Scioly.org

how thick should the wood frame be

For the ETV
and is a rectangular frame better or like a dowel connecting the two axles

jay007 wrote:What's the best place to find pulleys for sprint/pulley launcher? Also, is friction a big issue here? Should we find ball bearing pulleys? Thanks!

We use clamp pulleys, that can be found on amazon.

http://www.amazon.com/Frey-Scientific-V ... mp+pulleys

http://www.amazon.com/Eisco-Labs-Pulley ... mp+pulleys

thomas_2002 wrote:

InfiniCuber wrote:

thomas_2002 wrote:Does the diagonal have to be 90 cm?

Which diagonal are you referring to? The string diagonal if you get rid of one of your pulleys so you only have 2?

like from the top of the launcher to the bottom but diagonally

The issue " does the .9 m apply to the launcher diagonally" has been answered in an FAQ at https://www.soinc.org/node/479

"2016-02-27 10:09 Does the "0.9 m in any dimension" limit go beyond width, depth and height to include all possible diagonal dimensions?
No, "0.9 m in any dimension" refers only to width, depth, and height."

Y NO ONE ANSWER MY QUESTIONS

Shanta wrote:For the ETV
and is a rectangular frame better or like a dowel connecting the two axles

I like to use 1/4x1/4 inch balsa wood. Its light and pretty sturdy. Just make sure you have bearings and do NOT attach them into the wood, but to the side or on top of it. I believe this is the lightest option, and I was able to get my car to weigh almost as little as the egg.

THANK YOU SO MUCH BAZINGA
where did you get the balsa though
home depot?

Bazinga+ wrote:

Shanta wrote:For the ETV
and is a rectangular frame better or like a dowel connecting the two axles

I like to use 1/4x1/4 inch balsa wood. Its light and pretty sturdy. Just make sure you have bearings and do NOT attach them into the wood, but to the side or on top of it. I believe this is the lightest option, and I was able to get my car to weigh almost as little as the egg.

i dont get what you mean by bearings to the side
I know I should have bearings, do you mean I put it on the axle right next to the wood?
thx

Shanta wrote:

Bazinga+ wrote:

Shanta wrote:For the ETV
and is a rectangular frame better or like a dowel connecting the two axles

I like to use 1/4x1/4 inch balsa wood. Its light and pretty sturdy. Just make sure you have bearings and do NOT attach them into the wood, but to the side or on top of it. I believe this is the lightest option, and I was able to get my car to weigh almost as little as the egg.

i dont get what you mean by bearings to the side
I know I should have bearings, do you mean I put it on the axle right next to the wood?
thx

What i mean is don't put the bearing right inside the balsa. Either have the side of the bearing resting on something hard which is connected to the side of the balsa, or have a bearing pillow block on top of the wood(search it up if you don't know what that is).

Thanks so much Eggo for pulley pointers.