12-05-2007 20:08

Pavan Dave

Re: pic: mousetrap car

Was there a list of materials you could and couldn't use? Also where did you find someone to let you use their waterjet for your physics project? Congratz on your win.

12-05-2007 20:36

Jeremiah Johnson

Re: pic: mousetrap car

That's what I wanna know! I've got some Vex parts that could use some waterjetting. My guess, though, is that it was left over scrap?

12-05-2007 20:46

Aren_Hill

Re: pic: mousetrap car

one of our sponsors waterjets alot of parts for us and we had a batch going through so i snuck these in there it was scrap material that wouldn't have been used.

in physics we also did toothpick towers projects and you were limited to toothpicks and wood or white glue.
each group had to build 4 towers and our group average of 243lbs easily creamed everyone elses we used somepretty advanced constructions tecniques to construct them one tower included pegs holding the toothpicks together. that right we sanded down toothpicks drill a 1/32 hole and put them in. our strongest tower held 305lbs

12-05-2007 21:06

Nuttyman54

Re: pic: mousetrap car

yeah...this kind of success is what prompted the "never go against a robotics kid" mentality in my engineering and physics classes

12-05-2007 21:08

Re: pic: mousetrap car

I built a Popsicle stick bridge once... Sort of along those lines, it held about 600 pounds. It was about 4 inches wide, and like 20 inches long.

That also prompted the "never go against a robotics kid" attitude.

12-05-2007 21:36

Guy Davidson

Re: pic: mousetrap car

I wish we'd have more competative physics projects. We have to build a solar powered house (read hook up a solar cell to a few circuits with LEDs and resistors)...

12-05-2007 23:57

joshsmithers

Re: pic: mousetrap car

nice job on that, i'm sure you deserved the win. robotics kids always win. I, the only "robotics kid" in my physics class, have won two* of three competitions so far PLUS the final competition will be a Vex challenge. i hoping to take the cake.

*my egg-drop win is controversial**...
**of couse, ther was no un-gracious professionalism involved

13-05-2007 02:10

danshaffer

Re: pic: mousetrap car

physics got me into FIRST: I spent winter break in our lab building a rube goldberg. it was entirely over-engineered: in a class where most kids used cardboard and duct tape, we had welded aluminum and old robot batteries. it also weighed fifty pounds. after spending so much time in the lab, i figured i'd just stick around for FIRST season!

13-05-2007 13:18

geeknerd99

Re: pic: mousetrap car

Even for theatre, we've accidentally gotten the "don't mess with the robotics guys" mentality going. One of the people in our close-knit electronics group has been a techie for the last 2 years, and somehow, the entire group got sucked into the musical this year.

Collectively we ran sound (12 wireless mics!), lights, and running crew. More robotics-esque, we fixed 4 wireless bodypacks that had broken a few years ago, built signs that were no more than battery powered vision targets, wired up (safely) 10 strings of 100 christmas lights for a sign, and using hand tool skills developed over the last 3 build seasons, built 4 flats in the time it took the 3rd year techies to build one, and took down 6 platforms in the time it took them to take down one.

Yup, I'd say that robotics does teach you a thing or two that you can apply to other things in life.

13-05-2007 13:53

Qbranch

Re: pic: mousetrap car

Sweet mousetrap racer! Thing mustve flown... too bad you didnt have a cam.

Reminds me of when I built an autonomous vehicle for my 7th grade science fair from scratch... my first robot ever and it still won FIRST place in my school as well as the state regional for my division in engineering...

And two years before that in 5th grade the shower-temperature-monitoring device that told you if your shower was hot enough and warned you with a loud beeper if it was getting too hot... that one took FIRST at my school then third in the 6th grade engineering division (yeah a year above me)...

Anyhow, yeah, never go against robotics kids in engineering/physics/science classes.

-q

13-05-2007 14:07

tseres

Re: pic: mousetrap car

i remember when i built a mousetrap car way back in gr 8. it was fun....except my car stunk. interestingly enough, though, one of the best cars actually used magnets to hold the axles in place, therefore almost zero friction. mousetrap cars were fun, but robots are way better.

13-05-2007 15:01

chaoticprout

Re: pic: mousetrap car

Fellow 1138 members Jeff Kane and Evan Molenda made a sick Carbon Fiber / Balsa mousetrap car, that went for 30 seconds or so, and went like, across our cafeteria diagonally, it beat everyone by 4 or 5 times. Nicely done, i like the waterjetted part

13-05-2007 15:02

Scott Morgan

Re: pic: mousetrap car

I was hoping to see those cnc'd hard drive wheels you talked about in the other thread.
Of course, the water jetted chassis is even more awesome.

13-05-2007 15:32

sanddrag

Re: pic: mousetrap car

I had to make a rubber band powered car for a class project/contest my first quarter in college. I made the frame from soldered brass tubing. The car won in my class, and then took first place in the competition with the other classes. So, it beat about 50 other people I think. It went from starting position to twelve feet away in 1.1 seconds. Although, these days, I hear some are running in the high 0.9s

13-05-2007 16:08

DonRotolo

Re: pic: mousetrap car

OK, so all this gets me thinkingf: What makes a winning mousetrap car?

Well, if F=ma, and F is fixed, to maximize a we need a small m. Right? So I conclude the way to get the most is to have the smallest mass possible, all else being equal.

Yes, one must ensure the drive system is suitable - the string pulling the axle, the friction between the wheels and the ground, all that needs to be good, but there's a wide range of 'just fine' there. Also, you need to bring friction down to a negligible factor - those bearings are sick, but quite right.

If the CDs used as wheels could be swiss-cheesed, you should be able to get a lot better. Can you cheese the trap, too? (no pun intended).

Don

13-05-2007 20:18

Aren_Hill

Re: pic: mousetrap car

this mousetrap car was optimized for the grading scale(total distance/5m time)
by having the string pull on a cone that i actually managed to thread. this enabled the car to have the best acceleration in the class and the furthest distance due to its very low rolling resistance.

14-05-2007 12:04

Brandon Holley

Re: pic: mousetrap car

Don, while all of this is true...some contests dont just feature how fast the car is, but how far it goes too...which means you want o maximize distance (x or s).

15-05-2007 09:46

robostangs548

Re: pic: mousetrap car

That is sweet..... Your probably the only person that I know of that has ever used a water jetted frame on their MOUSETRAP CAR!

18-12-2007 21:07

RTTComanche17

Re: pic: mousetrap car

the "don't go against a robotics kid" came about in my physics class when we built trebuchets. they could weigh no more than 10 pounds - minus the counterweight - and had to throw a golf ball. Mine threw the golf ball 290 feet. Next closest was 150 feet (by a fellow robotics kid)

19-12-2007 03:14

ay2b

Re: pic: mousetrap car

A lot of that depends on the rules of the particular contest. The original poster's contest was distance/<time for first 5 meters>. This means that you want high accelleration. Other contests are just farthest distance. Others are fastest time for a set distance.

Way back when I was in HS, I built a mousetrap car where the score was the product of the mass and the distance traveled. Most of the entries were a few hundred grams and traveled a few meters. Mine was over 2 kilograms and traveled tens of meters. Only one other vehicle came close - it actually traveled slightly farther than mine, but was less than half the mass.

The main winning factor in my design was having a very high gear ratio. The wheels were 3-4 inches in diameter, and the axle was 1/4 inch. The mousetrap pulled a "ripcord" string which was wrapped around the axle. I made sure there was high friction between the string and axle, and low friction between the axle and the berring. Accelleration was very low, but the top speed was quite high.

The other design which did well was a hovercraft. It consisted of a container of dry ice which had a small hole in the bottom, and no other opening. The bottom of the vehicle was very smooth, and the floor was tile. This allowed the whole car to float on a cusion of CO2. The mousetrap was then attached and used to "push off" of a wall-like object at the starting line.

Mousetrap cars, balsa wood towers, popsicle stick bridges - these are all fun easy projects to work on that provide a great intro to engineering. Several years ago my FIRST team did one of these types of projects each week throughout the fall as a way to get the team to get to know each other and to learn various engineering priciples.

19-12-2007 03:21

Aren_Hill

Re: pic: mousetrap car

This car ended up having a score of 11.
22meters/2second 5m time.
most other scores were around 1 or less

19-12-2007 22:04

Kellen Hill

Re: pic: mousetrap car

Excuse me sir but I managed to get an 8 or so in that competition!

19-12-2007 22:36

T3_1565

Re: pic: mousetrap car

I remember doing this in grade 8 as well, My car used records as wheels! So my actually took the same amount of time for one rotation of a CD with almost three times the distance to travel. We didn't have any fancy do-dad's on it back then and ours went all the way down the hall and hit the gym door!!!

That was a highlight of my life pretty much and it was two years before the robot team started at my highschool (that I wasn't a part of at the time)

Congrats on the win!! I love the waterjet, we don't even have that for our bot lol!

20-12-2007 00:58

Blue_Mist

Re: pic: mousetrap car

Last year I attended my first Latin Convention (this is my sixth year taking Latin), and helped build a float-arm trebuchet that won the catapult contest by about twice as far as everyone else's catapults. It was this insane wooden and steel contraption about six feet tall with a three by three foot base. Since our leader graduated, I'm leading it this year! "Never go against robotics kids" for sure. I'm a happy nerd through and through.