Lightweight Rubber Band Powered Car

One Friday my elder daughter came back from school and said that they have to prepare on weekend a project, any kind of rubber powered device from stuff that you can find at own home. Time was short, so we have started thinking and decided to create a rubber powered car. In my home's workshop we have found a lot of stuff. For this project we have used parts, that are listed in Supplies section + 3D printer.

Designing and modeling took about 11 hours ( a few hours on Friday evening and some on Saturday), the rest time we've been printing and assembling. For this model, steering system is not designed, because lack of time and RC details, but could be easily added.

The result of our project:

• experience in work with mechanisms, belts and gears

• we've got a lightweight rubber powered vehicle with range ≈ 90 meters and 170g weight.

• happy kids

• 1 x small piece of the aluminum tube 15 cm long and 8mm in diameter

• 4 x MR128 bearings

• 4 x 693ZZ bearings

• 5 x M2x8mm screw and nuts for them

• 22 x M3 Nuts

• 1 x M3x25mm screw

• 3 x M3x14mm screws

• 3 x M3x8mm screws

• 4 x M3x6mm screws

• 1 x GT2 Timing Pulley with 20 Teeth and bore 8mm

• 1 x GT2 timing belt loop with 100 teeth and 6 mm width

• 1 x 30cm of the M3 fully threaded rod

• 1 x pack of the mid sized rubber bands

• 3D printer

• Drill, screw driver, and other tools that could help in assembly.

There is no tricks in printing all attached models, all of them are could be easily printed with 0.4 nozzle. Tube for the rubber bands designed to be printed with no supports 0.2 layer height and 2 perimeters is enough.

Note: RubberHolder.STL requires to be printed twice, to get 2 PCS, the same is for wheels.

This step requires a few smaller stages. First one is to prepare already printed parts, so let's start.

• take the main gearbox part, insert 2 MR128 bearings

• insert 5xM2 nuts

• insert the 4xM3 nuts in their places

• insert 2xM128 and 2x693ZZ bearings to the second half of the gearbox Note: 693 bearings have to be pushed inside out

Next stage is to prepare our axels for gears and wheels.

• cut the aluminum tube to 3 part with 5 cm long each

• cut the the threaded M3 rod in the middle, to get 2 pieces with 15 cm long each

Assemble the axels for gears and GT2 pulleys.

• take a piece of the tube, insert it into the rubber holder hooks up to the end

• drill the hole through the tube and fix the hooks with tube by using the screw and nut

• take another one piece of tube and mount the GT2 pulley with 20 teeth in the middle of the tube

• screw 2 x M3x6mm into the 80T GT plastic wheel

• take the belt loop and assemble the gearbox

• install the larger bevel gear on the aluminum tube and do not lock it with screws, yet

• insert the M3 nut into the smaller bevel gear

• insert the M3 rod through the 693 and do not forget to screw the smaller bevel gear with 2 nuts, to get it locked on the axel

• adjust the position of the gears and make sure the gears are running smooth and with no jams, lock all gears with screws and nuts

In this step we have to connect previously assembled gearbox with the tube, inside of which we install our "rubber engine".

We need 5 M2 screws and a screw driver. Fix the tube with the screws on the gearbox.

That's it!

Take the last piece of the aluminum tube, rubber holder hooks, front cover and crank for he winding rubbers. Insert and lock the aluminum tube inside of the hooks part with the screw, like we did in the previous step. Thread the tube through the front plate, and lock it with the winding crank on the other side.

NOTE: Make sure that there is enough gap and winding crank could freely turned clockwise.

We've got the mid sized rubber bands, so we extended them by creating an "8" shaped loop, like on the attache image. With he help of the cocktail straw and fishing line, we've put the all 10 rubber loops on their place with no tears and in a short time.

Take the rear wheels and put the "tires" on them, which are 2 rubber band that inserted in the grooves on the wheel. Put the wheels on axels and lock them with nuts.

Put the front axel assembly to the front ent of the aluminum tube and we're ready to go.

Find the suitable open space wind the rubber motor, by using the from crank and get it run.

Thank you for reading.