diameter for the inside.

The drawing has lots of extra stuff - remove as needed.

Step 2: Put It All Together

I used CA (super) glue to put it together and save time.

The axles are about 5.5" long.

Step 3: Burn the 1/4" MDF

Attached is the file for cutting the pieces, in both .cdr and .eps.

I used the laser engraver to cut the pieces for the cart.   The 60-watt laser ran at 10% speed and 90% power for this successful cut.

Step 4: And Assemble...

I finished with 10 (separate!) fingers - another successful use of CA glue!

The test cart for the Soda Bottle Rocket is all set!  We'll use rubber bands to hold the soda bottle on the cart...



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    6 years ago on Introduction

    The 1 cup of vinegar and 2 tbsp of baking soda propelled the cart 131"!!!