Engineering Fair project

[hongher2005]

hmmm... I can think of a basic way to make this thing, but could you tell me how to assemble a flywheel?

also, one more.. could you tell me please which materials for parts would work best? like wheels.. large, but where could i find them? and what would be a good thing to use for my chassis? if you could help me with that, with the info i have, i could make a pretty good model for my car. thx!

[Turtle]

Originally Posted by hongher2005

hmm ill work on it..

so the flywheel.. is there any specific way it works? or do i just add it to the car instead of wheels.. or is the flywheel inside the wheels?

OK I searched the house high and low for a wind-up toy. I found one, but it does not have a flywheel much to my chagrin. Chalk that up to me bein' an old fogey and when I was a kid taking apart wind-up toys, they all had flywheels.

So, here's a photo montage of the drive unit. Rather than a flywheel to even out the spring tension release, it uses an escapement like a clock. Very clever.

Keep in mind this is supposed to be a learning process for you. The mistakes you are about to make actually working with the materials is where the real learning gets done.

[hongher2005]

i see.. hmm alright. but the materials.. can i just buy them? like ask for a wheel and they give em to me? and also, the drive thingy.. i have no idea how to use it

[Turtle]

Originally Posted by hongher2005

i see.. hmm alright. but the materials.. can i just buy them? like ask for a wheel and they give em to me?

The last time I went to a hobby shop to buy gears, they looked at me like I was mad, and kept looking until they were sure I had left. I have in the past -long past- seen catalogs selling bags of parts but I don't know of any in specific nowadays.

Go to Goodwill or your thrift store of choice and get some old mechanical toys with gears and then cannibalize them. Keep in mind scale, as you have to carry the 1 pound load as well as the vehicle weight. Gears as small and light as in the toy I gutted seem too delicate to me.

You could make your own gears by either attaching pins to the edge of a disk or cutting notches in the edge of a disk. Do you have much experience with tools? Is everyone doing their own vehicle? What are the other students doing? Do you have a wind-up toy to take apart? That's all I got.

PS I just reread the thread and realized this is a 7th grade project. I'll try & keep it simpler.

[Turtle]

OK Building on Craig's spool arrangement. I used an appropriately sized rubber band and found I could wind it tight on the spool ~4 times. To compensate for no gearing, I suggest very big wheels.

Here is a rough design that uses only corrugated paperboard, pencils, and the spool. The rubber band should detach from the spool when it unwinds all the way I think, so you take advantage of any coasting. Hope this is more helpful.

[hongher2005]

hmmm.. looks similar to the design i had.. alright.. ill try that, but I dont have any gears or anything to take apart.. well, BACK TO THE DRAWING BOARD!

[freeztar]

Originally Posted by hongher2005

I dont have any gears or anything to take apart.. well, BACK TO THE DRAWING BOARD!

Plastic Gears - bag of 20, assorted sizes | Edmund Scientific

That site has a gear "toolbox". But it might be even better to build your own.

What lightwight material might work as a gear? How would you construct it to work with the rubber band?

[hongher2005]

thx a lot for ur help! I think im just guna make my car simple because no one at my school has any idea how to make theirs.. haha. so large wheels, spool, thread, wood chassis, and something to slow the movement of my car.. sound good?

[freeztar]

Originally Posted by hongher2005

and something to slow the movement of my car.. sound good?

Everything you mentioned sounds great, except for the part I quoted above.

You don't want to slow the movement of your car. You want it to go far.

[hongher2005]

Originally Posted by freeztar

Everything you mentioned sounds great, except for the part I quoted above.

You don't want to slow the movement of your car. You want it to go far.

ah, but i just want it to slow down but have as just as much strength.. but the thing is.. i was wanting to know if it could happen without making it lose power