Mousetrap Vehicle C

[Teal]

So, just make the axles thicker?

[Flavorflav]

If torque is your problem , then yes. If you want to find out, disconnect the drive mechanism and push the vehicle across the floor - i.e., take the string off of the axle so it is basically a toy car. It should roll smoothly and coast for a good distance. If it does, your problem is probably torque. If it doesn't, it is friction.

[bwy]

So, just make the axles thicker?

The fact that you're asking that question means that you can make the axles thicker (ie, your car can make the distance with leftover string). If you can make the axles thicker, DO IT. (You can use tape, like someone suggested earlier. But pencil grips work well too, and they're not as tacky)
Also: I found out the name of the amazing things I'm using to hold my axles. Apparently they're called eye hook screws.
These are great because like Flavorflav said you need to reduce friction and they're rounded so there's barely any friction with the axles. I've never seen anyone use ball bearings, it seems like overkill to me

[Flavorflav]

Screw eyes, actually - I think you are confusing screw eyes with screw hooks. A screw eye would make a fair bushing, but because most of them are turned wire like the one in the picture they are not going to be as good as a real bushing.

[Teal]

Hm, it works much better, but now it can't reach the -4 line. Am I just stupid?

[Flavorflav]

That depends on what you did. If you widened the axle, you might be running out of string - the number of wraps stays the same, but each one requires more string now. If you have enough string, has mousetrap has completed its motion? If so, then your problem was friction and you compensated for it by increasing torque, but you are running out of power before you get to the -4 line and friction stops you from coasting to it.

[Teal]

We increased the amount of string, but now what happens is that it'll push the cup to the +3 line perfectly, hit the -4 line, and recoil, pretty much. Is there too much torque at this point? We lose about a whole meter.

[Danny Smith]

What is the best way to attatch axels to wheels so that they are perfectly straight. I know there are those black washers that fit perfectly over the hollow brass rods and the CD's snap onto them, but I am using a significantly different size axel. The methods I have tried to this point cause far too much wobble. Has anyone else found a solution to this problem?

[Flavorflav]

We increased the amount of string, but now what happens is that it'll push the cup to the +3 line perfectly, hit the -4 line, and recoil, pretty much. Is there too much torque at this point? We lose about a whole meter.

So, presumably its hitting the end of the string and you don't have a braking system. It just goes backwards? Most vehicles will roll backward and forward when they hit the end of the string. In any case, you should think about a brake.

[starpug]

We increased the amount of string, but now what happens is that it'll push the cup to the +3 line perfectly, hit the -4 line, and recoil, pretty much. Is there too much torque at this point? We lose about a whole meter.

So, presumably its hitting the end of the string and you don't have a braking system. It just goes backwards? Most vehicles will roll backward and forward when they hit the end of the string. In any case, you should think about a brake.

Wing nut brakes work quite well.